Friday, September 05, 2008

Are Electric Cars More Harmful to the Environment than Gasoline-Powered Cars?

Because we’re likely to see a massive shift to personal electric transportation in the next few years, this is an important question. Ideally we should reduce our carbon footprint in the transition, not increase it, but here are the facts:

• Burning a gallon of gasoline releases 19.6 pounds of CO2 into the atmosphere.

• A gallon of gasoline has as much energy as 33kwh of electricity.

• For every kwh of electricity that a coal-fired power plant produces, 2.2 pounds of CO2 is released into the atmosphere.

These statistics seem to indicate that it is better to burn a gallon of gasoline and release 19.6 pounds of CO2 than to use an equivalent amount of electricity and release 72.6 pounds (33kwh X 2.2 pounds), into the atmosphere. It seems that driving an electric car will be much more harmful to the environment than driving a gasoline-powered car. Could this be true?

These statistics suggest that an electric car, starting with a fully charged 33kwh battery pack, would travel as far as a similarly-sized gasoline powered car could go on a single gallon of gasoline. However, the Chevy Volt is expected to be able to travel 40 miles on a fully-charged 16kwh battery pack. What gives? The discrepancy is due primarily to the fact that electric motors are 90 to 95% efficient, while gasoline engines are only 20 to 30% efficient. In reality, driving an electric car will produce about the same amount of pollution as driving a gasoline-powered car, it just moves the source of the pollution from the tailpipe to the power plant.

The net result, it seems, is that we accomplish nothing by switching to electric cars, but that’s not entirely true either. It’s easier to stop pollution at a few power plants, than it is to stop it at the tailpipes of millions of cars. Electric cars also give us the opportunity to use electricity from clean sources, such as solar PV panels or hydro-electric plants. So instead of releasing millions of tons of pollution each year, we’ll soon have an opportunity to drive our personal automobiles without releasing any CO2 into the atmosphere. That’s something we’ll never be able to do with gasoline-powered cars.

The millions of electric cars we’ll see on the road within a few years will all need to be recharged each night. It’s clear that our priority as a nation should be to clean-up or eliminate coal-fired power plants. Expensive schemes, such as carbon sequestration, are not the best use of federal funds. Promoting solar-, wind-, and hydro-power would be better. Energy from a modestly-sized solar-electric (PV) array on a single residential rooftop can offset 2000 pounds of CO2 each day, so just imagine how beneficial a million solar roofs would be. That’s 2 billion pounds of CO2 each day!

Concerned about electric car performance? Don’t be. Electric cars can be built to be both highly efficient and very quick. Tesla Motors has already proven that. Increasing the size of an electric motor improves both horsepower and efficiency. On the other hand, a big motor is needed to make a gasoline-powered car quick, but gas mileage suffers as a result.

Driving a personal automobile doesn’t have to be an environmental disaster. The switch to electric transportation can have a positive effect on the environment. All that we need now is intelligent leadership and an aggressive plan. Maybe if we can get our politicians to stop taking money from coal and oil interests, we might just get legislation that is good for the environment for a change.



Carbon Dioxide Information Analysis Center:

Chevy Volt Site:

Tesla Paper:


Damon said...

Hi SJ,

A related question:

Environmental Cost of Hybrids' Battery Recycling?



Sal Costello said...

Great site John! Thanks!

Anonymous said...

Took me time to read the whole article, the article is great but the comments bring more brainstorm ideas, thanks.

- Johnson