Many people hope that hydrogen, generated cleanly by harnessing the power of the sun and wind, may someday displace gasoline as the main automotive fuel.

But a new study from the Seattle-based Institute for Lifecycle Environmental Assessment argues that if the goal is to reduce greenhouse gas emissions, then generating hydrogen for fuel-cell powered cars isn’t a particularly smart investment, at least not in the near-term.

Yes, burning gasoline is responsible for a lot of climate-warming emissions. But coal, the main source of electricity in the United States, is far worse. On net, using solar and wind power to offset generation from coal-fired power plants would be two and a half times as effective in reducing climate-warming emissions as using clean energy to generate hydrogen for fuel cell cars.

  • Using hydrogen as a vehicle fuel carries some inefficiencies—you have to convert electricity into hydrogen, and then convert the hydrogen back into electricity. Energy is lost at each step. In fact, the authors conclude that battery-powered cars would be twice as efficient at reducing greenhouse gas emissions than would fuel cell vehicles, largely because storing energy in a battery is more efficient than storing it as hydrogen.

    As always, the usual disclaimers apply. Yes, replacing gasoline powered cars with fuel cell vehicles has some obvious advantages, both for greenhouse gases and for urban air quality. And yes, there’s no reason we have to choose one or the other—renewable energy does have enough potential that, in theory at least, it could replace all our existing electricity and our gasoline consumption.

    But if the point is to get from where we are now to where we could be, we have to make the smartest buys first. That will buy us both the money and the time to make the tougher investments later. By that criterion, we should spend less of our energy (so to speak) on creating a vehicle fleet that runs on hydrogen, and more on getting rid of coal-fired power plants.