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Jo, your arithmetic does not look quite right. Let's say that 90% abatement really does take 25% of power output, and it goes pro rata, then 7% of output will be needed for 25%. However new coal can go to 45% efficient. So using the same system as I did below, which is as far as I am aware correct, we have 45 x .93 / 100 x .75 = 42/75 = 56%. In other words it is carbon efficient as a coal fired station running at 56% thermal efficiency, which is way better than the 45% we started off with. However my arithmetic was also wrong in my questioning of Monbiot's figures because I forgot to include the greater carbon intensity of coal vs methane. This is going to tilt the balance well in favour of gas, as he correctly says. For coal to get as carbon efficient as gas, we need way more than the 25% CCS that is on the table. But how much? Heat value of coal is approx 35MJ/kg, heat value of gas is 55MJ/kg. Say coal is 90% C, methane 12/16 = 75% C by weight, then carbon:energy ratio of coal:methane is 35/9:55/75 = 3.9:7.3 = 0.53. In other words coal is produces about half as much heat per unit carbon as gas. So for coal fired electricity to have the same carbon footprint as gas, we need to be operating coal plant at an effective carbon-adjusted thermal efficiency of 75%. How feasible is this? Let's look at what may be the best we can get from CCS - 90% capture for a 25% overhead. Then we get 45 x .75 / 100 x .1 = 34/10 = 340% improvement of standard coal. Adjust that for thermal content of gas vs coal and it is still 1.7 times better than gas. But if we only get say 75% capture for 20% overhead we get 45 x .8 / 100 x .25 = 144%, equivalent to burning gas at 72% eficiency - so still an improvement. And if 50% capture for 15% overhead we get only 76%, still not good enough to compete with gas in carbon intensity. the message of all this is that 25% capture is simply not enough, not indeed is 50% capture. For coal to compete with gas in carbon intensity on equal terms we actually need to be getting more like 60% sequestration for a 15% overhead. How should the environmental community to respond? One simple demand should be that new coal should have enough CCS to now achieve the same carbon intensity as new non-CCS gas, which would probably be about 60% capture. By 2025 both coal and gas should be doing considerably better, with 90% capture on both coal and gas fired plant. Oliver Tickell. -----Original Message----- From: Discussion list for the Crisis Forum [mailto:[log in to unmask]] On Behalf Of jo abbess Sent: 24 April 2009 13:03 To: [log in to unmask] Subject: Someone's got to show me wrong on my arithmetic Hi Oliver and CRISIS FORUM, A commitment to 25% emissions abatement from coal-fired power generation is basically two commitments : using coal more efficiently, and doing some Carbon Capture and Storage. Using coal more efficiently will come about naturally building modern plant. It won't cost that much more. CCS on the other hand is very expensive. You're not going to get much CCS in a plant which only has a commitment to have 25% efficiency gains over conventional plant. It's all very well hearing arguments about "efficiency", but I need to hear the probable story about emissions too. It's all very well doing more with less fuel, but if the total amount of emissions rises, then no gain has been made. Here's my initial unproven calculation. Show me what's wrong with my thinking :- http://www.joabbess.com/2009/04/23/carbon-capture-and-storage-how-much-would / I'm not cheering about CCS. There's no such thing as "clean" coal. jo. +44 77 17 22 13 96 http://www.joabbess.com http://www.changecollege.org.uk ---------------------------------------- > Date: Fri, 24 Apr 2009 11:32:30 +0100 > From: [log in to unmask] > Subject: Re: Guardian climate summit > To: [log in to unmask] > > The article is written by John Vidal who is nobody's stooge. > > I might add I agree with it. It looks to me like the efforts of > Climate Camp, Greenpeace, Jim Hansen etc have paid off in that all > these new coal power stations will have CCS 25% for now, 100% (this > quoted figure is probably unfeasible, more like 80% possible) by 2025. > This is astonishingly close to what was being demanded. > > Of course we still want to know who will pay for it, and how. But > subject to this and a few other caveats, it looks like a green victory > that we should be celebrating! > > Just to prove the G is not beholden to EON we also have Monbiot taking > the opposite view: > http://www.guardian.co.uk/environment/georgemonbiot/2009/apr/23/carbon > -captu > re-and-storage-coal > > He seems to get something wrong here btw where he says that "These > partly abated coal plants, in other words, would still be much worse > than unabated gas plants." > > If we assume new coal is 40% efficient, then you get 40We (watts > electricity) for every 100Wc (watts coal). If 10% of power output goes > to power 80% CCS, then say 2.5% output for 25% CCS. So we are getting > approx 39We for the emissions from 100Wc - 25% = 75Wc. This is > equivalent in carbon terms to 39/75 = 52% efficiency - which is > comparable to typical CCGT of 50% efficiency. The effect of this is > thus to make coal as clean in carbon terms as gas. > > Of course there are no firm long term guarantees as to what will > happen across Parliaments and Governments. But that goes for anything. > > Oliver Tickell > www.kyoto2.org > > -----Original Message----- > From: Discussion list for the Crisis Forum > [mailto:[log in to unmask]] On Behalf Of Chris > Sent: 24 April 2009 10:37 > To: [log in to unmask] > Subject: Re: Guardian climate summit > > I wonder if the E.On sponsorship explains the Guardian's > interpretation of Milliband's announcements on coal fired power > stations as a victory for the environmentalists > > http://www.guardian.co.uk/environment/2009/apr/23/clean-coal-energy-po > licy > > Chris > > > > > ----- Original Message ----- > From: "jo abbess" > To: > Sent: Friday, April 24, 2009 9:23 AM > Subject: Re: Guardian climate summit > > > Hi CRISIS FORUM, > > The Guardian are such cowards. > > All the advertisements I've seen so far mentioned the FDF Food and > Drinks Federation, but not E.On. > > As you rightly point out, their website admits E.On are sponsoring it, > just like they did last year. > > Talk about totally subverting the social agenda...Talk about "coal > salers", or even "Climate Destroyers" :- > > http://science.blogdig.net/archives/articles/April2009/18/Guardian_Cli > mate_S ummit_2008__Climate_Destroyer_as_Major_Sponsor.html > > http://climatechangeaction.blogspot.com/2009/04/guardian-hypocrisy.htm > l > > jo. > +44 77 17 22 13 96 > http://www.joabbess.com > http://www.changecollege.org.uk > > > > > > > ________________________________ >> Date: Thu, 23 Apr 2009 21:39:03 +0100 >> From: [log in to unmask] >> Subject: Guardian climate summit >> To: [log in to unmask] >> >> >> >> >> >> >> >> >> >> >> just fyi..... (sponsored by e.on and the food and drink >> federation.....!) >> >> >> >> http://www.guardian.co.uk/climatesummit > > _________________________________________________________________ > View your Twitter and Flickr updates from one place - Learn more! > http://clk.atdmt.com/UKM/go/137984870/direct/01/= _________________________________________________________________ Share your photos with Windows Live Photos - Free. http://clk.atdmt.com/UKM/go/134665338/direct/01/