tag:blogger.com,1999:blog-61569403501591009532024-02-18T23:01:44.727-08:00Sustainable Energy - without the hot airDavid MacKay FRShttp://www.blogger.com/profile/08023079754784119955noreply@blogger.comBlogger118125tag:blogger.com,1999:blog-6156940350159100953.post-11533413602800685192015-10-31T05:27:00.001-07:002015-10-31T05:27:13.775-07:00All five EddingtonSafety videos in one playlist<iframe allowfullscreen="" frameborder="0" height="344" src="https://www.youtube.com/embed/videoseries?list=PLiC0LFNhc8nXhNDSDGY0Kej475NGUmCF1" width="425"></iframe>David MacKay FRShttp://www.blogger.com/profile/08023079754784119955noreply@blogger.com0tag:blogger.com,1999:blog-6156940350159100953.post-38508580073312027442015-10-30T15:36:00.001-07:002015-10-30T15:36:32.674-07:00EddingtonSafety - Part 4: Comparison of Huntingdon Road with similar maj...<iframe allowfullscreen="" frameborder="0" height="344" src="https://www.youtube.com/embed/3gFJLvRPF0Q" width="459"></iframe><br /><br />
<br /><br />
People who care about Cambridge,<br /><br />
Please sign our petition and share with friends - <br /><br />
http://www.ipetitions.com/petition/EddingtonSafety<br /><br />
Thanks!<br /><br />
<br />David MacKay FRShttp://www.blogger.com/profile/08023079754784119955noreply@blogger.com0tag:blogger.com,1999:blog-6156940350159100953.post-81550913482254536922015-10-30T13:07:00.001-07:002015-10-30T13:07:25.351-07:00EddingtonSafety 3 - the Bunker's Hill / Girton Road Crossing<iframe allowfullscreen="" frameborder="0" height="344" src="https://www.youtube.com/embed/ivs9yio9M5A" width="459"></iframe><br /><br />
<br /><br />
Please sign our petition http://www.ipetitions.com/petition/EddingtonSafety and forward this to friends, especially if you have Cambridge connections.<br /><br />
Thanks!David MacKay FRShttp://www.blogger.com/profile/08023079754784119955noreply@blogger.com0tag:blogger.com,1999:blog-6156940350159100953.post-23918897845356965092015-10-30T13:06:00.001-07:002015-10-30T13:06:22.998-07:00EddingtonSafety Part 2 - Detailed problems and solutions for the Hunting...<iframe allowfullscreen="" frameborder="0" height="344" src="https://www.youtube.com/embed/DdR0LehNNkQ" width="459"></iframe><br /><br />
Please sign our petition: http://www.ipetitions.com/petition/EddingtonSafety<br /><br />
<br />David MacKay FRShttp://www.blogger.com/profile/08023079754784119955noreply@blogger.com0tag:blogger.com,1999:blog-6156940350159100953.post-63053424457870467172015-10-28T16:11:00.001-07:002015-10-28T16:11:13.412-07:00A new video explaining our "EddingtonSafety" petition for Safer Walking and Cycling near North West Cambridge<iframe allowfullscreen="" frameborder="0" height="344" src="https://www.youtube.com/embed/hIlQAzsU0js" width="459"></iframe><br /><br />
<br /><br />
Please sign our petition at<br /><br />
<a href=http://www.ipetitions.com/petition/EddingtonSafety>www.ipetitions.com/petition/EddingtonSafety</a><br />
- for further information, see:<br /><br />
<a href=http://tinyurl.com/EddingtonSafety>tinyurl.com/EddingtonSafety</a><br />
<br />David MacKay FRShttp://www.blogger.com/profile/08023079754784119955noreply@blogger.com0tag:blogger.com,1999:blog-6156940350159100953.post-8426448842822672662015-10-11T16:51:00.000-07:002015-10-11T16:51:10.101-07:00How to design climate negotiations: use the science of cooperation! <div dir="ltr" style="text-align: left;" trbidi="on">
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgDOi5E9JVEo0tDz466M6X_MlDcK6yzJqorsCV3qRXdO5zONsLHCkklf2fpxXUjcbyfgOhhJqb66WSSCrkihld-G0gLgeBORA70OLGr5bE09VT8Yka55exjQGfLyGbeDr7dhQOJifDD0Jng/s1600/IWill.png" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgDOi5E9JVEo0tDz466M6X_MlDcK6yzJqorsCV3qRXdO5zONsLHCkklf2fpxXUjcbyfgOhhJqb66WSSCrkihld-G0gLgeBORA70OLGr5bE09VT8Yka55exjQGfLyGbeDr7dhQOJifDD0Jng/s200/IWill.png" /></a></div>
<h2>Price Carbon – I will if you will</h2>
<br>
<b>
David J C MacKay FRS,
Peter Cramton,
<br>
Axel Ockenfels, and Steven Stoft
<br> </b>
<br>
<a href=http://www.nature.com/news/price-carbon-i-will-if-you-will-1.18538><em>Nature</em> Vol 526 Page 315-316 | 15 October 2015</a>
<br><br>
I think this is the most important piece of writing I have ever been involved in.
<br>
<br>
<h2>Summary</h2>
International negotiations can and should be <b>designed</b> in way that takes into
account the <b>science of cooperation</b>.
<br><br>
<b>Reciprocity</b> is the key to realigning self-interests and promoting cooperation.<br>
"Individual commitments" and "reviews" will not solve the tragedy of the commons.<br>
A <b>common commitment</b>
("I will if you will") <em>can.</em>
<br><br>
What sort of common commitment would work best?
<br>
We argue that a <b>global carbon-price commitment</b> could yield a strong treaty,
especially if coupled to <b>Green Fund transfers</b>, incentivizing low-emitting countries
to support a high carbon price.
<br><Br>
Read
<a href=http://www.nature.com/news/price-carbon-i-will-if-you-will-1.18538>the comment on
Nature's website</a>, and for further details see <a href=http://carbon-price.com>carbon-price.com</a>.
<br /></div>David MacKay FRShttp://www.blogger.com/profile/08023079754784119955noreply@blogger.com0tag:blogger.com,1999:blog-6156940350159100953.post-47889505131129773962015-09-15T09:17:00.001-07:002015-09-15T09:17:16.192-07:002016 Breakthrough Paradigm Award!<div dir="ltr" style="text-align: left;" trbidi="on">
<div class="separator" style="clear: both; text-align: center;"><a href="http://thebreakthrough.org/images/main_image/David_MacKay.jpeg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://thebreakthrough.org/images/main_image/David_MacKay.jpeg" /></a></div>
<a href=http://thebreakthrough.org/index.php/dialogue/paradigm-award-winners/david-mackay-announced-as-2016-paradigm-award-winner>I've been awarded the 2016 Breakthrough Paradigm Award</a> -- here is the nice letter I received from Shellenberger and Nordhaus:
<br><Br>
<table bgcolor="#ffffee"><tr><td> </td><td>
We are pleased to inform you that you have been awarded the 2016 Breakthrough Paradigm Award. This annual prize honors those whose work has made a major contribution to realizing a future where all the world’s inhabitants can enjoy secure, free, prosperous, and fulfilling lives on an ecologically vibrant planet.
<br>
You were chosen in recognition of your path-breaking scholarship and public service on clean energy, energy systems, and innovation. Your influential text Sustainable Energy – without the hot air continues to be an invaluable resource to the popular and policy conversations on climate change. Your commitment to accessibility, both at the sentence level and in your efforts to make your books available for free, distinguishes you among many scholars and academics working today.
<br>
We are especially pleased to honor your five years of public service at the UK Department of Energy and Climate Change, and your work steering Britain toward one of the most ambitious and pragmatic climate policy trajectories in the world.
<br>
Your work has had a significant influence on our thinking about energy technologies and transitions, including on how we train our junior fellows to understand the cost, impact, and scale of energy transitions. Your work has made the global energy conversation less dogmatic and moved the world closer to more rational and effective action.
<br>
...
<br>
We hope the prize helps expand the valence of your work, introducing new scholars both young and old to Sustainable Energy – without the hot air. Of all the “Great Transformations” achieved by societies, energy transformations are perhaps the greatest and most central. You understand these transformations better than almost anyone living, and your writings will no doubt be read far and wide in the decades to come.
<br>
We offer our congratulations and deepest thanks for your inspiring work, and we look forward to meeting you soon.
<br>
Sincerely,
<br>
Michael Shellenberger and Ted Nordhaus
</td></tr></table>
<br /></div>David MacKay FRShttp://www.blogger.com/profile/08023079754784119955noreply@blogger.com1tag:blogger.com,1999:blog-6156940350159100953.post-21713163833476040732015-08-30T02:44:00.002-07:002015-08-30T03:03:01.488-07:00Some SEWTHA updates (video, html, and hype)<div dir="ltr" style="text-align: left;" trbidi="on">
<b>Three pieces of news...</b>
<h2>1: Updated SEWTHA video</h2>
There is a new release of my 2010 "Sustainable Energy - without the hot air" lecture at Caltech
which includes close-captioning. Thank you, CMU, for providing the cc!
<br>
<table><tr><td>Original version: <A href=https://octopus.caltech.edu/ccser/video/david-mackay/index.html>Sustainable Energy - without the hot air</a> - David MacKay lectures at <b>Caltech</b>, April 2010
<br>
<b><a href=http://youtu.be/bwTiN9enSUY>NEW: on YOUTUBE with close-captioning</a></b> <small><small><small>
kindly provided by CMU's Equal Opportunity Services
</small></small></small>
</td><td>
<a href=http://youtu.be/bwTiN9enSUY><img src="http://www.inference.eng.cam.ac.uk/sustainable/images/CaltechDJCM33P.png" alt="Caltech DJCM" width="156" height="116"></a>
</td></tr></table>
<h2>2: Improving the HTML for viewing on small devices</h2>
I have made a
<A href=http://www.withouthotair.com/sewthacontentsTHIN.shtml><b>New Contents Page</b> for Sustainable Energy - without the hot air - http://www.withouthotair.com/sewthacontentsTHIN.shtml</a> which
is intended for viewing on <em>thin, small</em> displays.
This contents page enables quick navigation to any page in the book.
I recommend bookmarking it as the best quick way into the HTML book, especially on a smart-phone.
<br>
More enhancements to the HTML version of the book may be on the way soon.
<br>
For twitter users, I've added a "tweet" button to the top of every HTML page.
<h2>3: Solar and Batteries</h2>
Lots of people have asked me whether recent hype and hoopla about solar panels and batteries
overthrows what I wrote in my book in 2008.
I am preparing a detailed update. Watch this space!
The theme of my update will be the existence of a phenomenon called <b>winter</b>, which
many of the solar-hyponauts seem to ignore.
Here is a teaser trailer showing the winter and summer 3-month-average insolation in 50 US states.
<div class="separator" style="clear: both; text-align: center;"><a href="http://www.inference.phy.cam.ac.uk/mackay/presentations/html/states/HiRes/StatesNDJMJJL.eps.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" alt="winter and summer 3-month-average insolation in 50 US states" src="http://www.inference.phy.cam.ac.uk/mackay/presentations/html/states/HiRes/StatesNDJMJJL.eps.png" /></a></div>
<br /></div>David MacKay FRShttp://www.blogger.com/profile/08023079754784119955noreply@blogger.com4tag:blogger.com,1999:blog-6156940350159100953.post-80988262286199448532015-08-03T08:04:00.001-07:002015-08-03T08:38:07.801-07:00Offshore wind farm load factors<div dir="ltr" style="text-align: left;" trbidi="on">
I heard that recently-built UK offshore wind farms have higher load factors than old wind farms.
I thought it would be interesting to plot the raw data, which is available from the helpful
<a href=http://ref.org.uk/generators/index.php?start=1400&order=techdesc&dir=asc>REF website</a>.
(The load factor is the ratio of the average output of the wind farm to the maximum possible output, and it is usually
expressed as a percentage.)
The graph below shows the rolling load factor of the 27 offshore wind farms in the UK, versus their accreditation dates.
The size of each point is proportional to the capacity of the wind farm.
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiknRMZMdXSqpP65tNNhu68mXEgN6IEFhK4Huqtip_mbrZnQTM85f5YDd7yEz2BGggkq46ebS6LWZE93IhOjVbp3mUEA1z7tS_K_2Mr0BmgBiDf3QdGFKXhwnKyWjJyYhfVctbRJlftvued/s1600/offshoreLF.eps.png" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiknRMZMdXSqpP65tNNhu68mXEgN6IEFhK4Huqtip_mbrZnQTM85f5YDd7yEz2BGggkq46ebS6LWZE93IhOjVbp3mUEA1z7tS_K_2Mr0BmgBiDf3QdGFKXhwnKyWjJyYhfVctbRJlftvued/s400/offshoreLF.eps.png" /></a>
One of the newest wind farms has a very low rolling load factor - this is Gwynt y Mor, the bottom right point on the graph; Gwynt y Mor is the second biggest offshore wind farm in the world.
Presumably this poor load factor is a temporary glitch associated with the commissioning of the wind farm.
If we ignore that point as an outlier, and simply compare the average rolling load factors for accreditation dates before and after
June 30th 2010, it looks as if the average load factor may have increased from about 33.9% (± 2%) to about 37.4% (± 1%).
<br>
Of course, a proper analysis should account for ageing effects and variations in the weather, both of
which have been carefully studied by
<a href=http://www.sciencedirect.com/science/article/pii/S0960148113005727>Staffell and Green</a>.
They found that "Wind turbines ... lose 1.6 ± 0.2% of their output per year" (which implies, for a load factor
of 35%, a reduction in load factor of 0.56% per year - a trend that I have shown by the green straight line in the next graph).
<br>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhQ51RcC9MuLlFOiB2ScH3wDxXezaPAp3kfAO2GrHOhChAwdeQ1Lfzefsd5D9w6PoxQKUctu3Te3K6QDqdTKdQL8TY4nGp2490utqnLp_1fFB86cNXZqPMjWT9RcsqygryqSzXAFB9yxfik/s1600/offshoreLFSG.eps.png" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhQ51RcC9MuLlFOiB2ScH3wDxXezaPAp3kfAO2GrHOhChAwdeQ1Lfzefsd5D9w6PoxQKUctu3Te3K6QDqdTKdQL8TY4nGp2490utqnLp_1fFB86cNXZqPMjWT9RcsqygryqSzXAFB9yxfik/s400/offshoreLFSG.eps.png" /></a>
<br>
So, has there been a technological improvement in offshore wind turbines that has boosted load factors?
Having been involved in innovation support while I worked at DECC, my prior expectation was that the answer to this
question could easily be "yes".
But actually it looks like it is possible to account for the apparent trend in the data by a simple "ageing" hypothesis: perhaps the
newer wind farms are better just because they have aged less?
<br /></div>David MacKay FRShttp://www.blogger.com/profile/08023079754784119955noreply@blogger.com7tag:blogger.com,1999:blog-6156940350159100953.post-24661427122541464032015-01-20T06:26:00.000-08:002015-01-21T02:02:20.177-08:00Underfloor insulation - thinking about the business case<div dir="ltr" style="text-align: left;" trbidi="on">
Having had a go at the walls, the windows, the roof,
and air-tightness, I've decided to get the last physical improvement done to our house - the floor.
</p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhSg_s7vuGMmtxlgh8yOQ1H3qJxyIFQpORG-Pm0Gblbl1eGBc_XYDbHJM01vESFenwrBfQIZU49sgLvI7bKmr-BisIUo9NemHRJ0JVI5EIX1TOs2iV00BwHg1y4bUgzdu_OmXChlpOgRRtu/s1600/DevannaHammocksM.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhSg_s7vuGMmtxlgh8yOQ1H3qJxyIFQpORG-Pm0Gblbl1eGBc_XYDbHJM01vESFenwrBfQIZU49sgLvI7bKmr-BisIUo9NemHRJ0JVI5EIX1TOs2iV00BwHg1y4bUgzdu_OmXChlpOgRRtu/s320/DevannaHammocksM.jpg" /></a> <small>(image kindly supplied by devanainsulation.co.uk)</small></div>
<p>
The area of wooden suspended floor is about 35 square metres. According to page 290 of my book, the
U-value of the floor is 0.7 W/m2/K, so the floor has a leakiness of about 25 W/K, which assuming an average
temperature
difference of 6 degrees, implies a <em>conductive</em> heat loss of 147 W (3.5 kWh/day). (The floor may also contribute some
of the <em>ventilation</em>-leakiness of the house, but I'll neglect that.)
The floor doesn't just lose heat, it also <em>feels</em> cold, and thus (a) affects quality of life, and (b)
perhaps causes us to turn up the thermostat sometimes to improve our feeling of warmth. If we manage to
keep the whole house (leakiness 240 W/K) on average 1 degree cooler thanks to improved floor insulation,
then that would be an extra 240 W of saving (<b>6 kWh/day</b>).
<br>
I didn't do an economic calculation before deciding to get the <a href=http://retrovivefloor.com/>underfloor insulation</a>.
It just feels like the right thing to do, and Retrovive was recommended by someone from Max Fordham, whose
judgement I respect highly.
Anyway, let's work out a pay-back time. The anticipated new U-value is about 0.25 W/m2/K.
It looks like the work will cost about £2900 including VAT <small>(including insulating
central heating pipes that run under the floor)</small> (for comparison we are perfectly happy to
put down new carpets over a smaller area for a cost of £1150).
If the insulation eliminates two thirds of the floor's conductive heat loss (i.e., about 2.2 kWh/day) and
delivers say one quarter of the notional 6 kWh/day saving guessed above (if we managed to turn the thermostat
down a bit), the total saving might be <b>3.7 kWh/day</b>. With gas costing 5.2p per kWh, that's 20p per day, or £70 per year. So the payback time might be about <b>41 years</b>.
<br>
If I went to the high end of all my estimates, I might imagine a saving of <b>9.5 kWh/day</b> on average, in which
case the payback would be about £180 per year and the payback time would be <b>16 years</b>.
<br>
I am expecting that the main value of this work will be the improved <b>feeling</b> of comfort.
People are happy to pay £36,000 per year to rent a family home [That's what we paid to rent a flat in London, at least].
If the home's main room feels really cosy, how
much extra would we be willing to pay? I could imagine 5% or 10%. On those grounds, the comfort of
cosiness is worth £1800 to £3600 per year. So the payback time, taking into account this benefit,
is just <b>one or two years</b>.
<br>
I will post again when the work is done! (April 2015)
<br /></div>
David MacKay FRShttp://www.blogger.com/profile/08023079754784119955noreply@blogger.com6tag:blogger.com,1999:blog-6156940350159100953.post-36187489554380857412014-11-14T02:57:00.000-08:002014-11-14T14:28:51.167-08:00Oxford's 2050 Pathway (created 2014-15)
<div dir="ltr" style="text-align: left;" trbidi="on">
I'm giving the <a href=http://www.oxfordplayhouse.com/show/?eventid=3227>Charles Simonyi Annual Lecture</a> tonight (14 November 2014) and during my talk about
<em>Why
climate change action
is difficult,
and how we can make a difference</em>,
I will mention the
<a href=http://2050-calculator-tool.decc.gov.uk/>2050 Calculator</a>, a tool to help people have
constructive conversations about Britain's energy options, and to support consensus-building.
</p>
<img src=http://www.inference.eng.cam.ac.uk/sustainable/images/webtooloverview600.jpg width=600 height=318>
<p>
The options in the calculator include lifestyle changes, and all sorts of technologies for saving energy
and sourcing low-carbon energy.
<b>I would love to help Oxford crowd-source its own 2050 pathway</b>, but there won't be time in this single lecture
to do it; so <b>here is the plan:</b>
I'll come back to Oxford in March 2015, and, with Mark Lynas and other celebrities at the <b>Oxford
Literary Festival</b>, we will find out what pathway the Oxford audience would like to choose, to keep the lights
on, have energy security, and meet the UK's legal climate change targets .
To ensure that we have a really good deliberative discussion, the Oxford community is
welcome to use the comments area of this blog page as a place for
discussion. <br><em><b>Commenting rules:</b> Please discuss options in the calculator, and what you would like the
UK to do. Please don't have a pub brawl. Please discuss pathways
that add up. It's fine to say you dislike an option, but you should feel an obligation to describe
how you would propose to get by without that option, taking into account other people's views about the
other options. </em><br>
At the Oxford Literary Festival event we will take all your comments into account and use them as a springboard
for a really constructive discussion. Thank you for joining in!
</p>
<p>
You may be interested to see what pathways other cities chose, when they took on the
"British Energy Challenge" -
<a href=http://www.inference.eng.cam.ac.uk/mackay/decc/cities.html>here are those cities' choices, and
my reflections on the British Energy Challenge roadshows of 2013 and 2014</a>.
</p>
<p>
I look forward to listening in and supporting Oxford's energy pathway discussion in 2015!
</p>
<p>
<a href=http://www.inference.eng.cam.ac.uk/mackay/presentations/Simonyi2014/>My Simonyi lecture slides are here</a>, and <a href=http://www.withouthotair.com/>Sustainable Energy - without the hot air</a> is free online too. The 2050 Calculator also contains lots of well-written
documentation [click on the blue "i" icons] to help guide your decisions. </p>
<br /></div>
David MacKay FRShttp://www.blogger.com/profile/08023079754784119955noreply@blogger.com5tag:blogger.com,1999:blog-6156940350159100953.post-25292710135082640832014-09-10T10:19:00.000-07:002014-09-10T13:29:57.767-07:00Solar power from space?<div dir="ltr" style="text-align: left;" trbidi="on">
<br /></div>
When I published <a href=http://www.withouthotair.com/>Sustainable Energy - without the hot air</a>, there were quite a few topics I could have included but didn't because they seemed a little too blue-sky. For example I have draft chapters on Osmotic Power and on Kite Power (and if I were to rewrite the book today I think that I would now include Kite Power after all). Another idea I dismissed at the time was "what if we put solar panels in space, in geo-synchronous orbit?" I dismissed that idea on the grounds that "the advantage of space over the deserts of Libya and Nevada as a location for solar panels is only roughly a factor of 4, and surely that's outweighed by the difficulty and cost of getting panels (and associated power-re-transmission systems) into space, compared with just plopping them on the ground in a desert?" However,
<a href=http://theenergycollective.com/keith-henson/362181/dollar-gallon-gasoline>Keith Henson has for some time been working out the details of a scheme that might prove me wrong</a>.
<div class="separator" style="clear: both; text-align: center;"><a href="http://theenergycollective.com/sites/theenergycollective.com/files/imagepicker/561856/SkylonLaserSmall.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://theenergycollective.com/sites/theenergycollective.com/files/imagepicker/561856/SkylonLaserSmall.jpg" /></a></div>
It involves many clever ideas, and some ambitious ones - such as the idea of powering a Skylon freight-delivery space-craft by space lasers that are powered from the ground with GW-scale microwave transmitters! I encourage people who are interested to read <a href=http://theenergycollective.com/keith-henson/362181/dollar-gallon-gasoline>Keith's 'dollar a gallon' post</a> and <a href=http://theenergycollective.com/keith-henson/485571/power-satellite-progress>his follow-up post</a>.
<hr>
<b>Further reading:</b> <em>
<a href=http://www.inference.phy.cam.ac.uk/sustainable/book/tex/RSsolar.html>Solar energy in the context of energy use, energy transportation, and energy storage</a></em> - a paper in which I provide data for the power per unit area of real solar farms, and discuss the need for significantly cheaper energy storage if ground-based solar power is ever to contribute a significant fraction of energy consumption. David MacKay FRShttp://www.blogger.com/profile/08023079754784119955noreply@blogger.com12tag:blogger.com,1999:blog-6156940350159100953.post-36547747826094116802014-08-12T03:13:00.001-07:002014-08-12T14:13:31.584-07:00Shale gas in perspective<div dir="ltr" style="text-align: left;" trbidi="on">
<h3>How would the footprint of a shale gas operation compare with the footprint of
other ways of delivering a similar quantity of energy?</h3>
<p>
There are many dimensions to a "footprint". In this blog post, I'll look at <b>land area</b>, <b>vertical
height</b>, and <b>vehicle movements</b>.
</p><p>
I'll compare a <b>shale gas pad</b> (which might produce 0.9 billion cubic metres of gas
over 25 years) with a 174-MW <b>wind farm</b> and a 380-MW <b>solar park</b>, both of which
would deliver roughly 9.5 TWh of electricity over 25 years – the same amount of
energy as the chemical energy in 0.9 billion cubic metres of gas.
</p><p>
In this table I've highlighted in green the "winning" energy source for each of the
footprint metrics.
</p>
<p>
<table bgcolor=#ddeeee><tr bgcolor=#eeffff><td></td><td>Shale gas pad</td><td>Wind farm</td><td>Solar park</td></tr><tr><td></td>
<td>(10 wells)</td><td>87 turbines,<br> 174 MW capacity</td><td>1,520,000 panels,<br> 380 MW capacity</td></tr>
<tr bgcolor=#eeeeee><td>
Energy delivered over 25 years</td><td>9.5 TWh</td><td> 9.5 TWh</td><td>
9.5 TWh</td></tr><tr bgcolor=#eeeeee>
<td></td><td> (chemical)</td><td> (electric)</td><td> (electric)</td>
</tr>
<tr><td>
Number of tall things</td><td bgcolor=#ffffcc> 1 drilling rig</td><td > 87 turbines</td><td bgcolor=#ccffcc> None</td></tr>
<tr><td>
Height </td><td> 26 m</td><td> 100 m</td><td bgcolor=#ccffcc> 2.5 m</td></tr>
<tr><td>
Land area occupied by
hardware, foundations, or
access roads</td><td bgcolor=#ccffcc> 2 ha </td><td> 36 ha </td><td> 308 ha</td></tr>
<tr><td>
Land area of the whole facility</td><td bgcolor=#ccffcc> 2 ha </td><td> 1450 ha </td><td> 924 ha</td></tr><tr><td>
Area from which the facility can
be seen</td><td bgcolor=#ccffcc>
77 ha </td><td> 5200-17,000 ha </td><td> 924 ha</td></tr><tr><td>
Truck movements </td><td bgcolor=#fefecc> 2900-20,000 </td><td bgcolor=#fefecc> 7800 </td><td bgcolor=#fefecc> 3800 (or <abbr title="changed from 7600 to 3800 on 12 Aug 2014 in response to Chris Goodall's comments">7600<sup>*</sup></abbr>)</td></tr></table>
</p>
<p>
The <b>total land area</b> of the facility is smallest for the shale gas pad, and largest for
the wind farm. The land area actually occupied by stuff is smallest for the shale gas
pad, and largest for the solar park – the wind farm has lots of empty land between
the turbines, which can be used for other purposes.
</p>
<p>
In terms of <b>visual intrusion</b>, the wind turbines are the tallest, and could be seen
from a land area of between 52 and 170 square km, depending how they are laid
out. (To roughly estimate an area of visual influence, I computed the land area within
which the drilling rig or a wind turbine would be higher than 3 degrees above the
horizon, assuming a flat landscape.) By this measure, the shale gas pad creates the least visual intrusion.
Moreover, the drilling rig might be in place for only the first few years of operations at
the shale gas pad. The solar panels are the least tall, but the solar facility occupies
450 times as much land area as the shale gas pad. (I've assumed that the wind farm
and solar parks wouldn't require any additional "intrusive" electricity pylons.)
</p>
<p>
When it comes to <b>truck movements</b>, all three energy facilities require lots! I've
assumed that solar panels are delivered at a rate of 800 (originally <abbr title="changed from 400 to 800 on 12 Aug 2014 in response to Chris Goodall's comments">400<sup>*</sup></abbr>) panels per truck; for the
wind farm, my estimate is dominated by the delivery of materials for foundations and
roads at 30 tonnes per truck; the estimates for the shale gas pad are from DECC's
recent Strategic Environmental Assessment and from the Institute of Directors' report
"Getting Shale Gas Working". The shale gas pad might require the fewest truck
movements, <em>if all water is piped to and from the site</em>. But if water for the fracking is
trucked to and from the site, then the shale-gas facility would require the most truck
movements.
</p>
<p>
<b>What can we take from these numbers?</b>
Well, perhaps unsurprisingly, there is no silver bullet – no energy source with all-round small environmental impact. If society wants to use energy, it must get its
energy from somewhere, and all sources have their costs and risks.
I advocate deliberative conversations in which the public discuss <a href=http://2050-calculator-tool.decc.gov.uk/>the whole
energy system</a> and look at all the options.
</p><p>
Thanks to Jenny Moore, Martin Meadows, and James Davey for helpful discussions.
</p>
<div class="separator" style="clear: both; text-align: center;"><table><tr><td>
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgYoDSVeWrZ41vn8pYQte2IKaRuU7eA2eKz9bcb7F10omMSt33zmLvyJryhajcevqci4yEgAghB-DZE8Yta8pju0ebTyMZBWyGbK3tN1JMgRf0YiAW0lepo2QIf8LA5BWfaIEF2BPzhajMY/s1600/SPOT19731_YokogawaUKWytchFarm.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;">
<img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgYoDSVeWrZ41vn8pYQte2IKaRuU7eA2eKz9bcb7F10omMSt33zmLvyJryhajcevqci4yEgAghB-DZE8Yta8pju0ebTyMZBWyGbK3tN1JMgRf0YiAW0lepo2QIf8LA5BWfaIEF2BPzhajMY/s320/SPOT19731_YokogawaUKWytchFarm.jpg" /></a></td><td><small><b>Photo:</b> Wytch Farm, on the perimeter of Poole Harbour in Dorset, is the largest
onshore oil and gas field in Western Europe. It is located in an Area of Outstanding
Natural Beauty. The photograph shows the 34-metre-high extended-reach drilling rig,
from which boreholes longer than 10 km have been drilled.</small></td></tr></table></div>
<small>
<h4>Comments and clarifications</h4>
<p> All estimates are for energy production facilities located in the UK.
The estimate of energy produced from a shale gas pad is highly uncertain, since
there are no data for actual shale gas production in the UK.
</p>
<p>
The comparison in the table is based on deeming 1 kWh of electrical output from the wind to be
'equivalent' to 1 kWh
of chemical energy in the form of gas.
This is the conventional equivalence used for example in <a href=https://www.gov.uk/government/collections/digest-of-uk-energy-statistics-dukes>DUKES</a> and in
<a href=http://www.withouthotair.com/>Sustainable Energy - without the hot air</a>.
The following differences between the energy sources should be noted.
<ol>
<li>
The three sources of power have different profiles of power generation.
On an annual scale, a
single shale gas well produces most power when it is newly fractured,
whereas a wind-farm produces a relatively constant average power
over its life. On an hour-by-hour scale, the gas from the well is
dispatchable – its flow can be turned up and down at will – whereas
the power from a wind-farm is intermittent.
</li><li>
In a world in which the only conceivable use for gas is making electricity
in a power station with an efficiency of about 50%, one might prefer to
deem each 1 kWh of gas as 'equivalent' to just 0.5 kWh of electricity.
</li><li>
On the other hand, in a world that values gas highly relative to electricity
that is generated at times when the wind blows,
one might imagine
planning (as Germany is said to be planning)
to use electricity from wind-farms to synthesize methane (with an
efficiency of 38-48%); then one might deem each 1 kWh of wind-electricity
as being 'equivalent' to 0.38-0.48 kWh of gas.
</li><li>
If one wished to make a comparison in which both power sources are constrained
to have very low carbon emissions,
the shale-gas well must be accompanied by other assets.
For example, if the gas is sent to a power station that performs
carbon capture and storage, the gas-to-carbon-free-electricity efficiency
might be about 42%, and the land area for the power station and
the carbon
transport and storage infrastructure should be included;
assuming that these assets have an area-to-power ratio
of 100 ha per GW(e),
each 43.4-MW gas well (which would yield 18.2 MW of electricity)
would require an extra 1.82 ha of land, which roughly doubles the
2-ha land area mentioned in the table.
</li></ol>
</p>
<p>
My estimate for vehicle movements for large wind-farms is based on Farr wind-farm.
I'm sure there is considerable variation from project to project, and I would welcome
more data.
For the number of truck movements required for a wind farm, I reckoned
there would be about 870 movements to bring in the
turbines themselves [counting an in-bound and out-bound trip as two movements],
and significantly more movements to bring in the materials
for roads and concrete for foundations. Some of these materials may be
mined from quarries located on the wind-farm, which would then involve no vehicle movements
on public roads; based on Farr wind-farm
(where three quarters of the road materials were sourced on site) [sorry, I don't have
a link for this fact],
the road building would require 2774 vehicle movements for a 174-MW
windfarm, and the foundations would require another 4140 or so –
in total, about
7800 vehicle movements.
</p>
</small>
<h4>Further reading</h4>
<a href=https://www.gov.uk/government/publications/potential-greenhouse-gas-emissions-associated-with-shale-gas-production-and-use>Potential greenhouse gas emissions associated with shale gas production and use</a>.
<br /></div>
David MacKay FRShttp://www.blogger.com/profile/08023079754784119955noreply@blogger.com37tag:blogger.com,1999:blog-6156940350159100953.post-14948964008526206342014-08-07T08:49:00.003-07:002014-08-07T08:49:49.393-07:00Embodied energy in a car - update under way<div dir="ltr" style="text-align: left;" trbidi="on">
<p>
John Biggins sent me a helpful email querying a number in <a href=http://www.withouthotair.com/c15/page_90.shtml>my book's chapter on "Stuff"</a>.
<br>
<em>
I have a question about the embedded energy in a car, which you quote at 76000kWh. That seems awfully high to me. To a first approximation a car is a tonne of steel, with a raw material energy of 6000kWh: an order of magnitude less.The (admittedly biased) Society of Motor Manufacturers & Traders
<a href=
http://www.smmt.co.uk/wp-content/uploads/sites/2/9th+smmt+sustainability+report-final.pdf >report</a>
quote an even lower figure of 2000kWh per car (page 17), which I suspect is probably meant to be simply the energy used per car by the car plant, neglecting materials.
<br>
The guardian also wrote about this in <a href=
http://www.theguardian.com/environment/2009/aug/17/car-scrap-energy-efficiency>2009</a>
. <br>
They asked a few manufacturers, and arrive at a figures in the ballpark of about 1-4 tonnes of C02 to produce a car, which we might reverse engineer guessing most of the CO2 comes from coal burning in either steel production or electricity generation, to get ballpark figures of probably no more than 10,000kwh per car.
<br>
Since these estimates actually differ from your figure by a magnitude, I thought I'd write and ask whether you particularly believe your 76,000kWh figure. Do you have any back-of-the-envelope type way to understand it?
</em>
</p>
<div class="separator" style="clear: both; text-align: center;"><a href="http://www.withouthotair.com/cA/figure252.png" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" src="http://www.withouthotair.com/cA/figure252.png" /></a></div><p>
This blog post is where I will record my working on this question. I will aim to justify or adjust my answer within a month,
and will add to the book's <a href=http://www.withouthotair.com/Errata.html>Errata</a> if necessary. If anyone wants to send me good references on embodied-car-energy to
add to my own, please post a comment. Thanks!
David
</p>
<br /></div>
David MacKay FRShttp://www.blogger.com/profile/08023079754784119955noreply@blogger.com7tag:blogger.com,1999:blog-6156940350159100953.post-86381097414074625122014-06-23T09:25:00.001-07:002014-06-23T09:36:55.126-07:002014 Longitude Prize Water Challenge<TABLE width=800><!-- This is the master table inside which everything sits-->
<tr bgcolor=#002266><td width=100% bgcolor=#001155 height=122 valign=center><!-- This is the master table's opening line and logo -->
<TABLE width=306 cellpadding=0 cellspacing=0><tr><td width=102 height=61></td><td>
<a href=http://www.longitudeprize.org/><img src="http://www.inference.eng.cam.ac.uk/sustainable/images/longitude205.png" alt="longitude205" width="204" height="61" border=0></a></td></tr></table>
</td></tr>
<tr><td><!-- This is the master table, second row -->
<table width=100% cellspacing=0 cellpadding=0><tr><td width=400>
<p>
Clean water is crucial not only for humans' direct use
but also for agriculture. Attention often focuses on drinking water,
but agriculture is far bigger.
</p>
<p>
Let's put it in numbers. How much drinkable water do you require
for drinking and for cooking? Perhaps a few litres per day per
person. In the UK, urban consumption of water is about <b>160
litres per day per person</b>. And in developed countries, even if
they are being careful with water, agriculture requires about <b>340
litres per day per person</b>. <small>[Israel uses roughly 1000
million m<sup>3</sup> of water per year for agriculture, and it has
a population of roughly 8 million. That's 340 litres per day per
person.]</small>
</p>
<p>
Some lucky countries have plenty of rainfall, so this agricultural
requirement can be provided at very low cost.
But what if the water for agriculture must be produced
by desalinating sea-water?
</p>
<p><table><tr><Td valign=top>
<div class="imgcap" style="top:30em"><img style="padding-left:2em" src="http://www.withouthotair.com/c15/figure110.png" width="465" height="369" alt="a bank of reverse-osmosis membranes - photo by David MacKay"></div>
</td><td valign=top width=200>
<div><small>Part
of the reverse-osmosis facility at Jersey Water’s desalination
plant. The pump in the foreground, right, has a power of 355 kW and
shoves seawater at a pressure of 65 bar into 39 spiral-wound
membranes in the banks of blue horizontal tubes, left, delivering
1500 m<sup>3</sup> per day of clean water. The clean water from this
facility has a total energy cost of 8 kWh per m<sup>3</sup>. From <a
href=http://www.withouthotair.com/c15/page_93.shtml><em>Sustainable
Energy - without the hot air</em></a></small></div>
</td></tr></table>
<p>
Standard reverse-osmosis facilities have an energy cost of 8 kWh per
m<sup>3</sup>, so an agricultural water requirement of 340 litres per
day per person implies an energy requirement of about 2.7 kWh per day
per person, if we had to make it all by desalination with today's
technology. To put that in UK terms, 2.7 kWh/d/p is roughly 17% of
the average UK electricity supply; delivering 2.7 kWh/d/p of
electricity to the UK would require roughly 7 extra nuclear power
stations the size of Sizewell B, or 13,500 2-MW wind turbines.
</p><p>
For people in a less-developed country, the cost of desalinating that
much water would be significant - 2.7 kWh/d/p might cost
about 30 pence per day per person.
<a href=http://www.unmillenniumproject.org/resources/fastfacts_e.htm>More than a billion people
live on less than a dollar a day</a>.
</p><p>
This is why the Longitude Prize Water Challenge
sets the goal of desalinizing water with significantly
less energy than today's technologies.
We are especially interested in approaches that could be low-enough
in cost not only at large scale but also when rolled out in small-scale facilities.
</p>
</td></TR><TR><TD> <!-- Master table row N-2 -->
<small>
For an example of an inventive approach to the Water Challenge,
Stephen Salter has
<a href=http://www.see.ed.ac.uk/~shs/Desalination/>published
a wave-powered desalination invention (2007)</a> using <em>vapour-compression desalination</em>
in place of reverse osmosis.
<center>
<a href=http://www.see.ed.ac.uk/~shs/Desalination/Edinburgh%20wave%20desalination.pdf><img src="http://www.inference.eng.cam.ac.uk/sustainable/images/VapourCompressionSalter2007.png" alt="sustainableimages/VapourCompressionSalter2007" width="579" height="746"></a>
</center>
</small>
</td></TR><TR><TD> <!-- Master table row N-1 -->
<hr>
<a href=http://www.bbc.co.uk/programmes/b006mgxf/vote>Voting for the Longitude Prize Challenge closes at 7.10pm on June 25th 2014.
<br>
<b>See also:</b> <a href=http://withouthotair.blogspot.co.uk/2014/06/2014-longitude-prize-flight-challenge.html>2014 Longitude prize FLIGHT Challenge</a>
</a>
<hr>
<p><em>
David MacKay FRS is a member of the
<a href=http://www.longitudeprize.org/>2014 Longitude</a> Committee. He is
the Chief Scientific Advisor at the Department of Energy and Climate
Change, and Regius Professor of Engineering at the University of
Cambridge. He is well known as author of the popular science book,
<em><a href=http://www.withouthotair.com/>Sustainable Energy —
without the hot air</a></em>.
</em>
</p>
</td></TR><TR><TD> <!-- Master table row 3 -->
<hr>
<address><a href="http://www.inference.eng.cam.ac.uk/mackay/">David MacKay FRS</a> </address>
<!-- end of master table -->
</td></tr>
</table>
</td></tr>
</table>
<div dir="ltr" style="text-align: left;" trbidi="on">
<br /></div>
David MacKay FRShttp://www.blogger.com/profile/08023079754784119955noreply@blogger.com1tag:blogger.com,1999:blog-6156940350159100953.post-48667323362700925282014-06-23T09:10:00.001-07:002014-06-23T09:38:00.348-07:002014 Longitude Prize Flight Challenge
<TABLE width=800><!-- This is the master table inside which everything sits-->
<tr bgcolor=#002266><td width=100% bgcolor=#001155 height=122 valign=center><!-- This is the master table's opening line and logo -->
<TABLE width=306 cellpadding=0 cellspacing=0><tr><td width=102 height=61></td><td>
<a href=http://www.longitudeprize.org/><img src="http://www.inference.eng.cam.ac.uk/sustainable/blog/sustainableimages/longitude205.png" alt="longitude205" width="204" height="61" border=0></a></td></tr></table>
</td></tr>
<tr><td><!-- This is the master table, second row -->
<table width=100% cellspacing=0 cellpadding=0><tr><td width=400>
<p>
The aviation industry has made amazing progress. In just 111 years
since the first controlled, powered, heavier-than-air flying-machine
flew in North Carolina, innovators and industry have produced a
spiralling succession of biplanes, monoplanes, jet aircraft,
helicopters, airliners, and faster-than-sound planes. Thanks to
steady advances in engineering and materials science, aviation records
are repeatedly broken; aircraft are getting steadily lighter and more
energy efficient. The Boeing 747 travels 20 times faster than an
ocean liner, but uses <a href=http://www.withouthotair.com/c20/page_128.shtml>less than half as much energy per
passenger-kilometre</a>; if all its seats are occupied, a 747 is <a href=http://www.withouthotair.com/c20/page_128.shtml>as
energy-efficient as a standard (33 miles-per-gallon) car with two
people in it</a>, even though the plane goes ten times as fast as the
car. And the latest <a href=http://www.atraircraft.com/media/downloads/brochure%20ECO_light.pdf>ATR72 turboprop</a> is said to be 40% more energy-efficient than
the 747<a href=http://www.inference.eng.cam.ac.uk/sustainable/book/errata/turboprop.html>.</a>
</p>
</td><td valign=top cellpadding=4 width=400>
<img src="http://www.inference.eng.cam.ac.uk/sustainable/blog/sustainableimages/HybridAir_BagatelleCCSS.jpg" title="Alberto Santos-Dumont's combined aircraft/dirigible experiments of 1906" width="398" height="200">
</td></tr></table>
<p>
But if the world is serious about tackling climate change, these fantastic engineering achievements are not enough. Whereas, in the year 2000, aviation contributed 2% of global carbon dioxide emissions, it is projected that by 2050, aviation's growth will increase its carbon emissions five-fold, even allowing for continued improvements in efficiency. Moreover, today's planes emit other greenhouse gases whose effect on climate is estimated to be between two and four times greater than their carbon dioxide emissions.
</p><p>
The Longitude Prize 2014 Flight Challenge sets a new goal for aviation: to design and demonstrate a <em>near-zero-carbon</em> aircraft, which travels <em>fast</em> (though not necessarily as fast as a jet), which has a substantial <em>range</em> (at least London to Edinburgh!), and which is significantly more <em>energy-efficient</em> than a 747.
There is no simple solution to this demanding set of constraints, but there are
promising approaches that fulfill <em>some</em> of these requirements.
</p><p>
<table width=100%><tr><td valign=top cellpadding=0 width=400>
<ul><li>
NASA's
<a href=http://cafefoundation.org/v2/gfc_main.php>2011 Green Flight Challenge</a> was convincingly won by a four-seat electric battery-powered aeroplane, the
<a href=http://www.pipistrel.si/>Pipistrel</a>
<a href=http://en.sv-jme.eu/data/upload/2011/12/02_2011_212_Tomazic_04.pdf>Taurus G4</a>,
which flew nearly 200 miles in less than two hours, with an energy efficiency equivalent to a 120 miles-per-gallon car. This astonishing achievement delivers all the requirements of the Longitude Prize Flight Challenge <em>except for the range requirement</em> — it may take significant breakthroughs in battery technology if such an aircraft is to win the Challenge.
</li></ul>
</td><td width=4></td>
<td valign=top align=right width=400 cellpadding=4>
<table cellpadding=0 cellspacing=1 bgcolor=#666666 width=400 height=206>
<tr><td>
<img src="http://www.inference.eng.cam.ac.uk/sustainable/images/PipistrelTaurusG4_NASA_photoSC.jpeg" title="PipistrelTaurusG4 NASA photo" width="398" height="206">
</td></tr></table>
</td></tr></table>
</p><p>
<table width=100%><tr><td valign=top cellpadding=0 width=400>
<ul><li>
The <a href=http://www.solarimpulse.com/>Solar Impulse</a> is an electric aircraft in which heavy batteries are replaced by huge solar panels spread over the wings and tail. It can fly for more than 24 hours and could easily make the trip from London to Edinburgh. But with a speed of only 43 miles per hour, the Solar Impulse is <em>too slow</em>.
</li></ul>
</p>
</td><td width=4></td><Td valign=top width=400 cellpadding=4>
<table cellpadding=0 cellspacing=1 bgcolor=#666666 width=400><tr><td>
<img src="http://www.inference.eng.cam.ac.uk/sustainable/images/Solar_Impulse2C.jpg" title="image from solarimpulse.com" width="400" height="260">
</td></tr></table>
</td></tr></table>
</p><p>
<table width=100%><tr><td valign=top cellpadding=0 width=590>
<ul><li>
Oxfordshire-based <a href=http://www.reactionengines.co.uk/>Reaction Engines</a>
have a completely different approach on their drawing board.
They are designing liquid-hydrogen-burning engines that could be used to launch satellites into orbit. The same engines could also power a hypersonic passenger aeroplane, the LAPCAT, which (thanks to the very high calorific value of hydrogen) could fly from London to Brisbane in a single hop. It doesn't seem likely that the LAPCAT will be more energy-efficient than a 747, but perhaps a lower-speed hydrogen-powered approach might work.
</li></ul>
</td><td width=4></td><td valign=top cellpadding=4>
<table cellpadding=0 cellspacing=1 bgcolor=#666666 width=210><tr><td>
<img src="http://www.inference.eng.cam.ac.uk/sustainable/images/lapcata2takeoff1.jpg" title="lapcat A2 image from Reaction Engines - www.reactionengines.co.uk" width="210" height="155">
</td></tr></table>
</td></tr></table>
</p><p>
<table width=100%><tr><td valign=top cellpadding=0 width=590>
<ul><li>
Cranfield-based <a href=http://www.hybridairvehicles.com/>Hybrid Air Vehicles</a> are developing aircraft that
are a cross between a regular plane and a blimp. The helium-filled
<em>Airlander</em> uses a combination of buoyancy
and aerodynamics to generate lift. Their current prototype has adequate speed and range, but its fossil-fuel-powered engines emit too much carbon and use too much energy. Perhaps a redesigned hybrid aircraft, optimized to work at a lower speed, might be significantly more energy efficient.
</li></ul>
</td><td width=4></td><td valign=top cellpadding=4>
<table cellpadding=0 cellspacing=1 bgcolor=#666666 width=400><tr><td>
<img src="http://www.inference.eng.cam.ac.uk/sustainable/images/HybridAirVehiclesM.jpg" title="Hybrid Air Vehicles prototype - http://www.hybridairvehicles.com/" width="398" height="224">
</td></tr></table>
</td></tr></table>
</p><p>
We intend the Challenge to be accessible to small creative teams.
Here I've described four current activities that indicate
the wide range of perspectives
from which the Flight Challenge might be approached.
I'm confident the Flight Challenge will stimulate brilliant inventors to develop other exciting ideas for the future of aviation.
</p>
</td></TR><TR><TD> <!-- Master table row N-2 -->
<table bgcolor=#dddddd cellpadding=2 cellspacing=2>
<tr><td colspan=2> </td><td bgcolor=#eeeeee colspan=6 align=center > criteria </td></tr>
<tr><td colspan=2> </td><td bgcolor=#eeeeee width=80>zero carbon emissions in flight
</td><td width=80 bgcolor=#eeeeee>energy-efficient
</td><td width=80 bgcolor=#eeeeee>speed
</td><td width=80 bgcolor=#eeeeee>range
</td><td width=80 bgcolor=#eeeeee> carries passengers
</td></tr>
<tr><td colspan=2 bgcolor=#eeeeee align=center>
vehicle </td></tr>
<tr><Td bgcolor=#eeeeee>
Pipistrel
Electric plane </td>
<td bgcolor=#efefef align=center cellpadding=0>
<img src="http://www.inference.eng.cam.ac.uk/sustainable/images/PipistrelTaurusG4_NASA_photoSCS.jpeg" title="PipistrelTaurusG4_NASA_photoSCS" width="180" height="93"></td>
<td bgcolor=#efefef align=center><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr> </td><td bgcolor=#efefef align=center><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr> </td><td bgcolor=#efefef align=center><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr> </td><td bgcolor=#efefef align=center><abbr title="cross"><font style="color:#ff3333;">✘</font></abbr><b>?</b> </td><td bgcolor=#efefef align=center> <abbr title="tick"><font style="color:#22dd22;">✔</font></abbr><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr>
</td></tr>
<tr>
<Td bgcolor=#eeeeee>
Reaction Engines'
LAPCAT
Hydrogen plane </td>
<td bgcolor=#efefef align=center cellpadding=0>
<img src="http://www.inference.eng.cam.ac.uk/sustainable/images/lapcata2takeoff1S.jpg" title="lapcat a2 takeoff - www.reactionengines.co.uk" width="180" height="133"></td>
<td bgcolor=#efefef align=center><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr><b>?</b> </td><td bgcolor=#efefef align=center><abbr title="cross"><font style="color:#ff3333;">✘</font></abbr> </td><td bgcolor=#efefef align=center><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr> </td><td bgcolor=#efefef align=center><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr> </td><td bgcolor=#efefef align=center><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr><b>?</b>
</td></tr>
<tr><Td bgcolor=#eeeeee>
Solar Impulse </td>
<td bgcolor=#efefef align=center cellpadding=0>
<img src="http://www.inference.eng.cam.ac.uk/sustainable/images/Solar_Impulse2CS.jpg" title="Solar_Impulse2CS" width="180" height="117"></td>
<td bgcolor=#efefef align=center><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr> </td><td bgcolor=#efefef align=center><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr> </td><td bgcolor=#efefef align=center><abbr title="cross"><font style="color:#ff3333;">✘</font></abbr><abbr title="cross"><font style="color:#ff3333;">✘</font></abbr> </td><td bgcolor=#efefef align=center><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr> </td><td bgcolor=#efefef align=center><abbr title="cross"><font style="color:#ff3333;">✘</font></abbr>
</td></tr>
<tr><Td bgcolor=#eeeeee>
Hybrid Air Vehicles</td>
<td bgcolor=#efefef align=center cellpadding=0>
<img src="http://www.inference.eng.cam.ac.uk/sustainable/images/HybridAirVehiclesS.jpg" title="HybridAirVehiclesS" width="180" height="101"></td>
<td bgcolor=#efefef align=center><abbr title="cross"><font style="color:#ff3333;">✘</font></abbr><b>?</b> </td><td bgcolor=#efefef align=center><abbr title="cross"><font style="color:#ff3333;">✘</font></abbr><b>?</b> </td><td bgcolor=#efefef align=center><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr><b>?</b> </td><td bgcolor=#efefef align=center><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr> </td><td bgcolor=#efefef align=center><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr><abbr title="tick"><font style="color:#22dd22;">✔</font></abbr>
</td></tr>
</table>
</td></TR><TR><TD> <!-- Master table row N-1 -->
<hr>
<b>See also:</b> <a href=http://withouthotair.blogspot.co.uk/2014/06/2014-longitude-prize-water-challenge.html>2014 Longitude prize WATER Challenge</a>
<hr>
<a href=http://www.bbc.co.uk/programmes/b006mgxf/vote>Voting for the Longitude Prize Challenge closes at 7.10pm on June 25th 2014.
</a>
<hr>
<p><em>
David MacKay FRS is a member of the 2014
<a href=http://www.longitudeprize.org/>Longitude</a> Committee. He is the Chief Scientific Advisor at the Department of Energy and Climate Change, and Regius Professor of Engineering at the University of Cambridge. He is well known as author of the popular science book, <em><a href=http://www.withouthotair.com/>Sustainable Energy — without the hot air</a></em>.
</em>
</p>
</td></TR><TR><TD> <!-- Master table row 3 -->
<hr><small>
<h4>Frequently asked questions...</h4>
<dl><dt><b><em>What's the expected progress under business as usual, or if best efforts are made?</em></b></dt><dd>
The Advisory Council for Aeronautics Research in Europe (ACARE) have published
their vision for 2020, in which there is a target of a 50% reduction in CO<sub>2</sub>
emissions per seat-km by 2020, relative to a base year of 2000. Of this 50%, <b>40%</b>
is attributed to aircraft-level improvements [in new aircraft], while 10% comes from operational
improvements.
From 1961 to 2000, aircraft <em>engines</em> have become roughly 40% more efficient [Comet 4 to B777-200],
and aircraft have become 70% more efficient overall (in fuel per seat-km). However, improving
an engine's fuel efficiency tends to make its NOx emissions worse.
<a href=https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/4515/future-aircraft-fuel-efficiency.pdf>Future Aircraft
Fuel Efficiencies
-
Final Report
Gareth Horton (92 pages)</a>
Horton reckons the <em>upper bound</em> of likely efficiency improvements, in 2050, relative to 2000, is 71%
for single-aisle aircraft.
<br>
<a href=http://dspace.mit.edu/bitstream/handle/1721.1/62196/Lovegren_ICAT-2011.pdf?sequence=1>ESTIMATION OF POTENTIAL AIRCRAFT FUEL BURN REDUCTION IN CRUISE VIA SPEED AND ALTITUDE OPTIMIZATION STRATEGIES
Jonathan A. Lovegren
and R. John Hansman - MIT Report No. ICAT-2011-03
February 2011 </a> focuses on the potential efficiency
benefits that can be achieved by improving
the cruise speed and altitude profiles operated by
flights today in the USA.
Their results indicate that a maximum fuel burn reduction of 3.5% is possible in cruise given
complete altitude and speed optimization, which corresponds to <b>2.6% fuel reduction</b> system-wide.
</dd>
<dt><b><em>Isn't this a solved problem? Can't we just use
biofuel, especially drop-in bio-replacements for kerosene?</em></b></dt><dd>
Biofuels are often assumed to be "the answer" for aviation, and they
may play an important role.
There are three reasons for looking for other solutions.
<ol>
<li> A biofuel-derived kerosene substitute, even
if truly carbon neutral, will still cause the
other [non-CO<sub>2</sub>] greenhouse-gas emissions
(for example NOx), which are estimated to have at least as big
a climate-change impact as the CO<sub>2</sub> from planes.
</li><li>
The land requirements for a biofuel solution would be substantial:
if we take the IPCC's projection for global aviation's fuel
demand in 2050 [equivalent to 2.5 GtCO<sub>2</sub>/y],
and assume that biofuel [equivalent to 240 g/kWh]
is produced with a land-productivity of 0.5 W/m<sup>2</sup>,
we find the land required for biofuel production would be 2.4
million km<sup>2</sup>, which is (1/4) of the USA, 10 times the
UK's area, or 100 Waleses. (1 Wales is roughly the same as
1 New Jersey.)
These land requirements may be in tension with other desires for
environmental sustainablity and food production.
</li><li>
Biofuels are not necessarily "zero-carbon".
Some biofuels require substantial energy
for their production; and some forms of biofuel production
may involve changes in carbon stocks in the landscape, compared
to alternative uses of the land, such that the use of the biofuel
causes substantial net carbon emissions. These land-use-change
emissions may be "one-off" emissions [i.e., incurred
once only], but that does mean they can be neglected.
</li>
</ol>
</dd>
<dt><b><em>How can electric or hydrogen planes be counted as zero-carbon? Where does the electricity or hydrogen come from?</em></b></dt><dd>
Yes, "decarbonizing" by switching to electricity makes
sense only if there is a proportional additional increase in
low-carbon electricity generation. For hydrogen to be considered
zero-carbon, it would eventually have to be produced from
zero-carbon electricity by electrolysis,
or at a carbon-capture-and-storage facility.
</dd>
<dt><b><em>What if we make artificial kerosene from CO<sub>2</sub> and
a zero-carbon energy source?</em></b></dt><dd>
Yes, artifical fuel synthesis is an important technology option
to develop. It avoids the land-requirements and
sustainability concerns about biofuels, and instead requires
substantial additional energy inputs.
<ol>
<li> "Zero-carbon"
artifical kerosene will still cause the
other [non-CO<sub>2</sub>] greenhouse-gas emissions
(for example NOx), which are estimated to have at least as big
a climate-change impact as the CO<sub>2</sub> from planes.
</li>
<li>
Also, it is important to be clear whether the artifical kerosene
is truly carbon neutral; it <em>may</em> be [especially if the
CO<sub>2</sub> is captured directly from the air],
but it depends on the source of the
carbon that goes into making the fuel.
Consider for example a fossil-fuel power station with CO<sub>2</sub>
capture. If this CO<sub>2</sub> is fed to a aeroplane-fuel-synthesis
plant, then we cannot declare both the power station and the
aeroplane "zero carbon"! The right way to think about
this set-up is that it would be getting <em>two</em>
uses out of each fossil-fuel carbon atom, before it is released
as CO<sub>2</sub> by the plane.
<br>
Some fuel-synthesis proponents will suggest getting all the
required CO<sub>2</sub>
from biological sources instead - for example by capture
from the chimney of
a sustainable-biomass-powered power-station. Such an arrangement
can certainly be imagined at small scale,
but would there be enough biomass for it to work
at large scale?
</li>
</ol>
</dd>
</dl>
</small>
</td></TR><TR><TD> <!-- Master table row 3 -->
<hr>
<address><a href="http://www.inference.eng.cam.ac.uk/mackay/">David MacKay FRS</a> </address>
<!-- end of master table -->
</td></tr>
</table>
<div dir="ltr" style="text-align: left;" trbidi="on">
<br /></div>
David MacKay FRShttp://www.blogger.com/profile/08023079754784119955noreply@blogger.com2tag:blogger.com,1999:blog-6156940350159100953.post-91830097376039245752014-05-24T07:15:00.001-07:002014-05-24T07:15:17.249-07:00Energia sostenibile - senza aria fritta [Italian translation of Sustainable Energy - without the hot air!]<div dir="ltr" style="text-align: left;" trbidi="on">
<p>
I'm very grateful to volunteers Alessandro Pastore, Javier Oca, Valentina Rossi, Alberto Marcone,
Paolo Errani, and Simone Gallarini for completing the Italian translation of <a href=http://www.withouthotair.com/><em>Sustainable Energy - without the hot air</em></a>.
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjMIAXvRN1hOGFMV4OPzJU1NuhtwZBpV8BvmluFEURXFMBWzhSp48CX6FgctS-iYmAuZcgidgIsl5zCxwJznXOJ6Jbzh8akJJxf8ZjHIQgCjNfBLj9gxtrhwJ4ZMtbturX9KQyyH_xHgdBs/s1600/ItalianFig13.7.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjMIAXvRN1hOGFMV4OPzJU1NuhtwZBpV8BvmluFEURXFMBWzhSp48CX6FgctS-iYmAuZcgidgIsl5zCxwJznXOJ6Jbzh8akJJxf8ZjHIQgCjNfBLj9gxtrhwJ4ZMtbturX9KQyyH_xHgdBs/s320/ItalianFig13.7.png" /></a></div>
<a href=http://conferenzaenergia.wordpress.com/2014/05/22/energia-sostenibile-senza-aria-fritta-conoscere-per-scegliere-e-fare-la-differenza/>There is an announcement of the translation, and a synopsis, at this link</a>, and the first draft of the translation is available on
<a href=http://www.withouthotair.com/translations.html>the book's translation page</a>.
</p>
<p> <em>Energia sostenibile - senza aria fritta</em> —
<b>Nel caso ci fossero sfuggite delle imperfezioni o errori, all'indirizzo
email: <a href=mailto:energia.senzaariafritta@gmail.com>energia.senzaariafritta@gmail.com</a>, saremo ben lieti di riceverne segnalazione.</b> Il libro in italiano può essere scaricato liberamente da internet
all'indirizzo <a href=http://www.withouthotair.com/translations.html>http://www.withouthotair.com/translations.html</a>.
</p>
<p>
Grazie!
</p>
<br /></div>
David MacKay FRShttp://www.blogger.com/profile/08023079754784119955noreply@blogger.com2tag:blogger.com,1999:blog-6156940350159100953.post-31693118475295320852014-02-22T12:21:00.001-08:002014-03-16T12:36:01.302-07:00Crowd-sourcing the IET's 2050 Pathway<div dir="ltr" style="text-align: left;" trbidi="on">
I am giving the <a href=http://conferences.theiet.org/clerk-maxwell/about/index.cfm>Clerk Maxwell Lecture</a> for the IET on
6 March 2014 at the Royal Institution, London, UK.
This post and its discussion area are for the IET audience who are coming to the lecture.
<br /></div>
<p>
I'm aiming to make a highly interactive presentation in which we will try to crowd-source an "IET consensus pathway" in the UK's <a href=http://2050-calculator-tool.decc.gov.uk/pathways/1111111111111111111111111111111111111111111111111111/primary_energy_chart>2050 Calculator</a>.
To help the discussion go well, I'd like to encourage people who are planning to be in the audience, <b><em>before the lecture</em></b>, to play with the calculator, and to <b>identify the levers they would most like to discuss</b> during the lecture. Please use the comments area at the foot of this blog-post <b>now</b> as a discussion area. Please feel free also to discuss your preferred pathways or preferred settings of individual levers, and to discuss <b>particular issues or trade-offs that you think should be part of a useful conversation using the calculator</b>.
</p>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg-VLC6br3Yk1LNeLxtC2dxkCQjYUPQt0LtoFj6oxN0n3eO-WE-gGAr3-JPh6VAtOYFhPgXkQg0GfkeFXvPrXfOKwji1TV49Ws2kXsVYZ6Bc_Ch7mZzd4OPfMWW-VKVBMxLVKDI7ZHQYwKB/s1600/webtooloverview.jpg" imageanchor="1" style="margin-left:1em; margin-right:1em"><img border="0" height="212" width="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg-VLC6br3Yk1LNeLxtC2dxkCQjYUPQt0LtoFj6oxN0n3eO-WE-gGAr3-JPh6VAtOYFhPgXkQg0GfkeFXvPrXfOKwji1TV49Ws2kXsVYZ6Bc_Ch7mZzd4OPfMWW-VKVBMxLVKDI7ZHQYwKB/s400/webtooloverview.jpg" /></a></div>
<p>For background reading, please see my posts <a href=http://withouthotair.blogspot.co.uk/2012/01/version-3-of-2050-pathways-calculator.html>about version 3 of the calculator</a> and <a href=http://withouthotair.blogspot.co.uk/2011/03/public-debate-about-2050-pathways.html>about some other people's preferred pathways.</a>
</p>
<hr>
<p>
<b>The outcome</b> -
<a href=http://2050-calculator-tool.decc.gov.uk/pathway/p0h1221111p311110211112004324440333401102301340110241/primryenergychrt>Here is the pathway that we got to after one hour</a> - I will write a few notes and propose possible tweaks in a moment. Top things that needed doing: (a) check which fuel mix for the CCS power stations works best; (b) check which choice of fuel from bioenergy works best; (c) explore space-heating options - the audience asked for a 15:25:60 mix of fuel-in-home (eg gas boilers):district-heating:heat-pumps, and the "CD" heating mix doesn't match this perfectly.
Thank you to the audience for a fun evening!
<p>
<b>Update</b> -
After the lecture I made a few adjustments to the above pathway which I think the audience would have been content with. <a href=http://2050-calculator-tool.decc.gov.uk/pathways/p0h4221111p311110211122004324440333401102301410110241/primary_energy_chart>The resulting <b>final IET London pathway (March 2014)</b> is here</a>.
The changes I made were as follows: (a) I checked which choice of CCS power station fuel (solid/gas) was best for emissions, and selected "D". (b) I checked which "type of fuels from biomass" was best for emissions, and selected "B" (mainly solid). (c) I adjusted the commercial heating choice to "D,A" so as to make the overall heating mix for homes and commercial closer to the heating mix that the audience voted for. (d) I double-checked whether choices
(a, b) were still optimal. The resulting pathway achieves a <b>77%</b> reduction in emissions on 1990 levels (pretty close to the 2050 target of at least 80%), and requires <b>no backup generation</b> in mid-winter when the wind doesn't blow.
David MacKay FRShttp://www.blogger.com/profile/08023079754784119955noreply@blogger.com23tag:blogger.com,1999:blog-6156940350159100953.post-70593293437856776222013-12-11T23:57:00.002-08:002013-12-11T23:57:39.256-08:00Turboprop update, and a Hot Air Oscar nomination<div dir="ltr" style="text-align: left;" trbidi="on"><table>
<tr><td valign=top>
<img src="http://www.inference.eng.cam.ac.uk/sustainable/book/errata/ATR600/ATR600-33.png" alt="ATR600 - image from atraircraft.com" width="171" height="84" align=left>
My attention was recently drawn to an impressively fuel-efficient turboprop
aircraft, the
<a href=http://www.atraircraft.com/media/downloads/brochure%20ECO_light.pdf>ATR72-600</a>,
which is claimed to be about <em>one third</em> more energy efficient than
Bombardier's Q400 turboprop, which I featured on <a href=http://www.withouthotair.com/c5/page_35.shtml>page 35 of SEWTHA</a>.
</td></tr></table><br>
<table>
<tr><td valign=top>
<img src="http://www.inference.eng.cam.ac.uk/sustainable/book/errata/ATR600/HotAirOscar-ATR72.png" alt="HotAirOscar-ATR72" width="321" height="328">
</td>
<td valign=top>I've consequently
<a href=http://www.inference.eng.cam.ac.uk/sustainable/book/errata/turboprop.html>written an
update on turboprops</a>, celebrating this achievement,
but in the interests of balance I feel I should also
nominate the advertisers of the ATR72-600 for
this year's <b>Hot Air Oscar for the most misleading "green" infographic</b>,
for this astonishing picture [at left] showing the difference between
the fuel consumption of the ATR 72 and the Q400 on a 250-nautical-mile journey.
As the <em>numbers</em> in the picture show, the ATR 72's fuel consumption
is 70% of the Q400's, but the volume of the three-dimensional blue barrel shown
is
<b>30%</b> of the volume of the orange barrel — a
2.3-fold
exaggeration!
</td></tr>
<tr><td valign=top>
<table bgcolor=#ebebeb>
<tr bgcolor=ffffbb><td></td><td>blue barrel</td><td>:</td><td>orange barrel</td><td></td></tr>
<tr bgcolor=ffffdd><td>ratio of diameters</td><td>91</td><td>:</td><td>134</td><td>=0.68:1</td></tr>
<tr bgcolor=ffffdd><td>ratio of heights </td><td>118</td><td>:</td><td>179</td><td>=0.66:1</td></tr>
<tr bgcolor=#ffffbb><td colspan=4 rowspan=2>ratio of volumes <br> (as depicted) </td><td>=0.68×0.68×0.66</td></tr>
<tr bgcolor=#ffffbb><td>=<b>0.30:1</b></td></tr>
<tr bgcolor=#ffff99><td colspan=4>true ratio of volumes<br>(735:1043) </td><td>=<b>0.70:1</b></td></tr>
</td></tr></table></td></tr></table>
<br /></div>
David MacKay FRShttp://www.blogger.com/profile/08023079754784119955noreply@blogger.com1tag:blogger.com,1999:blog-6156940350159100953.post-8086872469711072272013-12-11T02:12:00.002-08:002013-12-11T02:12:59.028-08:00Do UK wind farms decline "very dramatically" with age?<div dir="ltr" style="text-align: left;" trbidi="on">
In December 2013, Christopher Booker <a href=http://www.telegraph.co.uk/earth/energy/windpower/10500929/Wind-turbines-policy-is-all-at-sea.html>in the Telegraph</a> discusses a study by Gordon Hughes, published by the Renewable Energy Foundation in December 2012, which is said to show, due to wear and tear on their mechanisms and blades, the amount of electricity generated by wind turbines "very dramatically falls over the years".
Booker asserts that "Hughes showed his research to David MacKay, the chief scientific adviser to the Department of Energy and Climate Change, who could not dispute his findings." <b>This is not true</b>.
<br>
In fact, I doubted Hughes's assertions from the moment I first read his study, since they were so grossly
at variance with the data.
<br>
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhrTetocrVgjM1jhcGi-b9i2p4ZTfFQJDTZEtO1lnlN_nhIPoSa2_PEc-S_N2K0xoGjj1BzTr9CMZxdmpVpr56OAjdX7EKOIrMSmaaNJd3s7qapGJ5WQoIqJNG-El8EmyWDP2BLTQb2-Sg5/s1600/LoadFactors10-15.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhrTetocrVgjM1jhcGi-b9i2p4ZTfFQJDTZEtO1lnlN_nhIPoSa2_PEc-S_N2K0xoGjj1BzTr9CMZxdmpVpr56OAjdX7EKOIrMSmaaNJd3s7qapGJ5WQoIqJNG-El8EmyWDP2BLTQb2-Sg5/s320/LoadFactors10-15.png" /></a></div>
<small><b>Figure 1:</b> Actual load factors of UK wind farms at ages 10, 11, and 15.
<br>a) Histogram of average annual load factors of wind farms at age 10 years. For
comparison, the blue vertical line indicates the assertion from the Renewable Energy
Foundation's study that "the normalised load factor is 15% at age 10."
<br>b) Histogram of average annual load factors of wind farms at age 11 years.
<br>c) Histogram of average annual load factors of wind farms at age 15 years. For
comparison, the red vertical line indicates the assertion from the Renewable Energy
Foundation's study that "the normalised load factor is 11% at age 15."
At all three ages shown above, the histogram of load factors has a mean and standard
deviation of 24% ± 7%.
</small>
<br>
Moreover, by January 2013 I had figured out an explanation of the underlying reason for
Hughes's spurious results. I immediately <a href=http://www.inference.eng.cam.ac.uk/mackay/abstracts/windDecline.html>wrote a technical report</a> about this flaw in Hughes's work, and sent it
to the Renewable Energy Foundation, recommending that they should retract the study.
<br>
I would like to emphasize that I believe the Renewable Energy Foundation
and Gordon Hughes have performed a valuable service by collating, visualizing, and making accessible
a large database containing the performance of wind farms.
This data, <em>when properly analysed in conjunction
with detailed wind data</em>, will allow the decline in performance of wind turbines to
be better understood. Iain Staffell and Richard Green, of Imperial College, have carried out
such an analysis (in press), and it indicates that the performance of windfarms <em>does</em> decline,
but at a much smaller rate than the "dramatic" rates claimed by Hughes. The evidence of decline is
strongest for the oldest windfarms, for which there is more data. For newer windfarms, the error bars on the decline rates are larger, but Staffell and Green's analysis indicates that the decline rates may be even smaller.
<br>
I will finish this post with a graphical explanation of the flaw that I identified
<a href=http://www.inference.eng.cam.ac.uk/mackay/abstracts/windDecline.html>(as described
in detail in my technical report)</a>
and that I believe underlies Hughes's spurious results.
<br>
The study by Hughes modelled a large number of energy-production measurements from 3000 onshore turbines, in terms of three parameterized functions: an
age-performance function "f(a)", which describes how the performance of a typical wind-farm declines with its age; a wind-farm-dependent parameter "u<sub>i</sub>" describing how each
windfarm compares to its peers; and a time-dependent parameter "v<sub>t</sub>" that captures national wind conditions as a function of time. The modelling method of Hughes is
based on an underlying statistical model that is <em>non-identifiable</em>: the underlying model
can fit the data in an infinite number of ways, by adjusting rising or falling trends in
two of the three parametric functions to compensate for any choice of rising or falling
trend in the third. Thus the underlying model could fit the data with a steeply dropping age-performance function, a steeply rising trend in national wind conditions,
and a steep downward trend in the effectiveness of wind farms as a function of their
commissioning date (three features seen in Hughes's fits). But all these trends are
arbitrary, in the sense that the same underlying model could fit the data exactly as
well, for example, by a less steep age-performance function, a flat trend (long-term)
in national wind conditions, and a flat trend in the effectiveness of wind farms as a
function of their commissioning date.
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgwH8MkkFypNLhg01IAk2-t5Gsq5JQGkTJ7qU4w_cqep4Eu0xYzPxtaEtMdR0IAzOmsnsbAscnwhSCkk1pfyYfEaq73j8OHc679pt7opet9eOEJs8f3VCRDA8h6ePns0qFzqHk23lYj9aPA/s1600/Anim.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgwH8MkkFypNLhg01IAk2-t5Gsq5JQGkTJ7qU4w_cqep4Eu0xYzPxtaEtMdR0IAzOmsnsbAscnwhSCkk1pfyYfEaq73j8OHc679pt7opet9eOEJs8f3VCRDA8h6ePns0qFzqHk23lYj9aPA/s1600/Anim.gif" /></a></div>
The animation above illustrates this non-identifiability. The truth, for a cartoon world, is shown on the left. On the bottom-left, the data from three farms (born in 87, 91, and 93) are shown in yellow, magenta, and grey; they are the sum of a age-dependent performance function f(a) [top left] and a wind variable v_t [middle left]. (The true site 'fixed effects 'variables u1, u2, u3 are all identical, for simplicity.) On the right, these identical data can be produced by adding the orange curve f(a) to the site-dependent 'fixed effects' variables u1, u2, u3 (shown in green), thus obtaining the orange curves shown bottom right, then adding the wind variable [middle right] shown in blue (v_t).
<br /></div>
David MacKay FRShttp://www.blogger.com/profile/08023079754784119955noreply@blogger.com4tag:blogger.com,1999:blog-6156940350159100953.post-58615786024488596952013-11-18T08:04:00.002-08:002013-11-18T08:39:25.513-08:00Enormous solar power stations <div dir="ltr" style="text-align: left;" trbidi="on">
Three spectacularly large solar power stations have recently been in the news:
<b>Ivanpah</b>, located in California, but within spitting distance of Las Vegas, is a concentrating solar power station in which 300,000 flat mirrors focus sunshine onto three power-towers.
<b>Solana</b>, located in Gila Bend, Arizona, has a collecting field of about 3200 parabolic-trough mirrors, each about 25 feet wide, 500 feet long and 10 feet high, and it can generate electricity at night thanks to its ability to store high-temperature heat in vast molten salt stores.
<b>Kagoshima</b>, near the Southern tip of Japan, has 290,000 solar photovoltaic panels.
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgsUTeG200htk1IP0h0s3BJ3sMnJ_9GVK7wJHK4XeKg3n-li7kGeX3qKU5OUhSstbLk0c7-kh4JkjH-jgnBElD9as-u1hTBBpTXxME9ejq44mfHdOTUYcKo3Tuwv-rKsu8jnOM6CgBCdSPj/s1600/IvanpahSolanaKagoshimaM.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgsUTeG200htk1IP0h0s3BJ3sMnJ_9GVK7wJHK4XeKg3n-li7kGeX3qKU5OUhSstbLk0c7-kh4JkjH-jgnBElD9as-u1hTBBpTXxME9ejq44mfHdOTUYcKo3Tuwv-rKsu8jnOM6CgBCdSPj/s1600/IvanpahSolanaKagoshimaM.png" /></a></div>
All three are enormous, and must be amazing to visit: Ivanpah occupies about 14 km<sup>2</sup>; Solana, 12.6 km<sup>2</sup>, and Kagoshima, 1 km<sup>2</sup>.
<p>
Now, I'm always interested in <em>powers per unit area</em> of energy-generating and energy-converting facilities,
so I worked out the average power per unit area of all three of these, using the estimated outputs
available on the internet. <b>Interestingly, <em>all three</em> power stations are expected to generate about 8.7 W/m<sup>2</sup></b>, on average.
This is at the low end of the range of powers per unit area of concentrating solar power stations that I
discussed in <a href=http://www.withouthotair.com/c25/page_184.shtml>Chapter 25</a> of <em><a href=http://www.withouthotair.com>Sustainable Energy - without the hot air</a></em>; Andasol, the older cousin of Solana in Spain, is expected to produce about 10 W/m<sup>2</sup>, for example.
<p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiSSLqt7mygP6f8Hgv7RfSv4UbsGzLa_bDmRwaX_X94oJ30PmYYU-HKeshOPsrVCFllLhvAdS_DMl_h0mI9HYjSl2yxLy0SBwi7KC75QsOfxCR8F_9F7zEtaRJEoWQJN6OCba-L0PlAFzxO/s1600/CanSolarDeliver.gif" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiSSLqt7mygP6f8Hgv7RfSv4UbsGzLa_bDmRwaX_X94oJ30PmYYU-HKeshOPsrVCFllLhvAdS_DMl_h0mI9HYjSl2yxLy0SBwi7KC75QsOfxCR8F_9F7zEtaRJEoWQJN6OCba-L0PlAFzxO/s1600/CanSolarDeliver.gif" /></a></div>
I published a paper on <a href=http://www.inference.phy.cam.ac.uk/sustainable/book/tex/RSsolar.html>
Solar energy in the context of energy use, energy transportation, and energy storage </a> in the <em>Phil Trans R Soc A</em> Journal earlier this year, and these three new data points lie firmly in the middle of the
other data that I showed in that paper's figure 8 (<a href=http://www.inference.phy.cam.ac.uk/sustainable/ppt/>original figures are available here</a>).
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjSByS-ONSKN_7mxlRvhqHCvBnmk1HL3O8HOPkW_iD0RxS-UgMjgdYtClHU_FhRxibhogZa9Zvw35-ex4OJISBHBcCPOcAl7I9QVdCrDPYLQbzSzn49cV5BaMqr3injbf0tDhKeyRjojwEF/s1600/PPAvInsol.png" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjSByS-ONSKN_7mxlRvhqHCvBnmk1HL3O8HOPkW_iD0RxS-UgMjgdYtClHU_FhRxibhogZa9Zvw35-ex4OJISBHBcCPOcAl7I9QVdCrDPYLQbzSzn49cV5BaMqr3injbf0tDhKeyRjojwEF/s640/PPAvInsol.png" /></a>.
<p>
These data should be useful to people who like to say "to power all of <em>(some region)</em> all we need
is a solar farm the size of <em>(so many football fields, or Greater Londons, or Waleses)</em>, if they
want to get their facts right.
For example, Softbank Corporation President Masayoshi Son recently alleged that <a href=http://inhabitat.com/japan-will-generate-electricity-by-turning-unused-rice-paddies-into-solar-farms/rice-paddy-solar-farm-2/><em>"turning just 20% of Japan’s unused rice paddies into solar farms would replace all 50 million kilowatts of energy generated by the Tokyo Electric Power Company"</em></a>. Unfortunately, this is wishful thinking, as it is wrong by a factor about 5. The area of
unused rice paddies is, according to Softbank, 1.3 million acres (a little more than 1% of the land area of Japan).
If 20% of that unused-rice-paddies area were to deliver 8.7 W/m<sup>2</sup> on average, the <em>average</em> output would be about 9 GW. To genuinely replace TEPCO, one would need to generate roughly five times as much electricity,
<em>and</em> one would have to deliver it when the consumers want it.
<p>
Maybe a better way to put it (rather than in terms of TEPCO) is in national terms or in personal terms:
to deliver Japan's total average electricity consumption (about 1000 TWh/y) would require 13,000 km<sup>2</sup> of solar power stations (3.4% of Japan's land area), and systems to match solar production to customer demand;
to deliver a Japanese person's average electricity consumption of 21 kWh per day, each person would need a 100 m<sup>2</sup> share of a solar farm (that's the land area, not the panel area or mirror area).
And, as always, don't forget that electricity is only about one third or one fifth
of <em>all</em> energy consumption (depending how you do the accounting). So if you want to get a country
like Japan or the UK off fossil fuels, you need to not only do something about the current electricity demand but also deal with transport, heating, and other industrial energy use.
<hr>
<small>Sources: <a href=http://www.nrel.gov/csp/solarpaces/project_detail.cfm/projectID=62>NREL</a>;
<a href=http://www.abengoa.com/web/en/noticias_y_publicaciones/noticias/historico/2013/10_octubre/abg_20131009.html>abengoa.com</a>;
<a href=http://www.nrel.gov/csp/solarpaces/project_detail.cfm/projectID=23>NREL</a>;
<a href=http://www.solarserver.com/solar-magazine/solar-news/current/2013/kw45/kyocera-puts-japans-largest-solar-pv-plant-online.html>solarserver.com</a>; and google planimeter.</small>
<br /></div>
David MacKay FRShttp://www.blogger.com/profile/08023079754784119955noreply@blogger.com10tag:blogger.com,1999:blog-6156940350159100953.post-56382268179098071282013-10-14T09:16:00.001-07:002013-10-14T09:18:01.420-07:00Chinese translation of Sustainable Energy - without the hot air <div class="separator" style="clear: both; text-align: center;"><a href=http://www.amazon.cn/%E5%9B%BE%E4%B9%A6/dp/B00FA4RILU><img border="1" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhUQLxyogtLOxzd3jhYo-TlXmsZFCSqf-8LEIzIPR9Kic3oL2_uRQZLIUIEqprO-Ek872IoQnl2rGNrr8cUFUlZe1T7LeSpC4BRjT4_6UbmD2EH7sSbYwZoRYJhplZxRaPSkmmETnyimm5Q/s320/ChineseCoverS.jpg" /></a></div><div dir="ltr" style="text-align: left;" trbidi="on">
The <a href=http://www.amazon.cn/%E5%9B%BE%E4%B9%A6/dp/B00FA4RILU>Chinese translation</a> of <a href=http://www.withouthotair.com>Sustainable Energy - without the hot air</a> is
<a href=http://www.amazon.cn/%E5%9B%BE%E4%B9%A6/dp/B00FA4RILU>now available on amazon.cn</a>
<br>
I am very grateful to the Chinese Academy of Sciences and President Li Jinhai for
arranging both the translation and its publication. Thank you!
<br /></div>
David MacKay FRShttp://www.blogger.com/profile/08023079754784119955noreply@blogger.com0tag:blogger.com,1999:blog-6156940350159100953.post-52463368489971374512013-06-09T12:18:00.002-07:002014-02-22T12:43:40.334-08:00David MacKay's "Map of the World" - an update<div dir="ltr" style="text-align: left;" trbidi="on">
<a href="http://www.inference.phy.cam.ac.uk/sustainable/data/powerd/MapOfWorld.html" imageanchor="1" ><img border="0" src="http://www.inference.phy.cam.ac.uk/sustainable/data/powerd/PPPersonVsPDen2WA.eps.png" /></a>
I've updated my
<a href=http://www.inference.phy.cam.ac.uk/sustainable/data/powerd/MapOfWorld.html>"Map of the World"</a>
which shows, country by country, how human power-consumption per unit area
compares with the power-production per unit area of renewables.
I originally published this graph <a href=http://withouthotair.blogspot.co.uk/2009/08/new-graph-showing-countries-power-per.html>on my blog
in August 2009</a>.
I've made quite a few improvements to it since then, including the representation of country size by point size,
and colour coding of continents in the style of Gapminder.
<br>
One interesting thing I figured out while working on this graph is that, while the
<b>average</b> power consumption per unit land area of the world is 0.1 W/m<sup>2</sup>,
<b>78% of the world's population</b> lives in countries where the
average power consumption per unit land area of the world is <b>greater than</b> 0.1 W/m<sup>2</sup> —
much as, in a town with
some crowded buses and many empty buses, the average number of passengers per bus
may be small, but the vast majority of passengers find themselves on crowded
buses.
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjKDqjziFG8_EsxpOIuVQN_nLTZpCKswXiaYLtbjk67AsJJsUgOhA9c8RRSscWjQLyfqE8hTjjb9fIlJcRxvYhx-9PYSs8EUr6EmbbCftJMJnNcaEnonKRsTO6B5WeUYA0KdZ1WKjheArOy/s1600/powerDensityHistogram.png" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjKDqjziFG8_EsxpOIuVQN_nLTZpCKswXiaYLtbjk67AsJJsUgOhA9c8RRSscWjQLyfqE8hTjjb9fIlJcRxvYhx-9PYSs8EUr6EmbbCftJMJnNcaEnonKRsTO6B5WeUYA0KdZ1WKjheArOy/s320/powerDensityHistogram.png" /></a>
<br>
Please follow
<a href=http://www.inference.phy.cam.ac.uk/sustainable/data/powerd/MapOfWorld.html>this "Map of the World"</a> link to see multiple versions of the graph, and to download high-resolution originals, which everyone is welcome to use.
<br>
My "Map of the World" graphs are published this year in two journal papers, which I will blog about shortly.
<center><font size=-2>
<table bgcolor=#ffffaa cellpadding=2 cellspacing=2>
<tr><td valign=top bgcolor=#ffffdd>
David J C MacKay (2013a) Could
energy-intensive industries be powered by
carbon-free electricity? Phil Trans R Soc A 371:
20110560.
http://dx.doi.org/10.1098/rsta.2011.0560
</td>
<td valign=top>This paper also contains detailed information about the power per unit area of wind farms in the UK and USA,
and of nuclear power facilities</td>
</tr>
<tr><td valign=top bgcolor=#ffffdd>
David J C MacKay (2013b) Solar
energy in the context of energy use, energy
transportation and energy storage. <em>Phil Trans
R Soc</em> A 371: 20110431.
http://dx.doi.org/10.1098/rsta.2011.0431
</td>
<td valign=top> This paper also contains detailed information about the power per unit area of solar farms </td>
</tr>
</table>
</font>
</center>
<br /></div>
David MacKay FRShttp://www.blogger.com/profile/08023079754784119955noreply@blogger.com7tag:blogger.com,1999:blog-6156940350159100953.post-48568049409903505012013-04-08T04:01:00.002-07:002013-04-08T11:24:58.889-07:00I've been unfair on Hydrogen<div dir="ltr" style="text-align: left;" trbidi="on">
In <a href=http://www.withouthotair.com/Contents.html><em>Sustainable Energy - without the hot air</em></a> I spent a couple of pages discussing
hydrogen transportation, under the title <a href=http://www.withouthotair.com/c20/page_129.shtml>"Hydrogen cars – blimp your ride"</a>.
While I still think that some people have been overhyping hydrogen
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiGSTdwAGd-zZ4XOdav65d5bg6SXZHiuiW-ZyW20WRnn5ACGtTi8ZHmQ-h5vvD5Gz9_jCX4Bzm10eSJFkGKwG6A551PyS57o8Jlyo5CN9mGqzWkd7mjMXtsp1NgjdYeBeTJZLk-JL-tcrp9/s1600/1122HummerArnoldINT_MN.jpg" imageanchor="1" ><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiGSTdwAGd-zZ4XOdav65d5bg6SXZHiuiW-ZyW20WRnn5ACGtTi8ZHmQ-h5vvD5Gz9_jCX4Bzm10eSJFkGKwG6A551PyS57o8Jlyo5CN9mGqzWkd7mjMXtsp1NgjdYeBeTJZLk-JL-tcrp9/s320/1122HummerArnoldINT_MN.jpg" /></a>
- even Nature magazine, who praised Governor Arnold for filling up
a hydrogen-powered Hummer -
<b>some of the criticisms I wrote were incorrect and I wish to correct them</b>.
<p>
On <a href=http://www.withouthotair.com/c20/page_131.shtml>page 131</a> I wrote:
<quote><em>... 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.</em></quote>
Both of these statements are incorrect.
</p>
<p>
First, while hydrogen is a very leaky little molecule,
it <em>is</em> 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 <em>is</em> an issue for
containers with non-metallic (polymer) liners (Type 4) which readily allow the
permeation of hydrogen. [Source:
<a href=http://conference.ing.unipi.it/ichs/images/stories/papers/232.pdf>P. Adams et al</a>]
</p>
<p>
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 <em>starts</em> 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 <em>5 days</em> and a mean autonomy time of <em>30 days</em>. 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 <em>heat</em> is permeating <em>in</em>, 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
<em>can</em> achieve both of these targets, so what I wrote was unfair on hydrogen vehicles.
[Source: EERE 2006 <a href=http://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/cryocomp_report.pdf>Cryo-Compressed Hydrogen Storage
for Vehicular Applications</a>]
</p>
<p>I apologise to the hydrogen community for these errors.
</p>
<p>
I will add a correction to the <a href=http://www.withouthotair.com/Errata.html>errata</a> imminently.
</p>
<br /></div>
David MacKay FRShttp://www.blogger.com/profile/08023079754784119955noreply@blogger.com3tag:blogger.com,1999:blog-6156940350159100953.post-59331717956119090322012-12-14T14:10:00.002-08:002012-12-14T14:10:26.446-08:00L'energie durable - pas que du vent!<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEht470Q6TKCD1gUvDep9V4Q2c1JOC2Ibk33L6oH0Wo8EcIAOsL6ijquohItg4rfo7yOugJXv-I-xjikcqX9O60SeTJRVHpDMvOed36LSt_A23YWJu-NuQBa52hriHIvVMbX1yLWDCUMZnbc/s1600/sewtha-fr-cov.png" imageanchor="1" style="margin-left:1em; margin-right:1em"><img border="0" height="320" width="230" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEht470Q6TKCD1gUvDep9V4Q2c1JOC2Ibk33L6oH0Wo8EcIAOsL6ijquohItg4rfo7yOugJXv-I-xjikcqX9O60SeTJRVHpDMvOed36LSt_A23YWJu-NuQBa52hriHIvVMbX1yLWDCUMZnbc/s320/sewtha-fr-cov.png" /></a></div>
<div dir="ltr" style="text-align: left;" trbidi="on">
On 13th December 2012, I helped launch the French translation of <em>Sustainable Energy - without the hot air</em> by giving a talk in Paris, hosted by the Ecole Normale Superieure and the kind volunteer translators, <a href=http://www.amides.fr>AMIDES</a>.
The book was featured today by <b>Le Figaro</b>:
<a href=http://bourse.lefigaro.fr/devises-matieres-premieres/actu-conseils/le-professeur-mackay-reduit-les-emissions-d-aneries-326764>
Le Professeur MacKay réduit «les émissions d'âneries»
</a>.
<br>
Just like the original <a href=http://www.withouthotair.com/>English book</a>,
the French translation is available <a href=http://www.amides.fr>free on-line</a>,
and it can be bought at a reasonable price from your favourite retailers.
<ul>
<li><a href=http://www.amazon.co.uk/dp/2804168956/tag=davidmackay0f-21><b>amazon uk</b></a>,</li>
<li><a href=http://www.amazon.fr/L%C3%A9nergie-durable-Pas-seulement-vent/dp/2804168956/>amazon.fr</a>,</li>
<li><a href=http://livre.fnac.com/a3832728/David-Mackay-Energie-durable-pas-seulement-du-vent>fnac</a>.</li></ul>
<br /></div>
David MacKay FRShttp://www.blogger.com/profile/08023079754784119955noreply@blogger.com0