Last week The Economist ran an online debate considering the motion "Biofuels, not electricity, will power the car of the future". I was privileged to be invited as a guest contributor along with Tim Searchinger of Princeton University. The two primary "speakers" were Alan Shaw of Codexis and Sidney Goodman of Automotive Alliances. Here is my contribution to the debate, in which I basically rejected the false dichotomy of the motion (the first two 'graphs follow):
The future of transportation power sources will not be restricted to "either/or". Rather, over the coming decades, the nature of transportation fuel will be characterised by a growing diversity. The power sources for the cars of the future will be determined by the needs those cars address.
Those needs will be set for the market by a wide range of factors. Political and economic pressures are likely to require reducing greenhouse gas emissions and overall energy use per trip. Individuals behind the wheel will seek to minimise costs. But there is no single fuel that simultaneously satisfies the requirements of carbon neutrality, rapid refuelling, high-energy density for medium- to long-range driving and low cost.
I find it interesting that the voting came down so heavily in favor of electricity as the "fuel" of the future. I suppose the feasibility of widespread electric cars depends on what you mean by "future". Two substantial technology shifts will have to occur before electric cars displace those running on liquid fuels, both of which will require decades and trillions.
First, for the next several decades, no country, including the US, is likely to have sufficient electricity generating resources and power distribution infrustructure to convert large numbers of automobiles to electric power. We need to install all kinds of new transmission lines around the country to pull this off. And if we want the electricity to be carbon neutral, we need to install vast amounts of wind and solar generating capacity. I know Stewart Brand is now arguing for nuclear power as "clean energy", but that still doesn't make sense to me for basic economic reasons. (Aside: at a party a few months ago, I got Lowell Wood to admit that nuclear power can't be economically viable unless the original funders go bankrupt and you can buy the physical plant on the cheap after all the initial investment has been wiped out. Sweet business model.)
Second, the energy density of batteries is far below that of liquid hydrocarbons. (See the Ragone chart included in my contribution to The Economist debate.) Batteries are likely to close the gap over the coming years, but long distance driving will be the domain of liquid fuels for many years to come. Yes, battery changing stations are an interesting option (as demonstrated by Better Place), but it will take vast investment to build a network of such stations sufficient to replace (or even compete with) liquid fuels. Plugging in to the existing grid will require many hours to charge the batteries, if only because running sufficient current through most existing wires (and the cars themselves) to recharge car batteries rapidly would melt those wires. Yes, yes -- nanothis and nanothat promise to enable rapid recharging of batteries. Someday. 'Til then, don't bother me with science fiction. And even if those batteries do show up in the proverbial "3 to 5 year" time frame, charging them rapidly would still melt most household power systems.
In the long run, I expect that electric cars will eventually replace those powered by liquid fuels. But in the mean time, liquid fuels will continue to dominate our economy.