Will Electric Cars Lower Nitrous Oxide Emissions?

This post, part of a series we're running all about electric cars, was written by William R. Harris from HowStuffWorks.com.

When it comes to global warming, carbon dioxide ranks as the No. 1 offender. Why? Because it's the most common gas responsible for the greenhouse effect -- the process by which the atmosphere traps heat and warms the planet. But did you know there's another more potent greenhouse gas? Nitrous oxide, the same stuff we call laughing gas, is 300 times more efficient than carbon dioxide when it comes to holding in solar energy like a blanket. And since the 1970s, when most internal-combustion cars and trucks came equipped with catalytic converters, nitrous oxide has played an increasingly significant role in nudging the mercury higher.

Electric vehicles, or EVs, seem like an ideal solution to the nitrous oxide problem. They don't burn gasoline, don't produce any nasty tailpipe emissions and, as a result, don't require catalytic converters. No catalytic converters, no laughing gas. No laughing gas, no greenhouse effect, or at least no effect we can attribute to nitrous oxide. Except, of course, it's not that simple: The network of coal-burning power plants used to generate electricity looms as another big source of nitrous oxide emissions. In 2008, those power plants produced 9.7 MMTCO₂e of nitrous oxide, which stands for "million metric tons carbon dioxide equivalent," the standard unit of measurement.

Because EVs need electricity to go from point A to point B, and much of the country's electricity comes from coal-fired power plants, it's fair to question whether driving battery-powered cars can actually penetrate the nitrous oxide problem. Several studies have tried to answer this question, predicting that EVs will reduce the production of several major urban pollutants. One study described in a 1990 issue of Scientific American estimated that the United States could cut nitrous oxide emissions by 67 percent by pumping electricity into cars instead of gasoline. The reduction of other pollutants, such as hydrocarbons and carbon monoxide, would be even more profound.

Current data seems to support these predictions. Since 2003, nitrous oxide emissions related to driving have decreased each year. Between 2007 and 2008 alone, the emissions dropped by almost 5 percent. Higher gasoline prices and economic uncertainty definitely played a role in this trend, but so has the adoption of fuel-efficient vehicles. According to the Electric Drive Transportation Association's Electric Drive Fact Sheet, nearly 1.5 million hybrid vehicles have been sold in the U.S. since 1999. Chrysler's Global Electric Motorcars has sold more than 40,000 neighborhood electric vehicles -- battery-powered, zero-emission vehicles used in cities, college campuses, military posts and other settings where short-range driving is the norm.

As EVs gain wider acceptance (President Obama wants to see 1 million plug-in EVs on the roads by 2015), nitrous oxide emissions should continue their downward trend. Who ever thought that having less laughing gas could actually make us smile?