Thursday, March 06, 2008

When Electrons Beat Molecules

Yesterday I nearly missed a very significant piece of news--a signpost of the future, if you will--because it was buried in the B section of the Wall Street Journal. In an article entitled, "GM, Toyota Doubtful on Fuel Cells' Mass Use" the reporters cited comments at the Geneva Auto Show by executives of these two companies, suggesting that battery technology was improving faster than fuel cell technology and that the mass-marketing of the latter might be delayed for years. In light of the substantial investments that both companies have made in both technologies, these remarks reflect an important shift in the battle for future transportation energy market share between electrons and molecules. Better batteries would not just delay fuel cell vehicles; they might trump them altogether.

For over a century, the competition for powering automobiles has pitted the onboard conversion of chemical energy into kinetic energy against externally-generated electricity from a variety of sources that could be stored onboard and used on demand. Although the latter pathway generally consumes less total energy and results in fewer emissions, the "molecules" side has consistently won this tug-of-war, for two reasons. First, it mirrors our sources of primary energy, for which fossil fuels still contribute 85% of the total. More importantly, even after throwing away most of that chemical energy in the form of waste heat from inefficient internal combustion engines, these fuels still delivered a multiple of the amount of energy that could be stored in a battery pack of comparable size and weight. However, both of these considerations are now changing.

For decades researchers have worked to develop batteries that could store as much useful energy as chemical fuels and be recharged as quickly as a gasoline tank can be filled, performing this charge/discharge cycle a few thousand times without degrading noticeably. Fuel cells were seen as a clever way to finesse the lack of such a battery, by combining the energy storage densities of chemical fuels with a very efficient way to make electricity onboard. Hybrids and plug-in hybrids (PHEVs) represent another attempt to gain electrical efficiencies in spite of the deficiencies of existing batteries. The suggestion by GM's Mr. Lutz that lithium-ion batteries might soon give battery cars a 300-mile all-electric range calls into question not only the necessity of fuel cells, but of hybrids of all types and even the conventionally-powered car. Could electrons finally be poised to win the war, after a century of losing all the battles?

At the same time, the advent of modest but rapidly-growing quantities of electricity from cyclical or intermittent renewable sources not only begins to shift the fuel vs. electricity balance of our primary energy sources, but it also provides incentives for creating the means of storing renewable electricity when it is excess to the needs of the normal grid load or fluctuating strongly, a situation that has already caused isolated problems of grid instability. As the advocates of vehicle-to-grid (V2G) technology point out, electric vehicles could provide the key to making wind and solar power practical on a large scale.

But while an entirely-electric vehicle with a truly high-performance battery would have clear engineering advantages over cars with internal combustion engines or fuel cells, we can't ignore the influence of infrastructure and consumer habits in determining the rate at which such a substitution might take place. Even if the US electrical grid has enough idle overnight capacity to recharge a couple of hundred million vehicles, as a 2006 study indicated, it's not clear that it has the fuel supply to spin all those gas and steam turbines (see yesterday's posting on natural gas.), unless we convert our oil refineries to make a lot more kerosene and a lot less gasoline. And while Mr. Agassi's Project Better Place might have an ideal solution for drivers who need to recharge in a few minutes, rather than overnight, his concept must still be proven, and I would love to see how his business model manages the large battery inventory it seems to require.

A few months ago I had the opportunity to drive one of GM's new limited-production fuel cell SUVs, which recently got a boost from Richard Branson's Virgin Group. I was impressed that they had managed to make a fuel cell vehicle seem so normal. But while conventional cars and hybrids have the inertia of infrastructure and consumer expectations behind them, the same can't be said for automotive fuel cells, which because of their cost, complexity and supply-chain hurdles might simply be shoved aside by greatly-improved batteries. Developments in the next year or two could determine the outcome of a very long competition.

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