Friday, January 26, 2007

No Sense to a Hydrogen Economy.

This is the conclusion of Ulf Bossel in a recent paper published in the Proceedings of the IEEE (2006, Vol. 94, page 1826). Bossel is with the European Cell Forum, based in Switzerland, and has spoken out previously and convincingly on the topic of "hydrogen", pointing out the energy and economic deficiencies of the putative "hydrogen economy". As he stresses, the establishment of a sustainable energy future is one of the most pressing tasks for mankind. As fossil fuel resources begin to run-out, he predicts that the energy economy will change from a chemical to an electrical base. However, to make this transition is not simply an act of political will, but the underlying science to do so must be sound, and be based on proven technology and existing engineering experience - not pie in the sky proposals! The process (the ride down the rough side of the failing oil production Peak) will take many years and of course it must start as soon as possible, while we still have existing resources in reasonable plenty to utilise in the fabrication of new technology. A secure sustainable energy future cannot be based on hype and activism, but has to be built on solid established foundations of known science and engineering. Bossel (as usual) makes a quantitative analysis of what is involved and concludes that only 20%-25% of the source energy needed to synthesized hydrogen from natural compounds (e.g. methane from natural gas) can be ultimately recovered by efficient fuel cells. This is not good. In my posting on Monday "Hydrogen for Oil?", I settled for a figure of around 35%, which appears rather optimistic in the light of Bossel's analysis. It might appear then, that anywhere up to a doubling of the number of wind turbines and nuclear power stations that I reckoned (32,000 2 MW turbines or 21 Sizewell B type 1.2 GW nuclear power plants) would be needed to make enough hydrogen to supplant the amount of fuel currently used to run the nation's road transport fleet. As an energy carrier, hydrogen cannot compete with electricity (electrons). To quote Bossel: "As the fundamental laws of physics cannot be chanced by research, politics or investments, a hydrogen economy will never make sense."

Along with all the problems of storing hydrogen, which needs high pressures and cryogenic cooling, even if it is adsorbed in porous materials like zeolites (none of which have met the storage capacity criteria demanded for them; last posting here "Hydrogen Storage in Zeolites"), and the fact that it makes some metals brittle over time and hence leaky (NOT good for an explosive gas), it might be better to store the electrons in "batteries" to get a better overall efficiency of 50% than 20-25% for hydrogen, when we could get away with around 20,000 2 MW or 8,000 5 MW turbines. That same job could be done using another 13 nuclear power plants, to be built on top of the 30 or so that will already be needed by 2025, to replace the current generation of them.

If we were to localise our society and cut transport by 90% we would be down to just 10% of this, needing only 2000 2 MW or 800 5 MW turbines. There would be no planes though, and if we want to keep them flying some other means must be found to do so.

Using energy in the form of electrons means that the existing electricity distribution infrastructure could be adapted, rather than introducing a wholesale entirely new hydrogen storage and distribution network on a gargantuan scale.

Neither biofuels nor biohydrogen can meet the huge present demand for transportation fuels either, and would vastly exceed all available arable land for food production even to provide 10% of what is currently used to run cars and road transport in general. However, along with electricity, biofuels could satisfy much of the energy needs of localised economies.


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