So where's the power going to come from?

There are basically four ways to power an automobile:

Gasoline/Petrol
The standard fuel for passsenger cars worldwide, and particularly in the USA. It has a high energy cost in refining. Its major disadvantage from the CO2 point of view is that it's at its worst (least efficient and most polluting) when the car is idling or operating on half-throttle, which is what happens on a typical commuter drive.

Diesel
Unfashionable for many years, and generally regarded as only suitable for tractors and buses, diesel is making a comeback - particularly in Europe. It's much more economical for city driving and has a lower energy cost in refining. There are some concerns about the particulate emissions. However, the main advantage of diesel power is that the vehicle can run on biofuels, and particularly on recycled oils, with very little conversion.

Hydrogen
As far as I can tell, hydrogen cars are mostly there to provide the appearance of environmental-friendliness for the energy companies. Hydrogen is used in fuel cells to generate electricity with no detrimental emissions. However, the practicalities of hydrogen use suggest to me that it will be decades before we drive hydrogen-powered cars.

Electricity
Electric cars have been around for more than a century. The technology is reasonably stable and well understood. The main drawback is the storage problem (batteries - heavy and with limited lifetimes) - but this problem is being reduced at a rapid rate, using new technologies such as lithium-ion nanostructured cells.

I have a personal fondness for electric cars. They're clean, quiet, reliable, and amazingly simple. Here's a photo of a small electric car built by my students at the University of Cape Town. The students are Jaston Sikaundi and Mark Britten, who worked on the electrical design - Craig Peters designed and built the chassis.

So, I'm biased towards electric cars. However, there's a big ideological hump to get over here. Most of the electricity in the world is generated by burning fossil fuels. If you dump the SUV and then use an electric car charged from a fossil-fuel power station, you've improved the efficiency of the process - more real energy for your money, so to speak - but it's not really anything to crow about.

My approach is to assume that by the time we get large-scale adoption of electric cars, we'll have siginficantly changed our power generation strategy. Unfortunately, there's only one way to do this in the time available, and that's widespread construction of nuclear power stations (renewables, such as wind, solar and wave energy, just don't generate enough electricity consistently to replace coal-fired stations).

So, to sum up: the car's going to be (at least partly) electric-powered and the electricity's going to come from a nuclear power station. Global warming - almost nil. Difficult compromises regarding nuclear waste and proliferation - oh yeah.