A very interesting shift has occurred in the last year or so, as energy prices climbed higher. Hydrogen, which was once seen as the nearly certain long-term solution for our energy needs, has gradually been displaced, at least in the public eye, by biofuels, particularly ethanol and biodiesel. Some of this is quite sensible; we are much closer to the point at which biofuels can have a meaningful impact on energy security and the environment, while hydrogen's potential is much longer-term. To the degree that enthusiasm for the former cuts off funding for research on the latter, however, we could be shortchanging our future economic growth.
Part of the new skepticism towards hydrogen is merely a function of greater familiarity. When it emerged in the 1990s as a serious possibility, largely as a result of the development of the Proton Exchange Membrane fuel cell, many of us failed to appreciate all the hurdles of technology and infrastructure development that would have to be surmounted. I recall predicting in the late 1990s that fuel cell cars would be mass-market within a decade. That now looks wildly optimistic. The sophistication of the media increased rapidly as well. The widespread recognition of hydrogen's role as an energy carrier, instead of a new energy source, occurred much faster than I expected.
But at the same time that this new realism arrived, it was permeated by pessimism that hydrogen could ever matter in our lifetimes. Articles such as this one from MIT's Technology Review, suggesting that practical hydrogen cars are 50 years away and arguing for greater efforts on hybrids and other near-term solutions, have become commonplace. At the heart of all of this is a phenomenon common to most radical technology changes: the S-curve. Simply put, the rate of change and adoption for a significantly different new technology proceeds gradually at first, gaining momentum almost imperceptibly, until it reaches a key transition point, at which it accelerates dramatically, with the slope of the curve going almost vertical for a time. Then it slows down again as it becomes mass market and improvements go back to being incremental. The automobile and personal computer followed similar paths, and hydrogen may, as well.
There are important reasons not to lose confidence in hydrogen's potential, at least until we discover truly insurmountable--rather than merely expensive and difficult--obstacles to its implementation. First, the ultimate growth of a hydrogen energy economy is essentially unlimited, because it doesn't rely on a single source of primary energy or eventually compete with food crops for arable land. Because it is only an energy distribution system, it would be as useful for handling hydrogen derived from natural gas as it would be for hydrogen sourced from nuclear fusion or orbital solar power stations. In addition, along with electricity, it shifts the entire environmental impact of the energy chain to its source, allowing greenhouse gas emissions to be captured where they are dense and concentrated, rather than diffuse and widely dispersed among end-uses.
I understand the temptation to shift research priorities away from hydrogen, in favor of technologies that can alter our near-term energy balance. We have genuine and serious problems today with an overstretched natural gas industry and in our reliance for crude oil imports on politically unreliable suppliers. But precisely because there are good options that can help with these problems, within a decade or so, most of them don't need the same level of basic R&D support that hydrogen does. $70 oil, if it persists the way the market expects, will pull biofuels and synthetic liquids fuels from gas and coal and into the marketplace. We're already seeing major energy companies investing in cellulosic ethanol and biodiesel. But slowing down hydrogen to pay for any of these would be equivalent to eating the seed corn. We will need all of these solutions--short-, medium-, and long-term--if we are to make a successful transition beyond the petroleum that made our entire society possible.