Sustainable Energy - without the hot air

Version 3 of the 2050 Pathways Calculator

2012-01-08T03:15:00.000-08:00

In December 2011, DECC published the Carbon Plan and version 3 of the 2050 Pathways Calculator.

As before, this open-source engineering-based tool is intended to support grown-up conversations about our possible energy futures. The user can choose any combination of demand-side and supply-side actions over the period to 2050, and the calculator computes and displays various consequences - energy flows, areas of land use, greenhouse gas emissions, and some security-of-supply indicators. The significant new feature in version 3 is the inclusion of costs, for the first time. Version 3 of the calculator also includes an air-quality calculator, which, like the costs calculator, is under development. Expert feedback is welcome.
Future costs are uncertain, and there are a range of views of the future costs of key technologies such as building insulation, low-carbon vehicles, nuclear power, wind power, carbon capture and storage, heat pumps, and energy storage technologies, and key fuels such as oil, gas, and energy crops. These ranges are reflected in the calculator's cost sensitivity visualizer by allowing the user to change the costs from the default values to higher or lower values, consistent with the ranges that DECC has found in the expert literature. The user can also visualize the consequences of cost uncertainty by selecting the Uncertain choice for any of the costed items. The calculator then shows the range of possible costs for the user's chosen pathway.
All the cost ranges, and the original sources, are explicitly detailed in an open wiki, to which experts are encouraged to contribute updated data. You can click through to the relevant bit of the wiki from any row of the cost-sensitivity page of the calculator. The wiki contains superb interactive visualizations of the cost ranges from the literature. Here's the Offshore Wind Costs Data visualization, for example.

In the 2050 Calculator, you can compare the costs of your chosen pathway with other pathways, for example a handful that DECC has published, or those of experts. In the "Costs compared" view, you can compare all the pathways' costs simultaneously. In the "Cost sensitivity" view, you can compare your pathway in detail with one other comparator, which you can choose. In the web version of the calculator, costs are expressed in pounds per person per year. These are whole-energy-system costs, not people's home energy bills. For example, the costs of vehicles, building retrofit, and industrial infrastructure are included. Don't forget, the cost difference between two pathways depends on the cost assumptions. You can use the default cost assumptions if you want, but you can be sure that those costs won't turn out to be exactly right! So I encourage users to use the cost-sensitivity feature; taking into account the cost uncertainties will give you a more reasonable picture of future possible cost ranges, and ranges of cost differences.
For me, one key message from this tool is the importance of innovation support to bring down the costs of all the technologies that may be important in the future.
Media coverage - The Carbon Plan and the 2050 Calculator have had a little bit of media coverage in the last month, including a nice mention in an editorial in Nature magazine.
Some of the coverage has been so inaccurate, however, that one is forced to conjecture that the authors of two recent pieces in the Telegraph made little effort to check their facts. For example, Christopher Booker perpetuates the twaddle of a blogger who invented the assertion that the 2050 calculator 'had been designed on the assumption that, with wind power, Britain would require much less energy, because we would have become more “energy efficient”, by insulating our homes and so forth'. This is complete twaddle, as anyone who takes the time to actually look at the open-source calculator can confirm. The user is perfectly free to combine any choice of energy-efficiency measures with any choice of energy-supply mix. Yes, the government's published pathways combine "green" energy sources (eg nuclear and wind) with energy-efficiency choices. But the calculator does not 'assume' or 'force' this choice. You can easily make high-fossil-fuel pathways with strong energy-efficiency action, if you want. It's all up to you, as the user. I think it's an awesome piece of "open-source policy development", and I'd like to congratulate the civil servants who did it, and thank all the hundreds of experts and volunteers who have helped them in their work. I really hope this open, factual tool can now be constructively used by politicians and opinion-formers to help public engagement with the issues of long-term energy security and climate-change action.

Come and work at DECC!

2011-09-21T13:55:00.000-07:00

DECC is advertising roughly a dozen posts for engineers and scientists.Here's the advertisement for 7 grade-7 engineers and 1 grade-6 engineer and 1 SEO. The closing date is 30 September 2011.More jobs are advertised here, including science/engineering specialists to work in the Office of Renewable Energy Deployment.Come and join us, it's a great place to work!

Public debate about 2050 Pathways

2011-03-05T16:19:00.000-08:00

DECC is running a public debate, using the new 2050 Calculator, at blog.decc.gov.uk. The debate was opened by eight experts (Mike Childs, Friends of the Earth; Dustin Benton, Campaign to Protect Rural England; Prof Nick Jenkins; Mark Brinkley, Housebuilder's Bible; Duncan Rimmer, National Grid; Dr David Clarke, Energy Technologies Institute; Keith Clarke, Atkins; Mark Lynas, author), who presented and discussed their preferred pathways within the calculator. It's now open to the public to join in. In a couple more days, the opening panel will wrap up their conversation; it'll be interesting if they can achieve consensus on one or two pathways.

The panelists and their pathways

Mike Childs: demand highly curtailed and very high renewables
In Mike’s pathway, 20% of primary energy will be imported and emissions will be 80% below 1990 levels in 2050.
Mike’s pathway in more detail

Dustin Benton: demand highly curtailed and high renewables
In Dustin’s pathway, 33% of primary energy will be imported and emissions will be 81% below 1990 levels in 2050.
Dustin’s pathway in more detail

Professor Nick Jenkins: maximum electrification of homes and industry
In Nick’s pathway, 54% of primary energy will be imported and emissions will be 82% below 1990 levels in 2050.
Nick’s pathway in more detail

Mark Brinkley: lots of bioenergy
In Mark’s pathway, 66% of primary energy will be imported and emissions will be 79% below 1990 levels in 2050.
Mark’s pathway in more detail

Duncan Rimmer: mix of CCS, nuclear, renewables and all cars electrified
In Duncan’s pathway, 60% of primary energy will be imported and emissions will be 81% below 1990 levels in 2050.
Duncan’s pathway in more detail

Dr David Clarke: mix of CCS, nuclear and renewables
In David’s pathway, 56% of primary energy will be imported and emissions will be 81% below 1990 levels in 2050.
David’s pathway in more detail

Keith Clarke: high electrification of transport, homes and industry
In Keith’s pathway, 58% of primary energy will be imported and emissions will be 77% below 1990 levels in 2050.
Keith’s pathway in more detail

Mark Lynas: lots of geosequestration
In Mark’s pathway, 78% of primary energy will be imported and emissions will be 80% below 1990 levels in 2050.
Mark’s pathway in more detail

Version 2 of the 2050 Calculator

2011-03-02T14:58:00.000-08:00

On Thursday 3rd March, DECC is going to be publishing version 2 of the 2050 Pathways Calculator, along with an updated version of the calculator that runs in your browser - now including energy flow diagrams and maps showing land areas and sea areas.

We're also publishing a simplified "My2050 simulator", aimed at engaging a wider audience in this open-source conversation about energy policy.
To celebrate these publications, I'll be on a live Guardian blog on Thursday 3rd March at lunchtime.

Downwind faster than the wind

2010-12-04T05:40:00.000-08:00

In July 2009 I wrote a post about wind-powered vehicles that travel directly downwind faster than the wind, giving links to videos explaining why this surprising idea is in fact possible.
I've now noticed that in July 2010 a fantastic team of enthusiasts fasterthanthewind.org indeed demonstrated a single-person wind-powered vehicle that goes more than twice as fast as the wind, directly downwind. Don't you just love engineers?!

Science, Engineering and Technology Award for DECC 2050 Pathways Team

2010-12-03T00:54:00.000-08:00

At the Civil Service Awards last month, the Science, Engineering and Technology Award was won by the DECC 2050 Pathways Team for their work, which I highlighted in July.
From right to left, the photo shows Gus O'Donnell (Cabinet Secretary) giving the award to Katherine Randall, Tom Counsell, Clare Maltby, and James Geddes at Buckingham Palace. (To their left are two staff from the Government Office of Science.)

Now available in Japanese! - "Sustainable Energy - without the hot air"

2010-11-14T19:48:00.000-08:00

Many thanks to Katsunori Muraoka!

持続可能なエネルギー—「数値」で見るその可能性 [単行本]

Making numbers stick - desalination, melting, and boiling

2010-10-17T06:41:00.000-07:00

I'm always looking for new ways to make physical numbers memorable.

One method is to use a picture (eg nuclear waste, per person, per year) [page 170, SEWTHA]
Another general rule is to choose units such that the answer to be remembered comes out between "1 unit" and "200 units", because smallish numbers are easier to remember.
Another idea is to reexpress the quantity in completely different units, which may be more familiar and more memorable, as illustrated in this earlier post where I converted an incomprehensible 20 x 10²² J into a hopefully more human-friendly ocean temperature rise of 0.2 degrees C.

I'd like to give a few more examples of this trick, all converting unmemorable numbers in awkward units into temperature rises.
Example 1: the cost of desalinating sea water. [This method of making it stick came from Jim Gill, Chancellor of Curtin University, via Sam Wylie.] In SEWTHA (p 93), I report that desalination has an energy cost of 8 kWh per m³. A nice way to make this number more meaningful is to work out what temperature rise you would get if the same energy were put directly into heat in the same volume of water. The answer is ((8 kWh) / (1000 litres)) / (4.2 ((kJ / C) / litre)) = 7 degrees C.
This result brings home that if the desalinated water is going to be used for a shower or for cooking, the energy cost of the desalination is fairly tiny compared to the energy that will be used later in the water's lifecycle.

Example 2: melting ice. The latent heat of melting of ice is 6 kJ/mol, or 333 kJ per kg, a quantity I have never been able to memorise... until now! Using the same trick as above, we can convert this into an equivalent temperature rise, by dividing by the heat capacity. The answer is "the latent heat of melting of ice 'is' 80 degrees C".
I don't think I'll forget that number! It really brings home why mountaineers spend so much time melting snow. The energy to melt the snow is roughly the same as the energy to bring the melted snow up to boiling point!
Example 3: vaporizing water. We can apply the same trick to the heat required to vaporize water (2258 kJ/kg). The answer is (2258 kJ/kg) / (4.2 kJ/kg/C) in C = 538 C. This number violates the "should be between 1 and 200" rule, so it is not super-memorable, but it is quite striking, isn't it - whereas near-boiling water is 373 degrees above absolute zero, the energy required to actually boil it is equivalent to another 538 degrees of temperature rise! Maybe the best way to obey the "1-200" rule is to reexpress this heat once more, comparing it to the energy required to bring the water from 0 to 100 C. It is bigger by a factor of 5.4. So "the time for the kettle to boil itself dry is about 5 times the time taken to bring it to the boil".
Here ends the lesson.

'smart ways of seeing numbers' - the BBC like the 2050 Calculator!

2010-09-08T13:26:00.000-07:00

In The BBC News Magazine, Go Figure, Michael Blastland says:
"If you've somehow missed it elsewhere, the DECC 2050 energy calculator is worth looking up."
Hurray!

New Energy Future

2010-09-03T13:50:00.000-07:00

There's a new video on the Independent's website, made with the support of Channel 4 and Shell. It's one minute long, and, as seems to be traditional now, features me talking about energy and lightbulbs.
There's also a linked article in the Independent by Steve Connor, on "why achieving a cleaner energy economy involves a series of difficult choices", which quotes Sustainable Energy - without the hot air.

The 'zero' charger's footprint (Hot Air Oscars nomination, greenwart)

2010-08-10T00:40:00.000-07:00

Here is a nice blog post by Blue Lyon, discussing the energy cost and money 'savings' offered by AT+T's recommendation to Turn your iPhone green with a new ZERO Charger.
Blue Lyon works out that the charger, which claims to use less power on standby, might pay for itself in 44 years, assuming it was displacing an old charger using 0.26 W, left plugged in all the time.
The makers of 'ZERO Chargers' are therefore nominated for the Hot Air Oscar for flagrant exploitation of gullible consumers.
One way to think about this is simply to look at the energy cost of delivery alone, assuming that the delivery involves one van making a 5-mile trip. Typing this into my firefox browser
5 miles / (13.1 miles per US gallon) * 10 kWh per litre in kWh
gives 14 kWh of transport energy to deliver the greenwart. That corresponds to the energy used by leaving the old charger in for 6 years.

2050 Calculator Tool at DECC

2010-07-29T00:51:00.000-07:00

I'm delighted to report that the Department of Energy and Climate Change has published the 2050 Pathways Analysis, which illustrates six possible energy pathways to achieve secure and affordable energy supplies in the UK while still hitting the 2050 target of reducing emissions by 80 per cent on 1990 levels.
These pathways were constructed with the engineering-based 2050 Calculator, which is now available as an online tool, and as a monster-spreadsheet that you can download, play with, and improve.
The Department is encouraging people to enhance this open-source tool, ideally before October 2010, so that it can in due course be used to engage civil servants, politicians, and the general public in 'grown-up' conversations, as Chris Huhne puts it.
The tool allows the user to explore the consequences - in terms of security-of-supply indicators and greenhouse gas emissions - of any combination of demand-side choices and supply-side choices. The intention of this 'play Secretary of State for Energy and Climate Change' approach is not to imply that the energy system could or should be centrally planned, but to help people understand the range of possibilities that are open to us; the trade-offs; the common themes shared by energy pathways that add up; and the scale of action required.
Here's one journalist's reaction to the tool [Independent]. And the Guardian. To understand what's going on behind the simplified front-end, please read the 2050 document and dive into the monster spreadsheet.
I'd like to praise James Geddes and Tom Counsell for their outstanding work in producing this tool, along with Jonathan Brearley, Graeme Cuthbert, Jan Kiso, Katherine Randall, Clare Maltby, and the whole 2050 team at DECC.

Ocean heat content, and useful units

2010-05-28T10:06:00.000-07:00

The recent post at realclimate about measured increases in ocean heat content has an interesting graph whose y-axis is labelled in spectacular units, 10²² J. Even exajoules are not that big! (1EJ = 10¹⁸ J)...
One comment on that blog suggested it would be good to re-express in other units that are more familiar - say degrees Celsius, or watts per square metre.
Here goes...
The graph shows the ocean heat content increasing by about 20 x 10²² J in 40 years.
First, let's express the change in heat content as a average rise in temperature of the top 700 metres of the ocean (which is what was actually measured to make these graphs!).

Temperature rise = (Heat content increase) / (Volume of water) /
                         (Heat capacity)
                 = 20 x 10²² J / 
                   (350 x 10⁶ km² * 700 m) / 
                   (4.2 x 10⁶ J/K/m³)
                 = 0.19 K (or 0.19 degrees C).

Second, let's express the rate of increase in heat content in terms of a net power per unit area required.

Power per unit area = (Heat content increase) / Time / Area
                    = 20 x 10²² J / (40 years) / 
                      (350 x 10⁶ km²)
                    = 0.45 W/m².

This can be compared with other things measured in the same units - see for example pages 20 and 170 in Sustainable Energy – without the hot air.
Hope this helps!

SEWTHA online - Index added

2010-05-09T14:06:00.000-07:00

I've added an alphabetical index page to the html edition of Sustainable Energy - without the hot air. I hope this helps! This index is identical to the version in the paper edition of the book, except that the page-numbers are clickable hypertext links.

Wind farm wakes

2010-01-20T15:19:00.000-08:00

I'd like to highlight a stunning photograph and an interesting paper.

The image shows clouds forming in the wakes of the front row of wind turbines of Horns Rev wind farm.
The paper, Wake effects at Horns Rev and their influence on energy production, by Mechali, Barthelmie, Frandsen, Jensen, and Rethore, describes measurements of the effects of these wakes on wind power production.

The message of the paper is interesting. The downstream wind turbines lose 20% or 30% of their power, and sometimes even more, relative to the front row. The spacing of the turbines is 7 diameters.

'withouthotair' - Alternate website

2010-01-05T13:38:00.000-08:00

The website withouthotair.com has gone down today (5 Jan 2010) and I am not sure why... anyway, there is a backup website at www.inference.phy.cam.ac.uk/withouthotair/. (Also known as tinyurl.com/sewtha.)
Thanks to friendly people for pointing out the problem.
Apologies for any inconvenience!

Late entry by The Times for the 2009 Hot Air Oscars

2009-12-23T10:41:00.000-08:00

In July 2009, I nominated two newspapers for the Hot Air Oscar for Most inaccurate numbers in a right-wing newspaper.
A late submission has arrived, nominating The Times for their laughably inaccurate statement about solar power.
The US Energy Department has calculated that a 62-square-mile (160 sq km) parcel of the Mojave [desert]... receives enough sunlight to power the entire country.

Anyone who has seen SEWTHA page236 will know this statement is wrong. The average power of tropical desert sunshine is about 250 W/m² [see page 46]. Multiply by 62 square miles and you get 40 GW. That is far smaller than US power consumption, which is about 3700 GW (if they mean power in all forms) or 420 GW (if they mean electricity only).
Being more realistic, we should use a power per unit area of 15-20 W/m², since that's what real solar power stations offer. At that power per unit area, 62 square miles would give you just 2.4-3.2 GW.
What is it about journalists, areas, and squares? One of the ealier nominations for this Hot Air Oscar also featured an incorrectly reported area!

Eat bacon and ride a bike!

2009-12-16T16:49:00.000-08:00

About 8 months ago, I made a short video with the help of Cambridge University, called "how many lightbulbs" [1]. This week, Cambridge University has published another 6-minute video in the same series - it's fantastic, and it's called Professor Risk. ← click this link to go to the movie in its own page.

The Energy Game

2009-11-29T01:27:00.000-08:00

Some super people have been developing ways of presenting energy numbers and engaging the public and policy-makers in consensus-building conversations.
The next 'Energy Game' will take place at the Science Museum in London at the Dana Centre on 3 Dec 2009 at 7pm-9pm, organized by Serious Change.

How to boil water - the sequel

2009-11-01T15:31:00.000-08:00

One year ago, I wrote a blog titled how to boil water, which linked to a short essay, "how much is inside hot water?". Over the subsequent 12 months, a flood of emailers have requested that I answer their follow-up questions: "does it make any difference if the lid is on the pan?" and "how does a microwave compare with the pan and the kettle?". Dutifully, I did experiments this Sunday, and this link describes the results in full.
The conclusions are that keeping the lid on the pan while boiling water saves about 3%; and that the microwave is a hopelessly bad way to boil water for making pasta.

Challenged by Carbon

2009-10-18T02:26:00.000-07:00

I'm reading Challenged by Carbon: The Oil Industry and Climate Change by Bryan Lovell.
Bryan Lovell is a geologist who has worked in academia and the oil industry for decades. This is an unusual book, intertwining two stories, one of them 55 million years old, and one less than 55 years old. I've not heard either story told before, and both are fascinating.
For the older, slower story, Dr Lovell delves into the details of the geological history of Iceland, the North Atlantic, and the North Sea. He describes how local heavings of the planet's stomach have caused a sub-ocean ridge between Scotland and Iceland to slightly rise and fall, having knock-on effects on ocean circulation and global climate; how slight variations in the average intensity of sunlight in the Northern hemisphere cause changes in climate on a timescale of 20,000 years which can be detected in sedimnetary rocks; and, crucially, how a large natural rapid release of carbon into the atmosphere, 55 million years ago, led to an enormous global warming event, raising the temperature of the water at the bottom of the ocean by more than 4 degrees C within roughly 10,000 years.
The younger, rapidly-moving story is the `insider's view' of how the oil industry, in the last 15 years, changed its mind about human-caused climate change. Starting from positions of climate inactivism (by which I mean "yeah, it may be true, but there's lots of uncertainty and there's no point doing anything, and we oppose greenhouse-gas-reduction treaties") or outright denial, the big oil companies, driven by the science, changed their tunes. First, in 1997, Shell and BP, then, in 2004, ExxonMobil came round to the view "that there is a big problem and that urgent action is required". Lovell knew all the key players well, he was there at the dinner-table discussions where this "Atlantic divide in Big Oil" heaved to and fro, and he hints at the bruising personal conflicts that took place as the oil experts argued about the science. Lovell identifies a particular BP-ExxonMobil debate held by the Geological Society's Petroleum Group in London in 2003 as a turning point in the argument, and describes at length this conversation, whose backdrop was the start of the 2003 Iraq war.
The two stories are connected in multiple quirky ways: the ancient global warming event was probably associated with an uplifting of Scotland that led to the deposition of the North Sea oil fields, from which the oil-folk derived much of their recent wealth; and, more significantly, Lovell describes the 55-million-year-old global warming event as one of the pieces of evidence that helped swing the climate-change argument: oil-men believe what they see in the rocks, and those rocks give uncomfortable evidence for what happens when a large amount of carbon is suddenly released into the atmosphere.
Both stories have the feeling of incompletely-solved detective mysteries. Where did the carbon come from in the ancient global warming event? Was it methane hydrates? Volcanoes? Or some other form of carbon deposit? Was it Iceland that precipitated the global transformation? As for the present-day conversion story, Lovell leaves the reader wondering whether the detective story is yet over - yes, some oil companies greened up their public facades in 2003, but have they reverted to business as usual behind the scenes? And what about the rest of the oil industry?
In the second half of the book, Lovell indicates how he hopes the drama will unfold: "government intervention is essential" in relation to the transition to the low-carbon economy; "concerted action" is required from all oil companies; oil companies should turn their remarkable technical skills to a new waste management business: capturing and storing carbon, especially carbon from coal power stations.
Now, I love physical numbers, so let's recap some of the key numbers for carbon capture. A standard unit of carbon capture and storage is "the Sleipner": thanks to Norway's implementation of a carbon-emission tax of $55 per tonne of CO₂ (which can be compared to today's EU market price of 14.10 euros per tonne), StatoilHydro is storing 1 Mt CO₂ per year in the Utsira saline aquifer under the North Sea. A 1-GW coal power station, running all the time, produces roughly 7 Mt CO₂ per year. So every 1-GW power station would require roughly 7 Sleipners, and the cost to the consumer for electricity from that source might be in the ballpark of an extra 4p per kWh of electricity (similar to the present subsidy for wind power in the UK). The scale of the waste to be stored is worth mentioning. The volume of 7 Mt CO₂ (the approximate annual waste from 1 GW coal power station), after it's been compressed to the same density as water, is three times the volume of the great pyramid at Giza. If Britain were to build, say, 33 GW of `clean coal', the volume of compressed waste that would have to be pumped through pipelines and into rocks under the North Sea would be 100 great pyramids per year; or, to put it in personal terms, 13 litres per day per person in the UK, every litre of this waste CO₂ having the same weight as a litre of water.
This book is fascinating reading.
David MacKay, 18 October 2009

Regenerative braking works!

2009-09-19T08:57:00.000-07:00

I had a brilliant tour of the Modec electric delivery-vehicle factory in Coventry, and they let me take a one-hour test-drive in an instrumented vehicle (pictured above).
The vehicle had perfectly good acceleration and its response to the pedals has been engineered to make it feel just like a 'normal' vehicle.
For me the most exciting details from the data from this 3.5-ton vehicle were: 1) three headline numbers - maximum power 80 kW; maximum regenerative power 20 kW; typical power at top speed 40 kW; 2) one nicely measured deceleration event from top speed to zero, which allowed an estimate of how efficient the regeneration is at capturing kinetic energy (the answer was that it was better than 50%; and the Modec engineers mentioned a redesign of the transmission that might further improve this efficiency). 3) overall regeneration figures, showing that the regenerative braking recovered roughly 15% of the energy used during the whole test-drive. The graph above shows by the green area the energy recovered, and by the red area the energy that went out from the battery.
Thank you, Modec!
Full story with factory tour images and data

The carbon-neutral flexible friend - Hot Air Oscar nomination for Barclays

2009-08-29T11:44:00.000-07:00

Oh dear... The 'green' twaddle keep on pouring out of the commercial world...
Theo Markettos writes: "I'd like to nominate Barclays for a Hot Air Oscar:
We've launched a new carbon-neutral debit card, which is being rolled out to our debit card users as their current ones expire. ... blah blah ... The Carbon Neutral Company ... blah blah ... reduce carbon emissions in the developing world.
This effectively balances out the harmful emissions of the card's manufacturing process by preventing the release of the same amount of greenhouse gases somewhere else."
Theo continues: "Given the huge influences economics and finance can have on behaviour towards climate change, I'm so glad this bank is focusing on the contribution of the small piece of plastic, silicon and epoxy in my pocket."

Yes, indeed - a fine nomination for the Hot Air Oscar for best emulation of bailing the Titanic with a tea-strainer.

The future of energy

2009-08-29T05:09:00.001-07:00

The International Herald Tribune and New York Times published an article featuring my energy consumption versus population density diagram.
Here is the article -
Illuminating the Future of Energy
and here are several alternative versions I made of the diagram -

Servants, LEGO, and Kindles

2009-08-28T11:35:00.000-07:00

I'm happy to announce that Sustainable Energy - without the hot air is now available for the Kindle. A lot of Kindle users have been asking for this. I hope it works nicely!
Some helpful correspondents sent me some nice links to other people's estimates of the energy output of a human slave. I've added these links to the SEWTHA wiki. If you have additional data or facts relevant to the book, please add them to the wiki. Thanks!
And last but not least, I've been brainstorming with friends about how to make games for understanding energy and for consensus-building. One such game has already been designed using lego to represent energy inputs and outputs.

A new graph, showing countries' power per unit area

2009-08-01T14:08:00.001-07:00

When I gave my energy talk in Cambridge two weeks ago, one member of the audience objected to my figure (page 13) showing per capita emissions by country. It would be fairer, she said, to show the emissions or energy consumption of each country per unit land area. (Guess her nationality... Australian!) I've made a few figures following her suggestion, and I'm displaying my favourite here. This figure shows population density on the horizontal axis and power consumption per person on the vertical axis. The diagonal green lines indicate the power consumption per unit land area, in W/m². This is precisely the same unit in which I measured or estimated the power per unit area offered by renewables (page 112). Most renewables offer between 0.5 and 5 W/m².
Conclusion: All countries whose power consumption per unit area is bigger than 0.1 W/m² are countries who should expect renewable facilities to occupy a significant intrusive fraction of their country, if they ever want to live on their own renewables. Countries with a power consumption per unit area bigger than 1 W/m² (eg UK, Germany, Japan, Netherlands, Belgium) would have to industrialize most of their countryside, if they want to live on their own renewables. Alternatively, their options are to radically reduce consumption, use nuclear power, and/or to buy renewable power in from other countries.

(Image can be downloaded from here)

Air traffic visualized

2009-07-31T03:19:00.001-07:00

There is a very nice you tube video showing all planes flying during a 24 hour period. I have extracted a frame every 5 seconds to make an animated gif which you can view on this page - I find that my animated gif, which goes about 60 times faster than the youtube video, allows you to perceive some things that are hard to perceive in the video.

"Diluted" Carbon dioxide is "less harmful" - Hot Air Oscar nomination

2009-07-29T04:50:00.000-07:00

Get ready to splutter with astonishment... This Reuters feature about UK Carbon Capture and Storage, featuring the switching on of a new OxyFuel combustion burner contains an astonishing sentence:
The Doosan Babcock burner will not attempt to store CO₂ but release it in a diluted, less harmful, form into the atmosphere.
Presumably a Nobel prize is in order, for the discovery that the climate-change impact of CO₂ is reduced by diluting it.
I'm not sure to whom this Hot Air Oscar nomination would be directed - to Doosan Babcock? to the journalist? - but anyway, this must be a strong contender for the Hot Air Oscar for most jaw-dropping twaddle about greenhouse gas emissions.

Thanks to Paul for the nomination.

Eco eco eco! And super-efficient too (Hot air oscar nomination)

2009-07-29T01:28:00.000-07:00

A Hot Air Oscar nomination for boldest appropriation of the word eco goes to Australian company "todae" for their promotion, in their "eco-lighting" section, of "Super Efficient" Halogen 35W downlights. Their product description explains how awful standard halogen lights are, wasting 80% of the energy as heat. These super-efficient halogen replacements for halogen bulbs will save 30%.
Now, it may seem harsh to nominate an energy-saving product for the Hot Air Oscar when there are so many other "eco" scams out there which save much less energy than this (for example, BMW's "EfficientDynamics" innovations). Well, please keep the nominations rolling in. I notice in Toady's web page (just to the right of Galadriel there) that they are also promoting miniature solar panels. Perhaps more nominations can be harvested right here!

Thanks to Carl Myhill for the nomination.

Wouldn't it be better? No, I don't think so! (Hot Air Oscar nomination)

2009-07-27T11:11:00.000-07:00

The website realtimecarbon.org encourages people to be aware of the carbon intensity of the grid, saying "Wouldn't it be better if we could use power when it's greenest?". I am pretty sure that the answer to this question is No!
Imagine, for the sake of simple discussion, that we have a country in which on average half the electricity comes from baseload nuclear power (intensity, 20 g/kWh) and half from demand-following gas (470 g/kWh). And that at night, demand is 60% of the average, and 83% of the electricity comes from nuclear. And that in the day, demand is 140% of the average, and 36% comes from nuclear.
Under these assumptions, the nighttime grid intensity is 95 g/kWh, and the daytime grid intensity is 310 g/kWh.
People using the RealTimeCarbon service will be advised by the red flashing "carbon alert" icon to avoid using electricity during the day, and will be rewarded with feelings of green smugness if they go to great lengths to use electricity at night instead. They may delude themselves into claiming that they have reduced their carbon footprint. You could even imagine them selling carbon offsets based on this sort of electricity-consuming time-travel. But, in the cartoon world that I have just described, the time at which you use electricity makes no difference at all to the carbon emissions! Imagine that 1000 people all earnestly follow the RealTimeCarbon guidance and turn on their 1kW toasters in the middle of the night instead of during the day. What happens? Well, in response to the increase in demand, an extra 1MW of electricity is generated while their toasters are on; and this electricity (in my cartoon world) comes from the gas power stations being turned up just a little bit, whether they turn their toasters on at night or in the day. The true marginal impact of their consumption is 470 g per kWh, whenever they consume.
Now, I am not saying that this cartoon is a faithful representation of what's going on in the UK. Maybe in the UK there are some times of day that are "good" times to use electricity, and others that are "bad". But I think this cartoon proves that "knowing the grid average" doesn't tell you anything useful about that. And I think that the cartoon is a fairly good cartoon of the UK, since in the UK much of the really low-carbon electricity is wind and nuclear, both of which are (at present) not demand-following.
Moreover, I think that if people go to great trouble to check RealTimeCarbon for guidance on "when it is ok to consume", the end result may be a worsening of the UK carbon footprint! Here's two arguments why:
(1) I can imagine people inconveniencing themselves in order to switch on their equipment at night - their inconvenienced lifestyle may well use more energy (for example, when they wait up late for the RealTimeCarbon to go from red to green, they may keep the lights on for longer at night!);
(2) If people think that their electricity is "green" they may give themselves permission to consume more of it. (I know some people argue, for example, that "their electric car is powered by wind, therefore they can drive as much as they want, and it doesn't do any harm to the planet".)
I therefore nominate RealTimeCarbon for a Hot Air Oscar for "Best intentioned but most useless consumer-engagement".

Thanks to Kim West for pointing me to the website and asking questions.

PS - I posted a message on the realtimecarbon forum 3 days ago, querying another aspect of their methodology, and there has been no response.

Table for one

2009-07-27T10:33:00.000-07:00

INCPEN, The Industry Council for Packaging and the Environment, have produced a super leaflet called Table for one. It is a detailed document full of numbers estimating the energy footprint of one typical British person's food.
All the numbers are expressed in MJ per week. There's lots of nice diagrams, some showing the breakdown of the energy footprint of, say "Snacks" between food supply, primary packaging, transport packaging, transport from factory, retailing, travel to shops, home storage, and home cooking; and some showing summary numbers.
The one below summarises how much energy the average person gets from all their food (73 MJ/week (2.9 kWh/d)), how much it costs to produce and deliver it (337 MJ/week (13.4 kWh/d)) and how much energy is used to produce the packaging (35 MJ/week (1.4 kWh/d)).

The final figure below shows the breakdown of the footprint by food type, and there is a clear message about meat consumption (as I guessed in my book): meat has a bigger energy footprint than any other foodstuff. [They were assuming that the average person gets 7 MJ per week (1,700 calories per week, or 242 cal per day) of energy from meat; this is a weight of 1029 g per week (147 g per day). For comparison in Ch 13 I assumed a carnivore ate 227 g per day.]

It's nice to see an industry publishing such clear energy-footprint numbers! A copy of "Table for one" (pdf) is sitting on my website. I assume INCPEN don't mind my sharing it there.

Moon, and Age of Stupid

2009-07-26T11:59:00.000-07:00

This post is fairly off-topic for a sustainable-energy blog, as it is a review of a film that I enjoyed, and would like to recommend. Moon is a film about the life of a man, Sam, working for the biggest eco-energy company, mining helium-3 on the moon.
I am happy that all I knew about this film was that "Sam was lonely on the moon". The only review I read was Roger Ebert's, and he (good for him!) didn't spoil the movie by revealing its plot.
I recommend that you read no reviews of the film (apart from Ebert's), and don't even watch trailers for this film. Even looking at the strap-line on a poster for the movie may reveal more about the movie than you really want to know.
To make this post increasingly on-topic, I'd also like to recommend Age of Stupid. I wrote a review of it after seeing its UK premiere, of which I quote the opening paragraph here.
"The Age of Stupid" is a splendid film. Here's what sets it apart. Whereas many documentaries interview each subject briefly, on a single topic, "Stupid" slowly unveils each character and their web of relationships. The principal characters are real people, whose life-stories relate to the topics of climate change, energy policy and consumerism in multiple fascinating ways.
Both are great films, thoughtful, with twists, and thought-provoking.

Where the wild things are

2009-07-25T09:16:00.001-07:00

In SEWTHA, I included, as a joke, a map titled "Where the wild things are". The map shows in white the areas within 2km of human habitation (and thus of course excluded from wind farm development). It shows in black the areas that are more than 2km away from human habitation; these areas are thus tranquil, and also inappropriate places for wind farms. Wind farm development is to be encouraged in all other areas on the map.
Some readers have failed to understand my joke; that amuses me.
What's even funnier is the map produced by the RSPB, "to ease conflict between wind farms and wildlife" (October 2006).
This image shows their map, and the painfully funny thing is how similar its message is to my joke-map's. Almost every good location for wind in Scotland is excluded! - Almost all the islands are given a "sensitivity rating" of "4 high" (the maximum), with the exception of the single island of Jura, which is mainly judged "medium"; most of the highlands are also "high sensitivity". The only really promising locations for wind that squeak through below "medium sensitivity" are the Mull of Kintyre and the southern coast from Glasgow to Stranraer.
How is this map meant to relate to last week's RSPB announcement that the Renewable revolution is overdue?

Two exciting things (DII and DWFTTW)

2009-07-22T11:14:00.000-07:00

The first thing I got excited about recently is the news announcement that roughly 20 big German companies are talking about investing €400 billion in the Desertec Industrial Initiative. What is thrilling about this announcement is that it involves a sum of money that is in the right ballpark for a genuine plan to get off fossil fuels. So often, government announcements have involved 1 million here, 10 million there, and (rarely) 100 million. I reckon the cost of putting together a new energy system for the UK must be roughly 400 billion pounds, or 10 billion pounds per year from today to 2050. This is much more than millions; but it is still perfectly affordable, given that we already spend 80+ billion per year on energy and 80+ billion per year on insurance. I'd love to see details of what the German companies think they could buy for their 400 billion euro.
The second exciting thing was to discover, thanks to James from Isentropic, what I now consider to be the two best videos on ther internet. Namely: Downwind Faster than the Wind (DWFTTW) [which demonstrates that it is possible to make a wind-powered vehicle that goes directly downwind faster than the wind] and Under the ruler faster than the ruler [which explains with a nice simple model how faster-than-wind travel works].
What intrigues me philosophically about the wind-powered-travel expositions is that it reveals how fragile and weak "understanding" can be: I thought I understood wind-powered travel, and I already knew about wind-powered vessels that can sail directly upwind (eg, Revelation II, pictured). But I got the answer to the question "is DWFTTW possible?" wrong! - even though the principle by which upwind travel works is just the same as the principle of DWFTTW travel. So it seems that when I "understood" upwind travel, what I really did was append to my stack of physics heuristics another heuristic, permitting upwind travel; I didn't add a piece of knowledge that was capable of working in new situations.

RouteRANK

2009-07-21T09:13:00.000-07:00

RouteRANK provides a journey-costing service, which tells you all the different ways of getting from A to B, how long it will take, how much it will cost, and how many kilograms of CO₂ will be emitted. For any A and B in Europe. The image below shows the results for a "Cambridge to Edinburgh" query. Cute! I wish it displayed "energy used" too.

Most inaccurate numbers in a right-wing newspaper - Hot Air Oscars

2009-07-19T09:28:00.000-07:00

Well well! Ed Miliband's announcement of the government's energy road-map has given rise to a remarkable pair of nominations for the Hot Air Oscar for inaccurate numbers in a right-wing newspaper. What's remarkable is that both pieces of poor journalism, in the right-wing press, make assertions about wind power that spin erroneously in favour of wind power!

Nomination 1

The Daily Mail says Research by the University of Southampton has found that a well-placed turbine could make enough energy to power 825,000 homes a year.
Hahahahaha! As usual, the units are wrong. [They should either say "One turbine" could power "X homes" (no "a year"), or "one turbine could make enough energy in a year to power X homes for a year". Why can't people get units right?] But the inaccuracy of "X" is the funniest thing. Realistically, a typical 2MW turbine with a load factor of 27% will produce 0.54MW on average, which, using the standard definition of "a home" (see p 329 for my rant on that topic) means that it can power 1000 "homes", on average. I think a better way to visualize the impact of one such turbine is to say that its output is equal to the total energy footprint (including transport and heating and electricity) of roughly 100 UK people.

Nomination 2

The Daily Telegraph has twice propagated another piece of twaddle concerning the area required for wind farms to provide "all Britain's energy consumption". First there is a letter from Anthony Ridge-Newman, Royal Holloway University of London, published Sept 2008, which says "The most startling thing is that scientists estimate all of Britain's energy can be supplied by an offshore wind area as small as 70 square miles", and that "Britain could be producing enough energy from wind to begin exporting to Europe within 10 years." "Startling" - yes indeed! You'd think you'd be sufficiently startled to check your numbers before writing to a national newspaper! And you'd think the newspaper might check the numbers sent in by its startled correspondents before wasting ink on publishing them. But no. The Torygraph has actually printed this "startling" (and false) meme a second time, this time in an "Analysis" piece authored by "Dave Andrews, head of the Claverton Group", published on 16th July 2009. He writes of onshore wind that "it needs an area of only 70 square miles to generate Britain's total power requirements". Crikey. Did the copy-editor do this to make the Claverton Group look like a bunch of fools? Apparently so, yes! - The Claverton site says the article as submitted said "a 70-mile by 70-mile square". Yes, that would be 70 times more accurate! For the record, (see my survey of UK wind farms if you want, where I show that UK wind farms, whether onshore or offshore, generate roughly 2.5 watts per square metre, on average), 4900 square miles of windfarms would generate about 32 GW on average, which is close to Britain's average electricity consumption (it's about 42 GW). If you want to produce "all Britain's energy consumption today" (ie transport and heating too) then you need about nine times the area, since Britain's primary energy consumption is about 300 GW.
The bottom line - the Daily Mail article is off by a factor of 825, and the Telegraph's rendition of Clavertonism is off by a factor of 70 or 630, depending on whether you allow energy to be confused with electricity. It's a close battle for these awards!
Keep sending in nominations.

Acknowledgements

I thank Christopher Booker for pointing out these two "lunatic" articles. Booker coyly didn't name the two newspapers responsible for propagating the twaddle.

Sustainable Energy Pirates

2009-07-05T09:57:00.000-07:00

I'm upset to discover that some criminal types have gone to considerable lengths to make and sell fake paperback versions of Sustainable Energy - without the hot air on amazon marketplace. [Photo above shows a pirate copy (left) alongside a genuine paperback copy of the book (right).]

This page shows photographs of an example pirate paperback alongside genuine paperbacks. If you bought SEWTHA from amazon marketplace, please check your copy. If it looks awful, maybe it's a pirate copy. (Some reviewers seemed to think that the genuine book looks awful too!) The genuine books look professionally produced and are on good quality paper. To check whether your book is a pirate, please look at the photos. If anyone has been sold one of these fakes, we urge you please to (a) ask amazon for your money back; (b) complain to amazon about the 'marketplace' criminals. Thank you!

Sustainable Energy news

2009-07-03T16:14:00.000-07:00

SEWTHA was published in the USA on May 1st. Last week, it was reviewed in Science magazine, and now some people who like SEWTHA have written a submission to slashdot "Solving the Energy Crisis by Tripling Electricity".
If you like this article and have a slashdot account, please click on the "+" button to help the article get promoted.
And finally, the third printing of SEWTHA has just come out, and it has got a NEW COVER (shown above). My publisher and I are very democratic about these things, and when the Guardian's Leo Hickman opened his review with the words "It has a crashingly dull cover and title", we were happy to respond to feedback. We hope you like the new cover! [full size image]
The third printing brings the number of copies printed to 30,000.

Visualizing wind farms for Cambridge University

2009-06-28T02:41:00.000-07:00

I thought it would be a fun exercise to see, on a map, whether we could imagine powering the University of Cambridge from local wind turbines. The University's average electricity consumption is 11.4 MW, and its gas and oil consumption is 8.7 MW. (That's the University departments and offices only, not the colleges.) If we switched our heating over to heat pumps and insulated all the buildings, maybe the total consumption could be covered by 16 MW of electricity. Probably about 72 MW of wind capacity would be required to produce 16 MW on average. That's about 36 big wind turbines of the standard 2-MW size in the photo above, which shows Red Tile wind farm.
This web page contains my notes and the map, which is reproduced below. [Please click on the map to see the whole thing.]

The left side of the map shows West Cambridge, with locations for wind turbines shown by the green and red circles. Exclusion zones are indicated by blue circles. I've assumed that turbines could be put alongside the motorway and that motorway noise would dwarf the turbine noise, so that smaller exclusion zones are appropriate near motorways.
The right hand side of the map shows the Red Tile wind farm to the same scale.
I don't know who owns any of this land, nor have I done any wind surveys, so no-one should take this map seriously.
It would cost roughly £70 million to put up these turbines.
If people don't like the idea of having iconic wind turbines ruining the tranquility of the M11, another option would be for the University to buy a 1.6% share of a new nuclear power station. That might cost £32 million or so.

The one-percent rule, leading to patriotic thoughts about the Falklands

2009-06-17T15:36:00.000-07:00

I wrote an article for the Guardian. I called it "The one-percent rule". They called it "Talk of 'kinetic energy plates' is a total waste of energy".

Here's the article I wrote.

I'd like to suggest a one-percent rule for news-articles about energy-saving gadgets or renewable energy systems. The rule says "a gizmo may be discussed only if it could lead to energy savings of at least 1%". I suggest this rule not because minnow-sized savings are
worthless, but because the public conversation about energy surely deserves to be focussed on bigger fish.

The latest piece of green twaddle that's wasting people's attention is
the story (15 June 09) about a new supermarket carpark that has "kinetic road plates" creating "green energy" from the motion of customers' cars.

I'm not saying that these systems don't actually work; perhaps they do save a little bit of energy that would otherwise be wasted in the brakes of the cars arriving in the carpark. But my suggestion is that these systems save so little energy, we shouldn't waste newspaper space on such stories. There must be more important things to discuss (assuming we are serious about getting off fossil fuels).

To prove my point, let's compare the energy that might be saved by the "kinetic road plates" with the total energy used by a typical trip to the supermarket. Let's guess that the kinetic road plates extract one fifth of the kinetic energy of the arriving car. For a car
weighing one ton travelling at 20 miles per hour when it hits the road plates, the extracted energy comes to 0.002 kilowatt-hours (kWh). Now, the energy used by the car, assuming it is driven 3 miles to and 3 miles from the supermarket with a fuel efficiency of 33 miles per
gallon, is about 8 kWh. The savings from parking at the green carpark thus amount to one four-thousandth of the energy used by the trip to the supermarket.

That's much less than one percent. So this "green energy system" is just eco-bling, creating a delusion of happy progress while distracting people from serious change.

What are some ideas that satisfy the one-percent rule? Well, there's lots of examples: a domestic solar hot-water panel will generate roughly 4 kWh per day of hot water, which is roughly 50% of a typical family's hot water consumption, and a bit more than 1% of their total
energy footprint. Example two: wind power - a ten-fold increase in Britain's wind turbines would produce on average 4 kWh per day per person, which is about 4% of our total energy footprint.

So solar panels and wind turbines deserve to be on the public's radar. Of course, solar panels and wind turbines are old news. So let me close by suggesting a new topic of conversation that also satisfies the one-percent rule.

When we are planning wind-farms, it makes sense to put them up first in the windiest spots, where the hardware will give the biggest return. So let's talk about wind-farms in the Falklands.

Mean wind speeds in the British overseas territory of the Falkland Islands are 9-11 metres per second, compared with 6-9 metres per second around the British Isles. 1250 3-megawatt turbines in the Falklands would probably produce an average power of 2.5 GW (or 1 kWh per day for every one of the Queen's 60 million subjects). That's roughly 1% of the total energy footprint of the United Kingdom.

Are there any problems with this idea? Well, first, as usual, the wind farms "would spoil the view". There's no free lunch. Serious renewable power requires industrial facilities in the countryside; the point of proposing wind-farms in the Falklands is to reduce the area of countryside "spoiled". The total area of the Falklands is a bit more than half of Wales; the area occupied by 1250 windmills would be about one twelfth of the Falklands. Sheep could, of course, still safely graze among the turbines.

Second, the average power produced by these windmills would probably exceed the electricity demand of the three thousand inhabitants of the Falklands, so we'd need to find other ways of using the power. A traditional way of handling the problem of excess electricity is to
produce aluminium. Iceland and Norway, for example, produce 1% and 4% of the world's aluminium respectively. The Falklands wind-farm sketched above could produce 1.5 million tons of aluminium per year - 5% of world aluminium production. Aluminium is just one example of
a storable product; the electricity could be used to make other energy-intensive materials such as magnesium and cement.

Notes
Mean wind speeds are given at a height of 50m.
Source: http://www.gaisma.com/en/location/port-stanley.html
http://www.gaisma.com/en/location/grytviken.html
I assumed the load factor of turbines in the Falklands would be 66%.

Addendum, in response to the flood of comments on the Grauniad site
Thanks for the feedback! (1) To the Falkland-wind-critics who point out that Aluminium production needs steady power... Yes, I'm aware of that; I thought of saying so in the article, but decided brevity was a virtue. What I would have added is "to smooth out the wind fluctuations, we could create pumped storage systems, or other energy storage systems, just like the four pumped storage systems in the UK (which were built mainly to help match inflexible nuclear supply to fluctuating demand). This would bump up the cost a little.
(2) As for the energy-cost of shipping materials to and from the Falklands, this is one of the striking things I learned when writing Sustainable Energy - without the hot air: those monster ships are amazingly efficient at transporting stuff - far more efficient than trucks. (Read about it on page 91.) I'm not saying that Falkland-wind is definitely a good plan - just that you need to check the numbers before knocking a plan simply for using international shipping.
(3) And finally, to the people who insist in enjoying the delusion that the power harnassed by these silly ramps would be significant if only I compared it with the power consumed by the supermarket instead of with the power consumed by the trip to the supermarket: no. Work out the numbers! Here is a rough stab at the calculation: As you can read on page 93, UK supermarkets consume 0.5 kWh per day per person. If every person visits their favourite supermarket once per 7 days, then their supermarket is consuming 3.5 kWh per personal visit. If the silly ramps manage (as estimated above) to provide 0.002 kWh per arriving car, then the silly ramps are covering less than one thousandth of the energy consumption of the supermarket. Cut the twaddle. These things are eco-bling, whichever way you look at them. All you need, to see this, are simple numbers. [The Falklands idea may turn out to be a bad idea too, but I hope people find it fun to think about.] David MacKay, Cambridge.

How much can one drinks bottle achieve?

2009-06-17T00:04:00.000-07:00

I'd like to nominate the belu bottle of natural mineral water for the Hot Air Oscar for the greatest ecological achievements by a 500-ml beverage container.
It's an incredibly long list, spanning the whole ecosystem. On the front of the bottle there are icebergs and a penguin. On the back, a field full of flowers and butterflies.

The bottle's achievements, in more detail:

It's the UK's first compostable bottle.
They can be composted back to soil in only 8 weeks - a million times faster than plastic bottles!!
Every bottle you buy provides clean water for one person for one month
It's the first bottled water that does not contribute to global warming
It is penguin approved
All profits go to clean water projects

Surely it is an honour simply to stand in the presence of such a vessel.

Hot Air Oscars nomination: Easy Being Green

2009-06-08T07:56:00.000-07:00

A nomination for most inspirational fluff on a bottle goes to Avra, Greek water manufacturers.
"It's so easy being green" ...on a plastic water bottle, in a country where the tap water is perfectly drinkable.
[From flickr, thanks to jinty for the nomination.]

Corrections and clarifications (Wind, Whitelee, Wales...)

2009-05-22T15:57:00.001-07:00

Perhaps I need to stop doing media interviews...
I wrote some notes about Whitelee recently. Last weekend, the BBC asked me to record some comments in advance of the official Whitelee switch-on. My comments focussed on the scale of renewables required to really make a substantial contribution to British energy consumption. Unfortunately my comments may have been misinterpreted - partly because I wasn't actually sure what I was being asked! The interview was recorded by a nice subcontracted interviewer who had been fed the 3 questions to ask me. The first question was "are the government's targets achievable?" ... with no indication of what targets the question referred to. The child poverty targets? "No more boom and bust"?
I answered the question assuming we were discussing long term climate targets. In one take I referred to "the government target of a complete decarbonisation of our electricity supply system by 2030." This was an error, as the government hasn't adopted that target (yet); it is the Committee on Climate Change that has indicated that they think almost-complete decarbonization of electricity by 2030 is essential.
As I have discussed in this article, if the UK is to get off fossil fuels, we need to be talking about big efficiency measures, probably lots of electrification of transport and heating, and big growth of 'green' electricity sources - for example, something along the lines of windfarms with size similar to the area of Wales, and a five-fold increase in nuclear power. Each of these two sources would deliver roughly 20 kWh per day per person.
Do I think Whitelee is a figleaf? Not at all. It's awesome, and it does generate real power, on average - enough to power hundreds of thousands of electric vehicles, for example - though not quite enough to "power Glasgow".

Wind farm power-per-unit-area data complete

2009-05-17T18:15:00.000-07:00

I have updated my data on windfarms.
I've gone through roughly 75 farms, finding the power per unit area. You can see the results here.
The conclusion is that many Scottish wind farms, located on hilltops, have powers per unit area of about 4 W/m². English and Welsh wind farms are in the range 2-3 W/m² for the most part, though there are a few in England below 2 W/m².
Incidentally, while looking at the windfarms, I had a think about the Braes of Doune photo above, which shows a windfarm ruining the view of Stirling castle. The distance from Stirling Castle to the wind farm is actually about 15km. The photograph subtends an angle of about 3 degrees. It is the sort of view you get through a 670-mm zoom lens.
The two summary figures from my wind farm survey are shown below. The top one shows power per unit area versus turbine diameter; the lower one shows it versus wind farm size. The point style indicates the type of windfarm location.

Acknowledgments
Thanks to Oswald Consultancy and the Renewable Energy Foundation for collating most of the power generation data and turbine specifications. All the original data can be found at OFGEM. Thanks to Ordnance Survey for their getamap service.

"Better than BS 7671 : 2008 IEE Wiring Regulations 17th Edition!"

2009-05-16T15:09:00.001-07:00

Friends have been asking "how is the book selling?" - I'm happy to report that Sustainable Energy - without the hot air has been doing quite well. On amazon.co.uk, its sales rank among all books has been wandering around the 100 mark for some time now. And in the list of the most popular Science and Nature books, it's at number 4, ahead of Dawkins' God Delusion, and (a great personal triumph, this) ahead of the IEE's renowned "On-site Guide; BS 7671 : 2008 IEE Wiring Regulations 17th Edition".

I made a graph showing how the sales rank of SEWTHA has evolved on amazon.co.uk and on amazon.com. The light vertical lines mark events, with the most significant ones being the Economist's review, the Cory Doctorow review, and the coverage by the Guardian, which took the sales rank to 47.

The latest piece of good news is that I've been elected a Fellow of the Royal Society. The Society's press release mentions me and the book, which is very nice of them!

Oh no! Green electricity spat!

2009-05-16T11:18:00.001-07:00

As I mentioned in another post, I switched from electricity-generator, Powergen, to "Good Energy", out of irritation at Powergen's perpetual greenwash.
Now I've learned from The Guardian that Good Energy may have been duping me with greenwash too!
One of the minor advantages of Good Energy over the competition was that they claimed to actually retire some ROCs (renewable obligation certificates), which has a genuine "additional" effect, as it increases (slightly) the financial incentive to people putting up renewable generation facilities.
However, according to the Guardian, Good Energy have not been retiring as many ROCs as their blurb led customers like me to believe. Oh dear.
Their blurb said things like:
"Good Energy goes above and beyond the percentage required by the government (8.9 per cent in 2008), by retiring an extra five per cent of ROCs (ie, 13.9 per cent in 2008)." but in fact, they've been retiring only about two per cent.
It's an awkward consequence of the slightly goofy Renewables Obligation system.
To get your subsidy for generating wind power, you have to cash in the certificates. (The certificates are then bought by brown companies like Powergen that are not generating enough renewables, to get them off the hook.) If you retire the certificates instead then you don't get any subsidy. So it's really hard to do anything "additional". People trying to do Good get no subsidy.
If Britain had a feed-in tariff instead, like Germany, I think this Catch-22 would be removed. Everyone who generated extra renewable electricity would be rewarded for doing so, and no-one else would be let off any hook thanks to their generation.
It's sad that Good Energy and Ecotricity are having this spat with each other. I was at a round table meeting in London, organized by the Ecologist magazine, attended by both the CEOs of both companies, and there, everyone seemed to be on the same side.
I think, going by the news article, that Good Energy have been naughty. And as a customer I feel a bit disappointed. My advice to Good Energy would be "stop trying to make out, through funny accounting, that you have been retiring 5%. Just give up on the retiring idea".

Whitelee powers Glasgow again

2009-05-16T03:02:00.000-07:00

Whitelee wind farm, the biggest wind farm in Europe, is to be completed and 'switched on' this week. And
the news says that the power company is applying to extend the wind farm to increase its capacity from 322 MW to 614 MW.
I mentioned the predicted output of Whitelee in my book (page 33). Since the predictions for Whitelee were one of the sources for my estimated wind-farm-power-per-unit-area of 2 watts per square metre, I thought it was a good idea to look at Whitelee's updated numbers.
When I was writing my book in October 2006, Whitelee's predicted output was said to be "enough to power Glasgow" (Independent, Oct 10, 2006). And now, the latest news says
that, with the proposed increase in capacity from 322 MW to 614 MW, the farm will... generate enough power for [all the homes in] Glasgow!
Curious, Alice might say. We run, and we stay in the same place?
Here are the new numbers.
With two extensions, the total number of turbines would be 221, the capacity would be 614 MW, and the predicted total output is "340,000 households", which in sensible units is 184 MW (assuming that "a household" is defined to be 0.54 kW). This implies a load factor of 30%. The area of the site (according to the Sunday Herald) will increase to 75 km². So the average power per unit area of the enlarged wind farm is predicted to be 2.45 W/m².
What is the honest relationship of Whitelee to Glasgow? (I think talking about 'households' is a bit misleading.) The predicted output of Whitelee, shared between the 616,000 people of Glasgow, would deliver 7 kWh per day per person on average. That's roughly 40% of the total electricity consumption of Glasgow, and roughly 6% of the total power consumption of Glasgow (that's 'total power' including transport, heating, etc; not just electricity).

Implications for the scale of wind farms required for a substantial contribution to British power consumption

If we assume Whitelee (including its planned extension) is representative of future big wind farms that could be built in Britain, here are some more numbers.

The government's 2020 target is for "33 GW" of wind capacity. That would require 54 more Whitelees. The area of those wind farms would be about 4000 km², about 20% of the area of Wales. The power delivered by those wind farms would be about 4 kWh per day per person, which is roughly 4% of the UK total power consumption today. (That's 'total power' including transport, heating, etc; not just electricity).
If we wanted to get 20 kWh per day per person from wind power, we'd need 270 Whitelees, which would take up an area of 20,000 km². That's roughly the area of Wales, or 8% of the area of the UK.

If we want to get off fossil fuels using renewables, we must expect those renewable facilities to be somewhat intrusive.

End notes (in anticipation of the responses people often make)

Yes, the wind-farm land in between the wind turbines can also be used for agriculture or other activities.
Yes, the output of wind farms fluctuates, so if we build wind farms we will have to do some other smart stuff, as discussed in chapter 26 of my book. For example, ensure that lots of smart [easily switch-off-and-on-able] demand is added to the grid, for example, charging electric vehicles and running heat pumps to make hot air and hot water.

Hot Air Oscars nomination: GO-GREEN

2009-05-08T10:34:00.000-07:00

We are happy to nominate for the "best GREEN advertising" Hot Air Oscar, the "Eco-Smart" organization in America who advertise "877-47-Go-GREEN" on the side of their tastefully green HUMMER.

Is David MacKay "trying to make wind sound useless"? Let's look at more data

2009-05-08T03:29:00.000-07:00

I'm delighted to see that the response to Sustainable Energy - without the hot air so far has been remarkably positive. There's just one or two folks who have become convinced that I am anti-wind, that I am deceitfully making wind sound worse than it really is; and they have been running round leaving comments on blogs (for example, you can find one lurking in the comments on this excellent article about the financial cost of wind power (the oil drum), who asserts "MacKay has made a serious error in his calculations of on-shore wind energy resources. ... Some of the wind farms initially built were in poorer locations but close to electric transmission lines, so his calculations are not good examples of what is possible in UK.")
I've written three blog posts about this topic already, encouraging people to provide real data rather than just spreading poisonous rumours. I've now worked through the ordnance survey maps and ROC register entries for about 15 windfarms around the UK, and included the data and maps in a presentation I made at a wind energy conference in St Andrews this week. I am still working on this; what I have focussed on so far is mainly the newest windfarms for which data is available, with the largest numbers of turbines, with biggest diameters, and mainly on scottish hilltops or welsh hilltops or near to the coast. The new data starts at slide 30 and is summarised on slide 41. These onshore wind farms have powers per unit area between 2 and 4.6 watts per square metre. To indicate the rough scale of windfarms required to deliver large amounts of power, I assumed in the book a power per unit area of 2 watts per square metre. So yes, there are windfarms that have powers bigger than 2 watts per square metre. Was I deliberately "making wind power seem worse than it is"? No. I chose 2 watts per sq metre as an estimate of what we could get if we put up lots of wind farms (with the area of Wales), which is obviously going to be less than the power per unit area of the very best spots. Yes, I willingly agree that if we want wind to make only a small contribution (for example, less than 1 kWh per day per person), then it would be appropriate to assume a higher power per unit area - perhaps 3 or 3.5 W/m² instead of 2 W/m², if we keep building in the best spots.

As evidence that I am not deliberately biased against wind, take a look at the data for offshore wind farms.

In my book I assumed a power per unit area of roughly 3 watts per square metre for offshore wind. But the two offshore windfarms in my data have powers per unit area below 2.5 watts per square metre.
There are several other scientists who have used a power per unit area similar to mine when estimating wind resources. For example, Socolow from Princeton uses 2 watts per square metre when discussing his "wedges". On page 234 of my book I cite a study by Elliott et al. (1991) in which windfarms in the best locations in America, covering an area equal to that of California, were estimated to have an average power density of 1.2 W/m².
While my book is technology-neutral, the truth is that personally I am pro-wind! I think wind farms are brilliant, and I'd be very happy be within eye-shot of one almost anywhere in the ordinary countryside.
Please could the commentors call off the dogs?
Thanks! David

More or Less - the Director's Cut

2009-05-08T02:41:00.000-07:00

I was on "More or Less"a couple of weeks ago, and wrote an article for the BBC. One topic mentioned was how much good it does to unplug phone-chargers when they are not in use.

On today's programme (8 May 2009) they are going to read out an indignant listener's letter pointing out that "if everyone unplugs their phone chargers, it adds up to a HUGE saving". More or Less asked me to write a short response, which is going out today. I'm worried that people will get the impression I am against switching anything off. So for the record, I would like to point anyone who's interested to the relevant pages of my book (p114) and Chapter 22 (p155) which should make clear that I do think that it's a good idea to find the big vampires and switch them off!
Here's what I wrote for today's More or Less, in full:
Yes, if sixty million people all make a figleaf gesture that saves half a watt (which is roughly one ten thousandth of their power consumption), then the total power saved is,
sixty million times half a watt
which is 30 megawatts, which sounds like quite a lot. It's one thirtieth of the output of a modern power station, for example. But this "if-everyone" multiplying machine is just a misleading way of making something tiny sound big:
30 megawatts is still just one ten thousandth of Britain's total power consumption.
Multiplying tiny things by sixty million to make them sound big is BAD because it distracts people from thinking about sixty million bigger things that are more deserving of our attention. [Heating sixty million buildings, and driving sixty million cars, for example.]

Hot Air Oscars nomination: biodegradable tat from 'I love planet'

2009-05-03T10:11:00.000-07:00

I went to Edinburgh botanic garden today. The visitors' shops of such places are often nesting places for the monsters that spawn green tat.
Here I found the "biodegradable ballpoint pen". Pick it up and look at it: apart from the reassuring "planet loving" messages screaming out from its barrel, it looks and feels like a completely normal pen. And I'd be happy to bet that all its biodegradable parts are made from fossil fuels.
Is it really 'loving the planet' if you buy this fossil-fuel-plastic pen and chuck it away, rather than buying a (ten times cheaper) normal fossil-fuel-plastic pen and chuck it away?
I nominate this pen for the Hot Air Oscars consumer feel-good tat award.

Renewable planning map for the USA

2009-05-03T06:16:00.000-07:00

One thing I've wanted to do, after the Energy book, is to make an interactive tool that conveys the scale of renewable facilities required to make a difference, and gives the user choices, subject to the "it has to add up" constraint. Here is an NRDC Google map; it's a start - it shows "where renewables have potential" in the USA; but it's not quantitative - it just shows "lowest potential" and "highest potential" on a colour scale, for one renewable at a time. The image above shows the map of Montana for Cellulosic Bioethanol. I suspect the main uses of this map will be (1) wishful thinking [about the 'HUGE' potential of renewables] and (2) NIMBYism [using the argument 'this isn't the best place for it'].
PS - when you drill down into the meaning of the map, the colour scales are given a quantitative meaning, but it's not human friendly and it does not use comparable units. For example the colour code of the Cellulosic map is explained thus:
Each county is color-coded based on total dry tons of cellulosic biomass per year, by county. [12,000; 50,000; 100,000; etc]
If I understand right, they are showing potential per county. That is bizarre. So if there are two identical regions but one happens to be divided into 10 counties and one is a single county, the single-county region will be shown as having big potential and the ten-county region will come out two notches lower.

Hot Air Oscars nomination: Tesco again!

2009-05-01T06:33:00.000-07:00

Philip Fowler has nominated Tesco for the "Every Little Helps" lifetime achievement award, in recognition of their services to consumer awareness through labellling toilet paper with its carbon footprint - 1 gram per sheet, giving a new meaning to the motto "Cut the Crap!"

Four simple actions

2009-04-29T16:20:00.000-07:00

I wrote an article, "We need a plan that adds up", for The Guardian and publicservice.co.uk. For the Grauniad I also created a new graphic which I thought I would show here.

Four simple actions that make significant energy savings, and one that doesn't.
The left-hand column shows five contributors to the average energy consumption of a typical reasonably-affluent Guardian reader. The right-hand column shows the reduced consumption, post-action.
Any comments? Would the figure work better if I put the phone charger in the middle instead of at the bottom of the list?

Man on radio

2009-04-24T15:45:00.000-07:00

BBC Radio 4 has a programme called More or Less, all about numbers. On 24 April 2009 the programme opened with a conversation between me and Tim Harford, talking about energy numbers. Tim likes the book (in fact he likes it so much that he gets its name wrong!) After me, he talks to a lady from the Sustainable Development Commission who graciously dismisses my book for being full of big equations and too technical. Or something. Can anyone understand what she's on about?
If you are quick, you can listen to the podcast.
I also wrote an article for the BBC website, 'Saving the planet by numbers'.

Hot Air Oscars nomination: A Clean Use for Australian Coal

2009-04-23T01:37:00.000-07:00

Australian Minister for Resources and Energy, Martin Ferguson, is hereby nominated for the Hot Air Oscar for highest-impact use of the words 'clean', 'ultra-clean', and 'low emissions'.

"This technology unlocks energy from Australia's significant stranded and uneconomic coal reserves."
"Technologies that convert coal and gas to ultra-clean diesel and jet fuel have the potential to replace Australia's declining oil reserves."
"The Australian Government is encouraging the development of coal-to-liquids in Australia through its election commitment to use the $500 million National Low Emissions Coal Fund to support projects generating minimal carbon emissions which utilise our extensive coal resources."

In a nutshell, they're investing government money in turning uneconomic coal that would otherwise have been left in the ground into CO₂ in the atmosphere. Brilliant! Icebergs all round!

Thanks to Alexander Ac for the nomination.

Man holding bulb

2009-04-21T15:39:00.000-07:00

On youtube, there is a new video, arranged by the University of Cambridge, featuring someone not unrelated to me, holding a lightbulb and talking about energy plans. Hope you enjoy it! It took three days of filming to make it.

[In case the youtube video goes missing, here is the University's 'Cambridge Ideas' page.]

Every little hurts - Hot Air Oscars

2009-04-06T10:28:00.000-07:00

There is
a superb article on Greenwash by Ed Gillespie.

Buy eco-lights, get free air miles.

Wow, Tesco has to be a strong contender for the Hot Air Oscar for best consumer-engagement

Hot Air Oscars nomination: Eco Friendly Mobile Phone Charger

2009-03-31T23:35:00.000-07:00

Thank you to Pierre Joly for nominating The Plug In And Go Green Eco Charger for the Hot Air Oscar for Best Use of the "if-everyone" Multiplying Machine. If you've read Sustainable Energy - without the hot air or my page on phone-chargers left on standby, you'll know how thrilled I am to learn that
"The Eco Charger reduces the amount of energy needed to power a mobile phone more than any other on the market."
Fantastic news. If everyone got one of these, the ad says, the UK "could make a collective saving as a country of £85 million" (assuming, incidentally, an electricity price of 28.5p per kWh... Shurely a bit high?!).
Unfortunately the CarPhone Warehouse didn't have the space in their advertisement to apply the "if-everyone" multiplier to the price tag, but the Hot Air Oscars column is happy to help out: If everyone in the UK bought one of these "Eco Chargers" (at £22.99), it would cost us, as a country, £1.3 billion.

Greenbird wind-powered car - brilliant!

2009-03-29T09:24:00.000-07:00

British engineering breaks wind-powered land-speed record. Wow!

Hot air Oscars nomination: most useless invention

2009-03-28T05:17:00.000-07:00

Nick Cook has nominated the EDF Energy ideal home show, Alex Hort, and the University of Plymouth for a Hot air Oscar for "An ingenious idea that recovers useful energy from a drain pipe". "Rain water descending a down pipe is captured and stored behind an internal 'dam'... Each rush of water turns a small, plastic turbine... providing electricity which is stored in rechargeable batteries."
The raw power of rainwater on a roof of area 40 square metres, rainfall 584 mm per year, with a drainpipe of length 6 metres, is 0.001 kWh per day. This is less than one ten-thousandth of the average British person's electricity consumption. The economic value of the power captured by this contraption is roughly 5 pence per year. The energy cost of making the system and inserting it into a drainpipe must be many times greater than the energy it would ever give back.

Display energy certificates - a missed opportunity to communicate

2009-03-24T14:29:00.000-07:00

UK legislation requires that many large buildings display a certificate, updated every few months, that shows "how efficiently the building is being used".

This mandatory certificate could have been used to communicate information to people, and to engage the building's users in the challenge of improving the building's energy consumption. However, it seems to me that the designers of the certificate have almost completely blown it: the certificate's main features looks fairly colourful, but they convey amazingly close to no information at all.

How much information can be conveyed on a sheet of paper? One of the simplest principles of communication is that the message should depend on something; the message should not be fixed in advance. For example, Lord Nelson, at sea, had a collection of a few dozen flags from which he could select some to run up his mast. Which ones he ran up his mast depended on what message he was intending to communicate. Someone looking at Nelson's ship would not know in advance what the flags would look like.

This communication principle is almost entirely lost from Display energy certificates: the look of the certificate is almost entirely determined and fixed before any building data are collected.

The most prominent feature of the certificate is the "A-to-G" scale, with its green-to-red/brown colour scheme. Almost all the numbers on this scale are fixed; the only adjustable piece is the little arrow that points at "how well this building is being used". This performance is measured in meaningless pseudo-units, with "100" corresponding to "average for buildings of this type". This number can't be compared, from building to building, since two buildings might be of different types, and the certificate doesn't say anything about the type. Nor can an ordinary person work out what the number means, nor what they should do about it, because the number can be computed only by experts using the government-approved software that churns out these certificates. (I've looked on government websites, and have been unable to find any definition of the magic formula for computing the number; I imagine I would have to pay to attend a government-sanctioned course in Display energy certificate cookery.)

The second feature of the certificate is the top-right blue rectangle. Again, this object achieves amazingly little communication. It is meant to show how much CO2 the building's use is emitting. I would like to make a prediction: I predict that, on the first certificates displayed in the year 2009 in all the thousands of buildings across the country, every single certificate will have a blue rectangle of exactly the same height!. I make this prediction because it looks to me as if the government-sanctioned standardized software auto-scales the entire blue rectangle so that it has got a standard size! Therefore the only way to find out the CO2 emissions of the building is to look really closely at the scale of the graph, which shows, in the smallest font conceivable, an absurdly long number, at the top of the vertical axis, partly overlapping the axis. This absurdly long number, I would guess, is the actual CO2 emissions. In my photo I think it shows 26095 tonnes of CO2 per year. If someone ever manages to read this number (please bring a magnifying glass!), will it mean anything to them? Is a typewritten number a good way to convey information? Is it a good idea to show five decimal places of precision? When communicators discuss how to label the axes of a graph, does anyone recommend that the six tics on the graph should be labelled (nothing), (8693), (nothing), (17396), (nothing), and (26095)?

The one interesting fact that is well conveyed by the blue rectangle is the breakdown of CO2 emissions between electricity and heating: the top (light) half of the blue rectangle shows the electricity contribution, and the lower (dark) half shows the heating.

And finally, the third prominent colour element in the display is the "Previous operational rating" graph (bottom right, orange), which shows "how efficiently energy has been used in this building over the last three accounting periods". At present (in early 2009), this colour object conveys no information at all as it shows only a repeat of the energy performance rating displayed on the left-hand side. In due course, maybe it will reveal an interesting trend, but it will depend on the choice of "accounting period". Is the accounting period going to be one year? If so, the comparison of last year with the year before will be meaningful, but is it going to engage users? Imagine if, every day when you entered your building during 2009, the porter informed you what the total energy consumption had been in 2007 and 2008. Would these facts interest you in putting effort into efficiency drives? I fear that a yearly update is too long a timescale for any useful engagement to happen. On the other hand, if the "accounting period" lasts, say three months, then the variation in operational rating from quarter to quarter would be entirely dominated by seasonal effects. My guess is that the certificates will be updated annually, so building-users will become completely blind to the certificate. The opportunity for user engagement is almost entirely lost.

What have we seen so far?

1. the main colourful numbers are in meaningless units. As it says, "the numbers do not represent actual units of energy consumed; they represent comparative energy efficiency. 100 would be typical for this kind of building."
2. the CO2 emissions are displayed in meaningful units, but these numbers are not displayed in a way that an ordinary person can understand.

Does the certificate have any useful information on it? Yes, hidden away in tiny print at the bottom left hand side are interesting numbers - at least to building energy specialists. The "technical information" shows, in a table, the energy use (heating and electrical), expressed in the meaningful units of kWh per square metre per year. And to make this energy use comprehensible, the table also specifies the "typical use" (of buildings "like this", I presume).

What could have been done better? As far as I can tell, the entire piece of paper is really conveying just two numbers:

`this building's heating consumption is: 519 kWh/m2/y';
`this building's electrical consumption is: 249 kWh/m2/y'.

The certificate hides these two numbers in the technical corner, displays some unknown munging of them on to the A-to-G scale, displays their effective carbon-ratio in the blue rectangle, and shows how the total changed compared to earlier years.

How could the certificate be better? Well, it could have been better in two ways:

1. the certificate could display the two numbers that it is meant to communicate more clearly, more accessibly, more meaningfully, and more educationally.
2. the certificate could communicate more than two numbers.

Let me spell out what I mean.

1. the certificate could display the two numbers that it is meant to communicate more clearly, more accessibly, more meaningfully, and more educationally. For example, the energy consumption (per square metre) could be displayed visually on a scale that shows the energy consumptions of a bunch of other real buildings - so as to help people visualize and aspire. Looking at the current A-to-G scale, someone in a "D"-performing building may well ask "does any building like mine ever get an A or even a B?" They don't know if it is at all plausible. If energy consumption were compared with that of benchmark buildings (eg, Whitehall, the Swiss Re tower, Freda's flower shop, Cambridge University Library, BedZed), then people would see what is possible, and could get a message such as "my building is as bad as Whitehall!" or "we're using 20 times as much as BedZed." Given real comparative data, people could aspire to meaningful goals.
2. the certificate could communicate more than two numbers. For example, there could be a duty to display and compare energy consumption every month or every week (for at least some number of consecutive weeks per year). Then the regularly-updated certificate could engage building-users in the challenge of energy-saving. If someone tries an energy-saving action, they need to get feedback within a week to tell them whether it made a difference. Without rapid feedback, no-one will be interested in energy saving ideas.

PS - To see the whole certificate in one image, follow this link

Uncontrollable burning coal-waste-heap

2009-03-11T16:51:00.000-07:00

People often emphasize the role of uncontrolled accidental burning of fossil fuels in backward parts of the world.
I grew up in a part of the developing world called the Potteries, near the middle of England. The Potteries were rich in clay and coal, and one hill near Keele village was stuffed with little coal mines when I was a child. There were rich thick seams very close to the surface. These photos and google satellite maps show what's left there now: a great pile of rubble that is perpetually on fire. It looks rather like a Hollywood movie's improbable view of medieval England, in which every slope somehow has smoke scudding across it.

Eco super hero

2009-02-24T15:37:00.000-08:00

Great to see that colleges are training people to be eco heroes, installing HEAT PUMPS and SOLAR THERMAL SYSTEMS!! Brilliant news.

Designers with a conscience

2009-02-20T02:09:00.000-08:00

Graphic designers for good - looks like a useful community of people to tap into! They don't just want to promote useless consumerist tat.

Even more wind power per unit area

2009-02-18T16:49:00.000-08:00

This is my third post giving factual data about the power per unit land area of wind farms in Britain. My first post described a farm near the coast made of small machines (27m diameter); the power per unit area was 1.4 W/m². The second post cherry-picked the best windfarm in Britain (located in Shetland); the power per unit area was 6.5 W/m². The turbines there have diameter about 50m. Now returning from mid-ocean, let's ask "what do really big land-based turbines deliver?" I picked the Glass Moor windfarm, which has eight 2 MW machines, each with a diameter 82m. (It's the biggest windfarm close to Cambridge; no special cherry-picking, here.) Looking at the OS map, I judged the area occupied by the windfarm to be 2 km². Based on one year's data, the average output of this windfarm (per unit land area) is 2.2 W/m².
These data support the view that 2 W/m² is a good ballpark figure for the power per unit area of a modern windfarm in England.

Climate-change inactivism

2009-02-15T05:16:00.000-08:00

I enjoyed reading John Mashey on how science works, and how to critically read scientific claims such as those made by climate-change inactivists. From there, I found my way to his equally interesting analysis of Bjorn Lomborg's motivations. I actually rather like Bjorn Lomborg and don't think he's the antichrist that many make him out to be; but it is interesting to read John Mashey's analysis of the political effect of Bjorn Lomborg's arguments. In a nutshell, Lomborg's recent writings have said "yes, global warming (X) is a priority, but not as high a priority as 'A' and 'B'", where John Mashey reckons A (Eg, give lots of money to the developing world to fix things there) has been chosen not because Lomborg really wants to devote effort to A, but rather because he knows these sort of aid donations won't happen, so putting them top of a list of priorities is a good way of persuading people not to do lower things in the list (X). The space in the list between A and X is padded out with other items ("B") (eg, open up free trade more) that the neo-cons would be happy to see happen. Interesting analysis.
Myself, I had a different take on Lomborg, which is that he genuinely does care, and wants us to choose numerate policies that work; and that he comes to different conclusions from some of us simply because he tacitly chose a different objective from what we might have chosen. Specifically, the objective in his recent books seems to be something like "human economic welfare between now and the year 2100". I'd love to sit down with Lomborg and discuss what he thinks the optimal investments would be if the objective were changed to "planet still functioning well at supporting human life in the years 2200, 2500, and 3000".
I've tried to converse with Lomborg but sadly I think he's too busy being famous now.

Hot Air Oscars: Recyclemania and Eastern Washington University dining services

2009-02-11T13:51:00.000-08:00

I'm happy to announce the launch of the first annual "Hot Air Oscars".
These awards go to the person or organization who (in the judgment of the panel) best exemplify the modern-day survival skills of greenwash and twaddle-emission. There will be awards for "most misleading advertising", for "best use of magic playing fields", for "best doublespeak", for "most creative use of the word 'zero'", for "best bogus comparison", for "best speaking with many faces", for "best supporting liar", for "best inflated difference", and for "best conparison".
Nominations may be sent to David MacKay. Shortlisted achievements will be featured on this blog over the next month or two. The winners of the Hot Air Oscars will be announced in mid 2009.

Opening nominations...
The first nomination in the "best green spin" category is the fine attempt by David McKay [no relation], director of dining services at Eastern Washington University (EWU), and Paul Kyle, associate director of dining services, to put a positive spin on their decision to use disposable Styrofoam plates and bowls in the cafeteria. "Our goal is to lessen the amount of BODs [organic pollutants in water] by washing fewer dishes," said Kyle; "The use of Styrofoam plates and bowls is an excellent energy source for the waste-to-energy plant," said McKay.
or to put it another way, Styrofoam plates are great because you can just throw them away and burn them. They claim that this initiative somehow ties in with a local initiative called Recyclemania.

I am sure the environment is thanking them for their efforts, but not everyone is so supportive. Laci Hubbard, president of the Eastern Environmental Club, said that while the group is pleased that Dining Services has been supportive of ... Recyclemania, they are "concerned about the move to use additional Styrofoam products and the logic of their subsequent explanation for why Styrofoam is a better choice for the environment."

Please keep the nominations rolling in. The judges will be happy to consider new categories for the Hot Air Oscars.

More windfarm power per unit area

2009-02-11T12:15:00.000-08:00

Executive summary:
The windfarm with the highest load factor in the British Isles has a power per unit area of 6.5 W per square metre.

Background:
Commentors on my previous article on
the power per unit area of windfarms queried whether any cherry-picking might have happened
in the selection of Blood Hill windfarm; it was also suggested that we should work out the numbers for Burradale, the famous windfarm in Shetland with the highest load factor in Britain. The answer to the first query is "no, not at all" - Blood Hill was selected at random, and as I said, I would encourage anyone who can be bothered to look up the data for other windfarms to do so and add the results to the "withouthotair" wiki.
And now, to satisfy the request for cherry-picked facts about wind in the UK, I am happy to present...

The data: Burradale has five wind turbines: three in "phase 1" and two in "phase 2". Their capacities are 660 kW and 850 kW respectively, and their average outputs over the last few years have been 357 kW and 446 kW respectively. (That corresponds to load factors of 52% and 54%.) I judged the "area occupied" by the five turbines to be 0.3 square kilometres. The average power per unit area of this windfarm is 6.5 W per square metre.

This number can be compared with my assumed figure of 2 W per square metre for typical onshore windfarms in the UK.

So, a cracking good place for wind, Shetland! What does it need? Obviously what this place really needs is a campaign group opposed to expanding wind farms in Shetland. And The Good Lord hath provided "Sustainable Shetland".

Power per unit land area of windfarms

2009-01-31T08:57:00.000-08:00

As I've said in SEWTHA (the book), the average power per unit land area of a typical well-located onshore windfarm in Britain is about 2 watts per square metre. (Or 2 MW per square km.) This number is my estimate of the best that can be done in Britain, and, as I explained in the appendix, the theoretical power per unit land area doesn't depend very much on the size of the turbines used, because bigger turbines are spaced further apart.

I'm always keen to check my numbers and update them if necessary. Today the the New Scientist interview with James Lovelock prompted me to write a blog article giving explicit data from a real windfarm. James Lovelock says "to spoil all the decent countryside in the UK with wind farms is driving me mad. It's absolutely unnecessary, and it takes 2500 square kilometres to produce a gigawatt - that's an awful lot of countryside." That's a power per unit area of 0.4 W/m², which is 5 times smaller than my 'best possible' 2 W/m² estimate.

Let's look at some data. I picked a random windfarm in Britain with ten 27m-diameter turbines: Blood Hill windfarm. The helpful REF website gives exact energy-generation statistics for several years. The collage at the top of this page shows the data, and a map of the site, which is very close to the sea in Norfolk. What's the area of this site? The blue grid lines are 1km squares. I'd say the ten turbines 'occupy' about 0.3 km² (including an appropriate strip of land around the turbines, where similar size turbines could not be placed). The average output of the ten turbines is 420 kW. So that is a power per unit area of 1.4 W/m².

If anyone would like to repeat this calculation for real data from other windfarms around Britain or the world, we could collate the answers in the open-source wiki for Sustainable Energy - without the hot air.

Google searches, energy cost, carbon footprint, and cups of tea

2009-01-12T07:21:00.000-08:00

A friend asked me to confirm or deny the assertion (Harvard/BBC) that two Google searches on a desktop computer produces 14g of CO2, which is the roughly the equivalent of boiling an electric kettle.

``US physicist Alex Wissner-Gross claims that a typical Google search on a desktop computer produces about 7g CO2.
``However, these figures were disputed by Google, who say a typical search produced only 0.2g of carbon dioxide.''

My own rough back of envelope guess came out in between Wissner-Gross's assertion and Google's...

Here's how I worked it out:

according to a google search(!), google has about 700,000 servers.
let's guesstimate the power to run a server and all its plumbing: 250 W.
google received 90 million searches per day in 2006
and 1200 million per day in 2007...
Hmm, this growth rate is big enough that it is going to be hard to get a trustworthy answer!
Well, let's multiply 700,000 servers * 0.250 kW * 24 hours per day / 1200 M searches per day -
that is 0.0035 kWh per search; 0.007 kWh for a pair of searches; and 3.5g of CO₂ for a pair of searches. (Assuming that electricity has a footprint of 500 g per kWh.) [In fact I think I heard that google has lots of servers in Iceland, where the electricity footprint is much smaller.] Meanwhile, boiling a 250 ml cup of water uses about 0.028 kWh. So my estimate is that the energy cost of two google searches (measured at the googleplex alone) is about one quarter of the energy cost of boiling a cup.

This calculation has not included the energy cost of running your own desktop computer, wireless, and modem for the duration of the search too; nor the cost of running the internet twixt you and google. If it takes you one minute of computer time to do the search, and if your computer and peripherals use 120 W, then the cost of your computer's power in that duration is 0.120 kW * (1/60) hour, which is an extra 0.002 kWh.
Here's the bottom line from my rough guesses: the total energy cost of the pair of searches seems to be about 0.01 kWh. That's exactly the same as the energy used by leaving a phone charger plugged in for one day. Which is also the same as the energy used by driving an average car for one second.

Would electric freight vehicles be possible?

2009-01-03T10:03:00.000-08:00

In Sustainable Energy - without the hot air, one of my main conclusions is "electrify everything" - in particular, I recommend electric vehicles. At a recent talk, someone in the audience said, yes, maybe electric cars are now viable. But surely you couldn't electrify freight? Leaving aside two possible answers (namely 1: for local freight deliveries, electric trucks are already genuinely in use, and are manufactured by a couple of companies in the UK; 2: we could make electric freight like eletric trolley buses, using overhead lines), I thought it would be interesting to investigate, using the same model I used for cars in my book, the possibility of making long-distance freight vehicles with on-board batteries.
The model assumes that energy goes into air resistance, into rolling resistance, and into brakes. The model includes regenerative brakes (assumed to be 50% efficient, round-trip), and includes energy inefficiency in the energy-conversion chains (from grid to battery and from battery to wheels). The frontal area is assumed to be 8.6 m² and the freight carried is 26 tons. The other main assumptions are the distance between stops (500m? 5000m?) and the typical speed (50km/h? 100km/h?).

The figures above and below show the theoretical energy consumption (in kWh per ton-km) for two different batteries' energy densities (corresponding to lead acid and lithium), compared with a fossil fuel truck with the same frontal area and load, versus the range (ie the distance between refuelling stops). The top figure is for the case of 500 m distance twixt stops and 50 km/h speed. The bottom figure (just above) is for the case of 5000 m twixt stops and 100 km/h speed.
The bigger the battery, the bigger the range and the bigger the energy consumption. The main conclusion of these figures is that, on energy grounds, trucks with big batteries are viable. They are superior in energy consumption to the fossil fuel truck. (The point at the top, by the way, is the fossil fuel truck benchmark from the book, which is obtained from government statistics; the lower point is the theoretical performance of a fossil fuel truck according to the model. The latter is presumably lower because the former includes a load of empty-running journeys.)
Of course many other factors need to be borne in mind - could a truck stop provide a 120-kW outlet for charging each truck parked at the truck stop, for example? And what is the capital cost of the batteries? And could they be recycled?
But I find it interesting that in principle, long-distance electric trucks would be more energy-efficient than fossil-fuel trucks. As usual, I have declared one unit of grid electricity to have the same value as one unit of chemical energy. Yes, yes, with today's electricity mix in Britain, blah blah blah, inefficiencies in conversion, ... a factor of 2.4 or some such... But as usual I am focussing attention on the future energy system we should be building, not the details of today's obsolete fossil-fuel electricity system. We want to electrify transport in order to get the whole energy system off fossil fuels as much as possible.

The FCX Clarity from Honda

2008-12-20T06:33:00.000-08:00

On this week's Top Gear, James May called the FCX Clarity "the most important car for 100 years".
[Photo courtesy of automobiles.honda.com.] It runs on hydrogen, which "will never run out", because it is "the most abundant element in the universe". And the only emissions are water.
What twaddle!
The programme took the time to point out that the electricity to power a Tesla electric car in Britain is produced at a fossil fuel power station. Why didn't they also discuss where the hydrogen comes from?
Top Gear loves to quantify accelerations, lap times, car prices, top speeds - why couldn't they quantify the energy requirements to run "the car of the future", the FCX Clarity? And compare it with the Tesla?
Here's the answers, according to chapter 20 of Sustainable Energy - without the hot air.

The energy consumption of the FCX Clarity is 69 kWh per 100 km. (Very similar to the consumption of an ordinary fossil fuel car.) That's assuming the hydrogen is produced in the standard way, using lots of methane and a bit of electricity, and counting one unit of chemical energy as having the same energy content as one unit of electricity. Meanwhile, the energy consumption of the Tesla (according to its manufacturers) is 15 kWh per 100 km. (Of electrical energy.) Even if we penalize electricity, saying "every 1 kWh of electricity costs 2.5 kWh of fossil fuels", the Tesla is still much better than the fuel-cell car, and better than the average fossil fuel car. (And in the future, we won't be getting electricity from fossil fuels, hopefully!)
So the hydrogen car is NOT a "solution" to our problem, if our fundamental problem is an energy problem.

Why on-site renewables don't add up

2008-12-06T03:09:00.000-08:00

Straight up, I want to say I love renewables, and I believe that we should have a massive increase in renewables as part of making a sustainable energy plan that adds up (as explained in my book Sustainable Energy - without the hot air, now available on paper).
This is an article about on-site renewables. Imagine a developer is making a new urban development. Offices or homes, perhaps. A three-floor building. Under some planning regulations, new buildings must get some fraction of their energy consumption from on-site renewables. Now, these regulations have some undeniable benefits: if it is expensive to install on-site renewables, the developer may modify the building so as to reduce its energy consumption, thus making it less costly to reach the required renewable fraction. Having local renewable energy production may also increase awareness about energy consumption among the building's users. And some local renewables are no-brainers - making hot water using solar panels, for example, makes complete sense, providing roughly half of the hot water consumption of an average home.
But here is the problem:

200 kWh per year per square metre = 23 W per square metre

On the left, 200 kWh per year per square metre is the typical total energy consumption of many homes and offices, expressed as energy per year per square metre of floor area. In terms of energy rating bands, 200 kWh/y/m² is the boundary between bands F and G. Many government buildings use twice as much as this. (The Home Office uses 400 kWh/y/m², for example.) The Passivhaus standard, at 120 kWh/y/m², is not much better than this 200 kWh/y/m² benchmark.
On the right, I've converted this quantity into watts per square metre, which are the unit in which I prefer to express renewable power production. Sadly, most renewables have powers per unit land area that are substantially less than 23 W per square metre. Wind farms generate 2 W/m². Energy crops generate 0.5 W/m². Solar photovoltaic panels generate 20 W/m². And remember, we're imagining a three-floor building. So the power required per unit land area occupied by the building is not 23, but 3x23 = 69 W/m².
On-site renewables are an interesting gesture, but if we are serious about renewables making a big contribution, they have to be big - they must occupy a land area much bigger than the land occupied by the buildings we are powering. If you want to completely power a three-floor 200 kWh/y/m² building from energy crops and wood, for example, then the land area required for the energy crops and wood must be roughly 140 times as big as the land footprint of the building.
The response of an angry green campaigner to what I have just written can be predicted: "But we could make the buildings far more efficient!" Could we? I'd love us to build more-efficient buildings, but show me data. Not wishful thinking, but NUMBERS. The Elizabeth Fry building at UEA is often held up as an example of a state-of-the-art eco-friendly building. And here are the numbers for that building (from page 299 of my book). It consumes 96 kWh/y/m², which is 11 W/m², which is only about 50% better than the Energy-Rating-Band-F/G benchmark from which I started.
The bottom line: if you want to completely power a typical building, or even an amazing eco-building, from renewables, most of those renewables have to be offsite. There isn't room on-site! And it's probably a better use of resources to accept this fact up front, rather than force developers to squeeze uneconomic figleafs (such as micro-turbines) into their developments. We should modify the planning regulations for new buildings so that developers are still required to build renewables, but are encouraged to build new renewable capacity off-site.

Petrol, diesel, miles per gallon, litres per 100 km, energy, and emissions

2008-11-23T05:59:00.000-08:00

Too many units! Too many things to measure! In Europe they talk about "the one litre car" (using 1 litre of fuel per 100 km). In Britain, drivers of the Prius are happy to do "more than 50 miles per gallon". In the USA, gallons are different. Then there's emissions (does it emit less than 100 grams of CO₂ per km?) and finally there's energy measures (for example, the average British car consumes 80 kWh per 100 km).

And, while we're dealing with all these different units, the most annoying detail of all is that petrol is different from diesel. Diesel has bigger energy per litre (roughly 10% more), and it has bigger carbon emissions per litre too.

I've put together a graph that makes it possible to compare and convert some of these measures of vehicle performance.

Some memorable anchors on this diagram:

A 90 mpg petrol vehicle is roughly equivalent (in energy and emissions) to a 100 mpg diesel car. Both use an energy of about 30 kWh per 100 km and have emissions of about 75 g per km. People have sometimes lampooned the Prius for consuming more fuel than a BMW. If the Prius is using petrol and the BMW is using diesel, then it's not fair to compare the numbers of litres used.
A 'one litre car' delivers 282 mpg, and uses about 10 kWh per 100 km. This is the energy consumption, incidentally, of quite a few prototype electric cars (measured at the socket).
My 'average UK car today' uses 80 kWh per 100km and emits 200 g per km. Europeans would call it an 8-litre car.

For more about energy consumption of eletric vehicles and hydrogen vehicles, see Sustainable Energy - without the hot air.
Small print: 'mpg' means miles per imperial gallon. 'g' means grams of carbon dioxide.
Energy contents (high heat values) and emissions were assumed to be:
Petrol: 34.7 MJ per litre; 2344 g per litre.
Diesel: 37.9 MJ per litre; 2682 g per litre.

Good article on 'green electricity'.

2008-10-24T07:18:00.000-07:00

I always lampoon 'green electricity tariffs' in my lectures. The Grauniad published a good article on them yesterday. Key points: the electricity companies sell some MWh of 'green' electricity multiple times; and the big power generation companies are falling way below the fraction of green electricity that they are meant to produce under the subsidy scheme.

How to boil water

2008-10-19T12:59:00.000-07:00

A friend told me he'd been fighting with his kitchen-cohabitants over the question of whether to simply use the gas to make hot water for pasta, or whether to use the kettle, then put it in the pot.
To answer this question quantitatively, I did some experiments and I've written a new webpage, How much is inside HOT WATER? The page assumes that the motivation is to save energy. The conclusions apply to Britain today and to similar countries.

My conclusion is that using the gas hob is slightly better in energy terms than using the kettle; but my recommended behaviour depends on the time of year. In the winter, if you would like to have more heat in your kitchen, then using the gas hob alone is definitely best; in the heat of summer, using the kettle may be preferable.

Disclaimers, small print...
If your motivation is to save money then the answer will depend on your fuel prices. If your motivation is to cook the pasta as fast as possible then you should use neither method alone - you should use both the kettle and the hob, with roughly half in each.

Lights on cars in the daylight

2008-09-26T11:08:00.000-07:00

According to the Dail Mail, crazy European legislation forcing car drivers to keep headlights on ALL day could inflate fuel costs by up to £160 a year.

What are the numbers? Well, this is one that I worked out earlier. It's in chapter 9 of Sustainable Energy - without the hot air, on page 58. Let's say the four bulbs for the running lights on a car use about 100 W. Allowing for the engine's and generator's inefficiencies, this 100 W of bulb power requires a petrol power of 730 W. For comparison, the petrol consumption of an average car running along at 50 km/h and consuming one litre per 12km is 42000 W. So having the lights on while driving requires 2% extra power.

If you drive 50km per day and fuel costs £1.20 per litre then you spend £5 per day on fuel. Putting the lights on is going to increase your costs by 2%, which is 10p per day. That's £37 pounds per year, for a typical driver. Obviously the answers come out differently if we change the vehicle to a Hummer, or if we replace the incandescent bulbs by modern LEDs.

I hope this helps!

The book's finished!

2008-09-25T17:42:00.000-07:00

I'm happy to announce that Sustainable Energy - without the hot air is finished.
It's got a publisher, a cover design, and a publication date of December 1st 2008.
All that remains is some frantic last minute editing and correcting; then an 8-week wait.
The book will remain free on my website.

Performance data for a GWiz in London

2008-07-25T05:45:00.000-07:00

This article is by Kele Baker and David MacKay, based on data collected by Kele

The performance of the G-Wiz varies with driving conditions and the weather. The G-Wiz can be driven on 'high' or 'low' power. The lights may be on or off. And the efficiency of the battery appears to depend on the temperature. The graph shows data for 19 charging events: the distance travelled in miles is on the horizontal axis and the energy required from the grid to recharge the battery (measured at the socket with a Maplin meter) is on the vertical axis.

The best performance was 16 kWh per 100 km. The worst was 33 kWh per 100 km. The average was 21 kWh per 100 km. This number is roughly four times better than the energy consumption of an average petrol car doing 33 miles per gallon, which uses 80 kWh per 100 km. In money terms, the electricity cost of the G-Wiz is 2.1 pence per km (assuming 10 p per kWh).

Mysterious cheap electricity generated in Nevada

2008-07-22T11:54:00.000-07:00

There is a strange violation of economics going on on the Nellis Solar Power Plant wikipedia page. It asserts that the US air force are paying 2.2 c per kWh for electricity from a solar PV farm that happens to be on their land. This sounds far too cheap. The article says the '14MW' farm cost $100M to build (that's 7 dollars per watt, peak) and will generate 25M kWh per year. That means it will generate an income of $0.55M per year for the owners of the farm (who paid $100M, remember). That corresponds to a pay-back time of 180 years. So what's going on? Is it a strange Nevada phenomenon? Did aliens subsidise the farm? Or did wikipedia get the numbers wrong?

I DO advocate switching off electrical gadgets on standby

2008-06-23T15:29:00.000-07:00

Well, well, it's been an interesting few days... Since The Register posted an article about my draft book, I've received a flood of emails, and been shocked to observe the cacophony of people on blogs and bulletin boards all debating 'what the Professor said', plopping me in one camp or another of their running battles.

I'd like to make one suggestion to everyone: if you want to discuss what I said in the book, please read the book!.

Some readers seem to think that whatever the journalist wrote, I said. For example his introduction said that most people 'have no need to worry about the energy they use to power their electronics; it’s insignificant compared to the other things'. That was the journalist, not me! This attitude to standby power has provoked the mob to get out their flame-throwers, saying 'MacKay should know that 8% of all domestic electricity goes to power junk on standby!' Sigh!

For the record, here is my domestic electricity consumption for the last few years.
I started paying attention to my electricity consumption in 2007. I started switching off all my stereos, answering machines, cable modem, wireless, and so forth, in mid-2007. I am happy to confirm that switching off these vampires has reduced my domestic electricity consumption from roughly 4 kWh/d to below 2 kWh/d. This is an energy saving well worth making; I encourage everyone to bye-bye their standby, and read their meters to see the difference it makes.

The last thing we should talk about

2008-06-02T02:01:00.000-07:00

Wallace Broecker has been promoting the idea that `artificial trees are the way to solve global warming'. Pushed for details, he says that `brilliant physicist Klaus Lackner has invented a method to capture CO2 from thin air, and it doesn't require very much energy'. Broecker imagines that the world will carry on burning fossil fuels at much the same rate as it does now, and 60 million CO2-scrubbers (each the size of an up-ended shipping container) will vacuum up the CO2.

I think it's a very good idea to discuss capturing CO2 from thin air, but I feel there is a problem with the way this carbon scrubbing technology is being discussed. The problem is energy: how much energy does Lackner's CO2-capture method require. `Not very much'? Come on, we need numbers, not adjectives.

Here are some of the numbers required for a coherent conversation about carbon capture. Grabbing CO2 from thin air and concentrating it into liquid CO2 requires energy. The laws of physics say that the energy required must be at least 0.24 kWh per kg of CO2. What does Lackner's process require? In June 2007 Lackner told me that his lab was achieving 1.3 kWh per kg. Let's imagine that further improvements could get the energy cost down to 0.7 kWh per kg of CO2.

Now, let's assume that we wish to neutralize a typical European's CO2 output of 11 tonnes per year, which is 30 kg per day per person. The energy required, assuming an exchange rate of 0.7 kWh per kg of CO2, is 21 kWh per person per day. For comparison, British electricity consumption is roughly 17 kWh per person per day.

So as a ballpark figure, the Broecker/Lackner plan requires an amount of energy equal to current electricity production.

When I call carbon capture from thin air `the last thing we should talk about', I don't mean that we shouldn't talk about it. I definitely think we should talk about it, in detail, to help drive us towards more radical action now, to reduce the need to create these mega-vacuum-cleaners.

P.S. What about trees?. Trees are carbon capturing systems; they suck CO2 out of thin air, and they don't violate any laws of physics. They capture carbon using energy obtained from sunlight. The fossil fuels that we burn were originally created by this process. So, the suggestion is, how about trying to do the opposite of fossil fuel burning? How about creating wood and burying it in a hole in the ground, while, next door, humanity continues digging up fossil wood and setting fire to it?
From the minutes of the Select Committee on Science and Technology, the best plants in Europe capture carbon at a rate of roughly 10 tonnes of dry wood per hectare per year. Or in equivalent CO2 terms, that's about 15 tonnes of CO2 captured per hectare per year.
So the area of forest per person required to fix a European output of 11 tonnes of CO2 per year is 7500 square metres per person. (And then you'd have to find somewhere to permanently store 7.5 tons of wood per year!) Taking Britain as an example European country, this required area, 7500 square metres per person, is twice the area of Britain.

Cost-effective ways to reduce your carbon footprint

2008-03-21T15:49:00.000-07:00

I'd like to highlight Sandy Polak's
page on how to be green. It is the best page I've read on this topic. The main thing I would have amplified more than Sandyis heat pumps: I bought a 'green' condensing boiler a few years ago, and now regret having done so - I wish I had looked into air-source heat pumps. Condensing boilers are not green: they use fossil fuels! I reckon that, even if electricity is produced from gas-fired power stations, air-source heat pumps are a good thing, environment-wise; and if and when the grid is decarbonised, heat pumps will get ever greener. Heat pumps have to be the future for domestic heating without carbon.

Eco bollocks awards

2008-03-09T13:59:00.000-07:00

An emailer pointed me to a great blog that features well-written explanations of the authors' occasional Eco bollocks awards. Two model recipients are:
Ken Livingstone, whose claim that London will cut carbon by 60% is given a thorough inspection, and the Windsave WS1000 wind turbine. "Come on, it’s time to admit that the roof-mounted wind turbine industry is a complete fiasco. Good money is being thrown at an invention that doesn’t work. This is the Sinclair C5 of the Noughties."

Mark Brinkley's writing style in this blog is eloquent and fun -- "The world has gone mad. This seems like some insane game about seeing who has got the greenest willy."

Stuff dominates!

2008-02-02T05:06:00.000-08:00

I used to summarise British energy consumption by saying "transport, heating, electricity".
However I just read Too Good To Be True? The UK's Climate Change Record,
(pdf) by Dieter Helm, Robin Smale and Jonathan Phillips, who estimate (based on the value of British imports from other countries, and those countries' carbon intensities) that the net carbon footprint of British imports and exports is 10 tonnes of CO2e per person! - this doubles the British carbon footprint at a stroke and implies that our energy consumption is not dominated by transport, heating, and electricity after all. Stuff is king!

How much hydro does it take to "power Glasgow"?

2008-01-07T07:32:00.000-08:00

Whenever a renewable power facility is described they always say how many 'homes' it will power. Today's news says The 100MW Glendoe Hydro Scheme will be able to power around 250,000 homes – equivalent to a city the size of Glasgow.

I think this 'homes' description is really misleading, because I bet people confuse 'powering all the homes in Glasgow' with 'powering all Glasgow's electricity' or even 'powering all Glasgow's energy'.

Let's do a simple calculation.

The average expected power from Glendoe is 180 GWh per year [source]. Now
if we take 180 GWh per year and share it between a Glasgow of people
(616,000 people), we get 0.8 kWh/d per person.

OK; what is the average electricity consumption per person (including all forms of electricity, not just domestic)? Answer: 16 kWh/d per person. So Glendoe actually provides 5% of the electricity consumption of Glasgow.

So if people get the impression from the press releases that Glendoe will power Glasgow, they have been misled by a factor of twenty!

This is a bigger factor than the normal factor by which people are usually misled. The statement
that Glendoe (180 GWh/y) would power 250,000 homes implies that each 'home' uses just 720 kWh per year. But the normal assumption in press releases about wind or tide is to assume the average home uses 4000 kWh/y or 4700 kWh/y. What's going on? The ratio between 720 kWh and 4000 kWh (18%) is suspiciously similar to the ratio between the average power production of Glendoe (180 GWh/y) and its capacity (100 MW is equivalent to 877 GWh/y). Methinks that someone at Scottish and Southern must have screwed up (or deliberately misled the public) by pretending that Glendoe will produce 100MW 100% of the the time, whereas in fact it will have an average load factor of 20%.

Carbon Carousel Fraud

2007-12-27T12:39:00.001-08:00

Letter to the editor
The Independent Sent 27 December 2007

Sir,

the article 'My carbon-free year' (Independent Thursday 27 December 2007) claims that Donnachadh McCarthy's home was `carbon-negative for energy' during 2007. This would be great if it were true, but the claimed carbon footprint of -141 kg was obtained only by using a carbon carousel fraud.

The home sometimes exported and sometimes imported green electricity. For every kWh of electricity exported, the net footprint was credited with -430g of CO2. Fair enough. But when the home imported a kWh of electricity, the effect on the footprint was declared to be zero. This is a fraud, since under this accounting system a building that imports 1 kWh on Monday and exports 1 kWh on Tuesday (and thus makes no net contribution) would be judged to have removed 430g of CO2 from the atmosphere! When this error is corrected, we find that Donnachadh McCarthy's impressive home is not carbon negative. It has a CO2 footprint of +24 kg.

It is a terrible struggle to make a British home carbon neutral!

yours
David MacKay

PS
Here are the details of the correct spreadsheet
``How the eco-savings add up''

	CONSUMED	CO2 footprint
Gas usage	609 kWh	116 kg
NET export of green electricity (598-384)	114 kWh	-92 kg
Solar electricity produced and used on-site	420 kWh	zero
(Other items in the table all as before, zero.)
Net footprint		+24 kg

PPS - They didn't publish my letter.

Life-cycle analysis database

2007-10-30T17:05:00.000-07:00

Yippee! I've been trying to find a free database of LCA information (to answer questions like 'what's the embodied energy or embedded energy of a fluorescent light bulb?') and now I think I have found one - http://lca.jrc.ec.europa.eu/lcainfohub/introduction.vm

Update...

Sadly the EU database didn't seem very user friendly. I've now found the
The University of Bath database
which looks small but useful.

Climate change in our lifetime

2007-10-30T16:21:00.000-07:00

My first blog. (I've been writing webpages for ages, but I thought a blog might be useful for my soon to be finished book.)

1998 was a record hot year (the hottest in the last few decades). Today I heard in a talk by Vicky Pope that the climate models of the Hadley Centre predict that from 2010 onwards, every year has a 50% chance of being hotter than 1998.

Vicky Pope also showed a graph by Eleanor Burke showing predicted droughts. The graph showed the percentage of the world predicted to have "severe drought". In the past this percentage has bobbled around 2 or 3%. By 2060 it was projected that the percentage would be up to 20%.

I hadn't seen climate change expressed by climate scientists in such strikingly 'soon' terms.