Wednesday, January 19, 2005


More On Hydrogen Power

Andrew Olmsted has a post on the merits of hydrogen-fueled cars. His main objections seem to be the lack of a "free" source of hydrogen, and the cost of infrastructure.

When it comes to a source of hydrogen fuel, it's obvious that it doesn't ocur naturally, and thus can only be considered as a storage and transportation media. But as such, we can use large power plants, which are far more efficient than small internal-combustion engines, to generate hydrogen. A modern coal-fired power plant runs at 42-45% efficiency, and electrolysis of hydrogen is theoretically about 92% efficient but more likely to be 80% at best. A gasoline internal-combustion engine can reach 32% efficiency (better with alcohol), but most of the figures I've seen are in the mid-20s, and considerably worse at part-throttle conditions (not to mention that they're essentially 0% efficient at idle). Fuel cells sit somewhere between the 40% value quoted by pessimists, and the 83% theoretical upper value. That places hydrogen via electrolysis at about 60% worse efficiency on the lower end, and perhaps 15% better on the upper end (yea, that's quite the range). We haven't factored in transportation and storage costs, or drivetrain efficiency; I suspect that a hub-motor electric design is far more efficient than a traditional drivetrain, but that's probably offset by the costs require to compress or liquify hydrogen.

More significantly, however, the US is far better positioned to produce coal than oil, and has abudant natural resources that provide a lot of opportunities for renewable energy generation. Current projections show significantly greater reserves for coal than oil, although I don't know what usage rate was assumed for each resource. Coal isn't easily processed in an IC engine in its raw form, but hydrogen electrolysis provides a means for its usage in personal transportation (even if fuel cells don't pan out, we can still use that hydrogen in internal combustion engines). Better yet is a scheme where electricity is generated via renewable resources, so hopefully coal may only provide the gateway between oil and wind or solar or hydro or whatever.

As far as infrastructure goes, no doubt it'll take a lot to make hydrogen energy transport into a reality. But this seems like a weak argument if one accepts that oil has a finite life as an energy source. So what if we've got a well-established petroleum infrastructure, if the resource disappears some years down the road? Interesting to me is the lack of investment in new petroleum infrastructure (especially gasoline refineries). That seems to indicate that Big Oil already considers this to be a dead-end path.

Andrew does link to a pretty cool site from Hydrogen Solar LTD, which is a company based in the UK that's developing a variety of hydrogen-via-solar technologies. Its Tandem Cell concept seems exactly like what I want on the roof of my home, as soon as it's practical. Energy independence would be a marvelous thing and would rank with the all-time greatest achievements of mankind.

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