Ask Dr. Bill

Your global warming questions answered

Posted: 11-May-2006; Updated: 09-Jan-2007

I have seen lots of car ads promoting 'E85' fuel. What is E85 and is it a real alternative to gasoline?

E85 is an ethanol-gasoline blend that is 85% ethanol and 15% gasoline. There are many potential benefits to ethanol, which is currently made mostly from corn. For one, they can reduce dependence on foreign oil. And it is a growing source of energy -- the Agricultural Working Group has called on farmers to meet 25% of America's energy needs by 2025.

But the environmental benefits of biofuels are not universal. For example, global warming pollution savings from biofuels can vary substantially depending on how crops are grown and how the fuel is made. Environmental Defense is working with farmers and commodities groups to develop a low-carbon certification program for biofuels. This program would work just like the way we certify organic foods. A certified low-carbon biofuel would be one that was produced using practices that minimized the emissions of global warming pollutants. Ultimately, when national global warming caps are in place, certified ethanol could be an important fuel alternative to help cut America's global warming pollution.

How do I find out if I can use E85 in my car?

Today, while nearly every car can run on E10 (gasoline blended with 10% ethanol), only about one in forty cars can run on E85. Find out if your car can run on ethanol, then use the alternative fuel station locator to find out where to fill up.

What's the bottom line? Should my next car be one that runs on E85 or should I look for other fuel efficient models like hybrids?

Until we get a national low-carbon certification program in place for ethanol and other biofuels, the best option is to buy a car that gets high gas mileage. Many hybrids, but not all, are among the best fuel-efficient alternatives on the market. The key metric for cutting global warming pollution from automobiles and also saving money at the gas pump is fuel efficiency, or miles-per-gallon.