Select your localized edition:

Close ×

More Ways to Connect

Discover one of our 28 local entrepreneurial communities »

Be the first to know as we launch in new countries and markets around the globe.

Interested in bringing MIT Technology Review to your local market?

MIT Technology ReviewMIT Technology Review - logo

 

Unsupported browser: Your browser does not meet modern web standards. See how it scores »

{ action.text }

Romm reminds us of the growing scientific consensus: we must quickly reduce greenhouse-gas emissions to avoid the worst effects of global warming. Therefore, Romm argues, the job of political leaders is clear. Among other things, they must rapidly adopt tighter efficiency standards for homes, offices, and industry; mandate strict increases in automobile fuel economy, which means widespread adoption of ultra-efficient cars, including hybrids; and build as many wind and solar plants as possible, while cautiously expanding nuclear power. Romm even argues that we could cut nationwide carbon dioxide emissions by two-thirds without increasing anyone’s annual electric bill. He cites California’s three-decade record of aggressive investment in cleaner energy technologies and energy-efficiency programs. When these investments are amortized, costs stay flat while power consumption and carbon dioxide emissions plunge. Today, Romm writes, a Californian has an electric bill no larger than the average American’s but generates just one-third the carbon dioxide.

The reason hydrogen-powered cars would produce more carbon dioxide emissions than regular cars starts with the fact that it takes energy to create hydrogen. One way to produce hydrogen is to extract it directly from fossil fuels; indeed, a 2004 National Academy of Sciences study predicted that fossil fuels would be the main source of hydrogen for “several decades.” The other way is to split water molecules using electricity. Naturally, BMW talks up this approach, envisioning electricity that would ultimately be supplied by renewable sources. BMW brochures feature the Hydrogen 7 parked in front of wind turbines and shiny photovoltaic arrays. But renewable sources furnish only 2 percent of the world’s electricity (not counting hydropower’s 16 percent). Coal, by contrast, supplies 39 percent–and is the worst emitter of carbon dioxide, watt for watt. Clearly, a great use for renewable power is to replace coal power. But is it worthwhile to divert even a small part of it to the task of manufacturing hydrogen?

According to Romm’s analysis, the math for hydrogen cars simply doesn’t work out. Burning coal to generate one megawatt-hour of electricity produces about 2,100 pounds of carbon dioxide. It follows that one megawatt-hour of renewable power can avert those emissions. Using that electricity to make hydrogen would yield enough fuel for a fuel-cell car to travel about 1,000 miles, Romm says. But driving those 1,000 miles in a gasoline-­powered car that gets 40 miles per gallon would produce just 485 pounds of carbon dioxide. In this sense, Romm says, a vehicle powered by hydrogen fuel cells would indirectly create four times the carbon dioxide emissions of today’s most efficient gasoline cars.

And the numbers for the Hydrogen 7 are worse, because it burns hydrogen. Combustion produces thrilling torque, but it’s far less efficient than fuel-cell technology. Also counting against the Hydrogen 7 is the fact that it stores hydrogen as a liquid; chilling hydrogen and compressing it into liquid form consumes more energy than storing it as a compressed gas. “It’s safe to say this is a pointless activity,” Romm says. “BMW has managed to develop the least efficient conceivable vehicle that you could invent.”

BMW’s new car is a marvelous piece of engineering. But it is also a distraction from the real issues: we must burn less fossil fuel and reduce our greenhouse-gas emissions today. Innovative automakers like BMW should turn their remarkable skills to making cars that are more efficient–such as BMW’s new 118d economy hatchback, which on average gets 50 miles to the gallon. But the Hydrogen 7 is hardly the “new standard of sustainable pollutant-free mobility” that BMW proclaims. Draeger’s offer is one we would be wise to refuse.

Hell and High Water: Global Warming–the Solution and the Politics–and What We Should Do
By Joseph J. Romm William Morrow, 2007, $24.95

64 comments. Share your thoughts »

Credit: BMW

Tagged: Energy, efficiency, global warming, emissions, DOE

Reprints and Permissions | Send feedback to the editor

From the Archives

Close

Introducing MIT Technology Review Insider.

Already a Magazine subscriber?

You're automatically an Insider. It's easy to activate or upgrade your account.

Activate Your Account

Become an Insider

It's the new way to subscribe. Get even more of the tech news, research, and discoveries you crave.

Sign Up

Learn More

Find out why MIT Technology Review Insider is for you and explore your options.

Show Me