Over the weekend I was catching up on articles, and one from Technology Review last week caught my attention. It was a brief interview with the new Secretary of Energy, Dr. Chu, covering nuclear power and fuel cells. In the back half, Secretary Chu explained why the DOE has cut funding for fuel cell R&D, suggesting that fuel cell cars were always a long shot, because they required "four miracles" to happen. Although I haven't mentioned fuel cells very frequently here in the last few years, I must say it's hard for me to consider the commercialization of something that I've already driven as requiring quite so many miracles as that. At the same time, I don't trivialize the obstacles that explain why fuel cell cars are still not available in large numbers, despite previous expectations--including my own--that they would be by now.
Dr. Chu helpfully breaks down the challenges facing fuel cells into four categories. Start with his concern about the principal source of hydrogen (H2) today, via extraction from natural gas. This route certainly undermines the "zero emissions" claim often attached to fuel cells. In practice, that means zero tailpipe emissions, but hardly zero emissions overall. Still, it's worth considering what else we could do with the natural gas in question. We could compress it and burn it in a modified internal combustion engine (ICE). T. Boone Pickens is quite fond of that idea, and it's not as foolish as some suggest, since it can displace a lot of petroleum and reduce emissions by 15-20% compared to a conventional car, on a well-to-wheels lifecycle basis. We could also use the Fischer-Tropsch process to convert natural gas to top-quality synthetic diesel at a somewhat smaller emissions savings, because the higher efficiency of a diesel engine is largely offset by the energy lost in fuel synthesis. Or we could produce H2, which as Dr. Chu notes involves throwing away about a third of the original energy in the gas by the time we've compressed the resulting H2. Yet the latter is the only one of these pathways that, despite the high energy price paid in producing H2, affords the opportunity to cut our overall lifecycle vehicle emissions in half, because producing electricity in a fuel cell is inherently so much more efficient than burning a fuel in an internal combustion engine. It's not perfect, but it's far from awful--unless you put the H2 into an ICE--and no miracles at all are required to make the H2.
Miracle number two involves H2 storage, and this looks a bit tougher. I am not keen on carrying around compressed gases at 5,000 or 10,000 psi in the same vehicle with my family, and that is no irrational fear. In my refinery days I saw examples of how much mechanical energy even 2,000 psi held, and I will never trust a Kevlar-wrapped tank enough to be fully comfortable with this option. Moreover, I don't think Dr. Chu is entirely correct that "compressed hydrogen is the best mechanism." ECD, a company that my former employer once invested in, has a technology for storing H2 via chemical absorption in metal hydrides, and you can buy canisters that use their technology today. The advantage of this system is that it doesn't involve high pressure. The disadvantage is that these hydrides are heavy, a drawback shared by the nickel-metal-hydride batteries (same basic technology) used in the Toyota Prius and other non-plug-in hybrids. None of these systems yet stores energy at the equivalent density (and thus driving range) of gasoline, but then neither do Lithium-ion batteries.
The third challenge concerns distribution, and this is a doozy. Transporting H2 in tube-trailers is fine for servicing demonstration refueling stations, but can't be scaled up to handle millions of cars. That may not be necessary, because the "reformers" that extract H2 from natural gas can be built on a scale that fits into a service station dispenser, drawing feedstock from local gas lines and delivering fuel without any need to transport it as H2, other than in the car. Installing such devices in thousands of locations would be a massive undertaking, but frankly the same can be said for the goal of installing E85 pumps at 10% of service stations, compared to about 2000 today. To me, cost-effective H2 distribution is a matter of engineering and economics, not scientific breakthroughs.
That leaves us with the one item on Dr. Chu's list that might qualify as requiring a genuine miracle: bringing the cost of a fuel cell stack down to a level comparable to an internal combustion engine, or at least to a point not so much more expensive as to render a fuel cell car inherently unaffordable. Fuel cells still cost over $1,000/kW--implying that just the fuel cell stack for a real car would cost more than an entire luxury car today. Forecasts that this would fall to anywhere near the roughly $35/kW of today's car engines remain theoretical, relying mostly on learning-curve effects analogized from other industries. Given the current state of the car industry, manufacturers will struggle enough just absorbing the initial high cost of low-volume plug-in hybrid car production, without taking on tens of thousands of dollars in losses per car for vehicles like the Honda FCX Clarity. Absent a breakthrough, an investment like that might truly require a miracle.
Whether making fuel cell cars a practical reality requires four miracles or only one, I have to agree with Dr. Chu's conclusion that their commercialization looks neither imminent nor assured. It's important to recall that hydrogen is merely another energy carrier, like electricity, rather than an energy source like petroleum or biofuels. The smart money today is on battery-electric cars, including plug-in hybrids. In order to beat them an automotive fuel cell stack must cost less than the battery pack required to give drivers the 250-300 mile range they seem to want, because in every other respect that matters a fuel cell vehicle is an electric car. However, we must keep in mind that the smart money is not always right. Cutting back federal R&D on fuel cells to a level that puts a higher priority on other options that can deliver meaningful results sooner seems prudent, as long as we don't abandon this option entirely, or cede our competitive position to others.