Hydrogen Hurdles

Regular readers of this blog know that I'm no fan of hydrogen-powered internal combustion engine cars. BMW is the leading proponent of this strategy, the flaws of which I described recently. That's not why you should read this road test of BMW's latest hydrogen-capable 7-Series sedan in MIT's Technology Review. Rather, it's a great illustration of the many hurdles that remain before any hydrogen car, whether ICE or fuel-cell based, can be truly practical and suitable for the mass market. Echoing the sentiment of the reporter, I wish that weren't so, but it is. This reality shatters some predictions I made eight years ago.

In the late 1990s, Texaco undertook its first corporate-level scenario planning effort, and one of the key findings--along with the growing importance of climate change as an issue--was the possibility of major changes in transportation energy systems. Fuel cells were front and center in this view of the future, and with them the prospect of an emerging hydrogen economy. No one involved in the project was naive enough to think this could all happen overnight, but there were good reasons to believe that by the middle of the current decade, hydrogen-powered cars could be available to ordinary consumers, who would be attracted by their combination of environmental benefits and novel technology. I expounded that view to Texaco's top management and in sessions with employees at all levels. What happened?

Well, as the TR piece reveals, hydrogen is a tricky beast, a tiny molecule that behaves quite differently than the much larger fuel molecules we're used to handling: methane, propane, or the molecular soup found in a gallon of gasoline. H2 is expensive to make, inefficient to store, and elusive enough to escape from any ordinary fuel system. When my colleagues and I looked at this in the '90s, there were two obvious ways around the storage problem. One involved making the H2 onboard the vehicle out of something easier to handle, such as gasoline or methanol, and never storing it at all. The alternative was storing it chemically, rather than mechanically, through adsorption in a solid metal-hydride material. Texaco funded research on the former path and bought a share of a company with the key technology for the latter, at least partly on the strength of the vision laid out by my team.

Both of these paths are still possible, though you don't hear as much about onboard H2 production or "reforming," because it still entails vehicle exhaust other than water, and it's nice to be able to claim a car is "zero emission"--even if there are lots of emissions upstream of it. Without getting into the technical details, however, neither of these paths is quite ready to compete with cars that use the utterly reliable petroleum products value chain. Frankly, although it's workable today, the liquid hydrogen storage mode chosen by BMW is ludicrously bad. Would you buy a gasoline car if half the fuel evaporated every week and you couldn't park it in an enclosed place? That's what you get with cryogenic H2 storage. You might just as well burn dollar bills. Compressing the H2 to 10,000 psi isn't much better, in terms of the energy cost involved and the perceived safety. And those are the best two options for hydrogen today, in terms of technology readiness.

You would be right to think that my experience with this has made me less sanguine about the inevitability of a hydrogen economy, or the rapid adoption of any radically different transportation energy system. That's not because I'm embarrassed about having made some aggressive predictions that didn't pan out, but because I've learned something from it. Every system has an inherent lag time, and the general public's model of technology change has been overly influenced by the electronics industry. Even there, we've ignored all the years that products like VCRs and cellphones spent in the laboratory and in field trials. Hybrid cars have avoided this trap and done at least as well--so far--as I expected in 1997, because of their compatibility with existing infrastructure, which appears to be the "rate-limiting step" for alternative fuel vehicles. That has implications for the success of biofuels, too.