The low down on plug-ins

I've read detailed and well-researched reports that say that plug-in hybrids will decrease pollution and carbon emissions.

The problem is, I've also read detailed and well-researched reports that say the exact opposite. What is going on here? How could such obviously contradictory reports both be true?

Well, to work out some of the kinks concerning how plug-in hybrids work, I thought I'd make a list of environmental pros and cons:

Pros:

• PHEVs use less gasoline. Gasoline makes the world suck more.
• PHEVs get greener as the grid gets greener.
• Power plants (which charge PHEVs) are more efficient than car engines, creating more energy per unit of carbon.
• 500 power plants are easier to regulate than 100 million cars.
• Power plants emit less NOx, hydrocarbons, and other smog-causing pollutants.
• PHEV technology could allow for an intelligent grid that would allow cars to sell their energy back to the grid during peak demand, decreasing the need for more power plants.
• PHEV batteries have less environmental impact than current nickel batteries.

Cons:

• Power plants produce far more SO₂ than cars (especially old coal plants).
• In areas where coal generates most of the power, PHEVs can produce more carbon than similar sized cars.
• PHEVs increase electricity demands, which increases coal mining, which is bad news.
• PHEV batteries are expensive and need a lot of resources to create and recycle.

As you can see, it isn't clear-cut here. In fact, I'm fairly certain that this isn't even a complete list.

I'm most influenced by the fact that gasoline hybrids will always remain as dirty as they are today, while plug-ins will continue to get greener as the renewable energy economy matures.

Of course, this assumes that the renewable energy economy will mature. But with 42 gigawatts of renewables planned for the U.S. already, I think that's a fairly safe bet.

Still, I think this is an open debate, which is why I'm unleashing the beta of the EcoGeek forums to discuss this issue. If you've got anything to add, or want to read a bit more about the controversy, check out the forum topic I just created about it. Hopefully we can all inform each other. No registration required!

Sources: USA Today and WBCSD