I've been unfair on Hydrogen

In Sustainable Energy - without the hot air I spent a couple of pages discussing hydrogen transportation, under the title "Hydrogen cars – blimp your ride". While I still think that some people have been overhyping hydrogen - even Nature magazine, who praised Governor Arnold for filling up a hydrogen-powered Hummer - some of the criticisms I wrote were incorrect and I wish to correct them.

On page 131 I wrote: ... hydrogen gradually leaks out of any practical container. If you park your hydrogen car at the railway station with a full tank and come back a week later, you should expect to find most of the hydrogen has gone. Both of these statements are incorrect.

First, while hydrogen is a very leaky little molecule, it is possible to make practical containers that contain compressed hydrogen gas for long durations. It's just necessary to have sufficient thickness of the right type of material; this material may be somewhat heavy, but practical solutions exist. The technical term used in the hydrogen community for this topic is "permeation", and it's especially discussed when ensuring that hydrogen vehicles will be safe when left in garages. Hydrogen containers are currently classed in four types, and the metallic containers and containers with metallic liners (Types 1, 2, and 3) have negligible permeation rate. However, hydrogen permeation is an issue for containers with non-metallic (polymer) liners (Type 4) which readily allow the permeation of hydrogen. [Source: P. Adams et al]

Second, when discussing the hydrogen vehicle that is left for 7 days, I incorrectly tarred all hydrogen vehicles with a hydrogen-loss brush that applies only to vehicles that store liquified hydrogen at cryogenic temperatures. There are in fact three types of hydrogen storage: Compressed gas (typically at 350 or 700 bar); Cryogenic (typically at less than 10 bar and at extremely low temperature) and Cryo-compressed (at low temperature and at pressures up to about 350 bar). The hydrogen community discuss the "loss-free dormancy time" and the "mean autonomy time" of a system, which are respectively the time after which the system starts to lose hydrogen, and the time after which the car has lost so much hydrogen it really needs refilling. In the US Department of Energy's hydrogen plans, the targets are for a loss-free dormancy time of 5 days and a mean autonomy time of 30 days. Cryogenic liquid-hydrogen systems (such as the one in the BMW Hydrogen 7, which I featured in my book) do not currently achieve either of these targets. (And the reason is not that the hydrogen is permeating out, it's that heat is permeating in, at a rate of 1 watt or so, which gradually boils the hydrogen; the boiled hydrogen is vented to keep the remaining liquid cold.) However, compressed-gas systems at 700 bar can achieve both of these targets, so what I wrote was unfair on hydrogen vehicles. [Source: EERE 2006 Cryo-Compressed Hydrogen Storage for Vehicular Applications]

I apologise to the hydrogen community for these errors.

I will add a correction to the errata imminently.

L'energie durable - pas que du vent!

On 13th December 2012, I helped launch the French translation of Sustainable Energy - without the hot air by giving a talk in Paris, hosted by the Ecole Normale Superieure and the kind volunteer translators, AMIDES. The book was featured today by Le Figaro: Le Professeur MacKay réduit «les émissions d'âneries» .
Just like the original English book, the French translation is available free on-line, and it can be bought at a reasonable price from your favourite retailers.

• amazon uk,
• amazon.fr,
• fnac.

Personal energy calculator online

Christian Gebbe has made a nice Personal Energy Estimator based on Sustainable Energy - without the hot air. All the key numbers are adjustable, so you can override the default assumptions. It's nicely done, and I am sure Christian will welcome your feedback.

Sun spots and temperature

I love data!
Here is an animation showing the evolution of global temperature and the number of sunspots over the last 129 years.

And in case it doesn't display right, here's the final frame of the animation:
And in case it isn't obvious what I think these data show, the message I get from them is that there is no obvious or strong association at all between sunspot numbers and global temperatures.
(Thanks to Iain Murray for free-software help.)

TEDx talk: People, Power, Area

- how the laws of Physics constrain our sustainable energy options
TEDx Warwick 2012 (18 minutes). [Original slides are also available here]

Version 3 of the 2050 Pathways Calculator

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!

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

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

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

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

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"

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

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!

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

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)

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

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

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

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

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

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!