Last week, Erik Hoffner posted about H2CAR, a process developed at Purdue University that would allegedly dramatically improve the productivity of coal or biomass gasification by adding hydrogen to the mix.

I was intrigued by the idea, and read the article. Unfortunately, I think this is a dead end.

No beating around the bush — the killer aspect of the plan is the huge amounts of hydrogen that would be created. The smallest amount cited by the paper is approximately 150 billion kg of H2 a year, in a scenario where Americans all drive plug-in hybrids.

The concept rests on all this H2 being produced by renewable water electrolysis, which would be carbon-neutral. The problem is that it takes an enormous amount of electricity (in the area of 50 kilowatt-hours) to make a single kilogram of hydrogen. This means than — in the most optimistic scenario they can imagine — the U.S. would need to install two and a half times its current electrical generating capacity, all renewables or carbon-free, and devote it solely to producing hydrogen fuels.

Not only is this probably never going to happen on cost grounds alone, but it would be stupidly wasteful. If we had the kind of renewable energy this concept requires, we could move everyone around in electric cars and trains far more efficiently, with surplus left over to, I don’t know, retire all of our coal and gas plants immediately.

It’s really kind of weird to read the paper. First, assume we have several multiples more renewable energy than we do. Then — once you’ve entered this fantasy land of total conjecture — think of the pettiest little task you can imagine doing. Me, if I had 10 terawatt-hours of renewable electricity to play with every year, I’d desalinate the Atlantic and irrigate the Sahara or something. Putting gasoline in people’s SUVs seems so … small-minded.

(Engineer-Poet at The Oil Drum read the same paper and is, if anything, less charitably inclined than I am. Plus, he did more math.)