While roaming around the Siemens site, this article I thought was very enlightening. I especially loved the photo of the first trolleybus! However this quote disturbed me:

"That's because power plants in the global electricity mix emit some 600 g of CO₂ per kilowatt-hour, which corresponds to 90 g for every kilometer driven by an electric car. That's a lot less than the 120 to 160 g of CO₂ emitted per kilometer by a typical mid-range automobile with a combustion engine"

This actually sucks. 90g is what the Polo Bluetec will emit. So why would anyone go electric at all? Well, hopefully the grid will get greener. Also, the displacement of emissions to outside the city is generally healthier.

A tiny bit more research got this analysis from Paul Chefurka showing similar numbers (135-200g/km) in the US, but only 45-70g/km in Ontario Canada. This shows that greener grids are better investments for electric cars.

But unlike the mechanical systems of the past, the drive systems of the future will have brains. Intelligent electronic systems will manage components, charging and discharging procedures, as well as the brake energy recovery processes. And all of this will be designed to ensure that the energy efficiency, and thus the environmental soundness, of electric cars is much higher than the values achievable by combustion engines. The well-to-wheel efficiency (from energy source to operation) of a good electric vehicle today is over 70 % – based on renewable energy sources –, whereas the efficiency rating of most combustion engines is only around 20 %.

Even if the power for electric cars isn't generated from renewable sources such as wind and sun, the level of CO₂ emissions from such vehicles is still much lower than that of any combustion engine. That's because power plants in the global electricity mix emit some 600 g of CO₂ per kilowatt-hour, which corresponds to 90 g for every kilometer driven by an electric car. That's a lot less than the 120 to 160 g of CO₂ emitted per kilometer by a typical mid-range automobile with a combustion engine.