September 11th 2009. Join the Group Read. Chapter 23. Can King Coal be cleaned?
Listen to the interview with David MacKay on Today
(Instructions on how to join are at the bottom of the original post)
Should we adopt the Ise Shrine notion of sustainability? No - the issue is really about costly irreversible action, not keeping doing what we do for a very, very long time.
Clean coal will probably reduce the efficiency of the coal to electrical eneergy conversion process by about 1/3 -- from almost 40% to about 25%. Cleaning coal uses up coal at a greater rate. But if it does so in a climate-friendly way, why not?
Quite. But David's MacKay's concern is not entirely about environmental friendliness -- he is asking the question of whether the UK can keep living more or less as it is within its own energy budget. The logic of this is to say: "if we control what we can most easily control---our own lifestyles---and we can live within our energy and climate-asset budgets ... and if all other nations can, then that's a sufficient condition for having cracked the problem." (Economists keen on trade and exploiting comparative advantage would say it is not a necessary condition -- maybe we can do so even better by being less autarkic...).
David adopts an avowedly arbitrary definition of a sustainable burn rate: can a burn-rate be sustained for 1000 years? If yes, it is sustainable. That definition allows him to relate the UK's coal reserves with a daily per person sustainable consumption rate --- there would be less than 1 kWh of electricity per person available from clean coal. But we consume 180 kWh/day/person, so clean coal is a stop gap --- it will not see our way of life go on for that long.
This relies pretty crucially on the definition of sustainability, which I think is wrong for the purpose. David adopts what one might call the Ise Shrine notion of sustainability. The Ise Shrine was first built in 4BC and has been rebuilt, identically, ever since then every 20 years. It was last rebuilt in 1993. This is "sustainability" as in keeping on and on doing the same thing. David is ISe-esque in choosing our ability to do the same thing - burn British coal - for a very long time to come.
But the concept that really bites in "unsustainable" development, I think, are processes that do irreparable damage, not processes that cannot conceivably continue for a very long time. So if we had clean coal, we could deplete UK reserves in 100 years rather than 1000 and spend that time developing other solutions and infrastructure. There is nothing fundamentally unsustainable in that approach. At 10 times the depletion rate David suggests, clean-coal generated electricity could satisfy at tenth and a twentieth of our daily energy needs, which is not to be sniffed at.
So while David is right that this is a stop-gap, sustainability should not throw out the right stop-gaps.
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(David revives Jevons' very interesting 1865 forecast of the decline of British power based on the depletion of coal reserves. Ian Jack reviews Andy Beckett's history of the 70s in the LRB and reminds us of the pessimism that surrounded just the nadir that Jevons had forecast. North Sea oil, of course, was not in Jevons' forecast ....)
Comments
Tony Price is inaccurate when he says that using clean coal technologies will reduce the [thermal] efficiencies from 40% to 25%.
One of the primary aims of developing new technologies - particularly clean coal technologies - is to increase the thermal efficiencies, extracting more useful energy per tonne of coal.
The latest generation of Super/Ultra Critical Power Plants that are currently being developed and installed in several countries - including China - can operate at effiencies of 45% or higher. The goal is to build these plants [which operate at higher temperatures and pressures than older plant] with thermal efficiencies of 50% or higher. Installing carbon capture and storage will reduce the overall efficiencies of any fossil fuel plant - but a range of new technologies and options are available that can ensure 90% or more of the carbon dioxide can be captured and sequestrated.
Other technologies, such as Integrated Gasification and Combined Cycle technologies are also been developed which have higher thermal efficiencies, pluis allow carbon dioxide to be removed from the gas stream prior to combustion - and can also allow the production of hydrogen and other products.
I am afraid it is Andrew Cox who seems to confuse the issues. Yes, advanced coal technologies could increase thermal efficiencies compared to old-fashioned coal plant (where 35% energy efficiency was considered rather good). 40% was being quite generous as an average efficiency for coal plant. Combined cycle natural gas plant have achieved much greater efficiencies, and coal gasification may help .... but the conversion is itself energy intensive. So the total energy efficiency of the process will not be in the high 50%'s as achieved in natural gas CCGT technology.
The reduction from 40% to 25% was entirely for the capture technology. This is an estimate, since no systems are currently operating at scale. The energy has to be used to extract the CO2 from the flue gas and pump it elsewhere.
The 90% figure mentioned by AC is simply irrelevant to this question: he is stating how much carbon could be captured, not the efficiency at which it could be captured.
The reduction in efficiency of about 1/3 is the assumption that David MacKay makes. AC has produced no argument against this assumption in his post. I would be most interested to have the basis for his assertion made explicit.
tony
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