Do electric cars really help the environment?

President Obama thinks so, so does Leonardo DiCaprio and many others.

The argument goes like this.

Regular cars run on gasoline, a fossil fuel that pumps CO2 straight out of the tailpipe and into the atmosphere.

Electric cars run on electricity. They don't burn any gasoline at all.

No gas? No CO2.

In fact, electric cars often advertise this creating zero emissions.

But do they really? Let's take a closer look.

First, there's the energy needed to produce the car.

More than a third of the lifetime carbon dioxide emissions from an electric car

comes from the energy used to make the car itself, especially the battery.

The mining of lithium, for instance, is not a green activity.

When an electric car rolls off the production line,

it's already been responsible for more than 25,000 pounds of carbon dioxide emissions.

The amount for making a conventional car, just 16,000 pounds.

But that's not the end of the CO2 emissions.

Because while it's true that electric cars don't run on gasoline,

they do run on electricity, which in the US is often produced by another fossil fuel.

Cold.

As green venture capitalist Vinod Kostler likes to point out,

electric cars are coal-powered cars.

The most popular electric car, the Nissan Leaf,

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