When I first enrolled in this class, I was under the spell of hydrogen fuel-cell powered cars. I've had a change of heart since, and now I'm more into plug-in hybrids. One problem with plug-ins I hadn't really thought about was the air conditioning that I have been taking throughout all my childhood summers here in Texas.
Conventional cars use the built-in inefficiencies of the internal combustion engines to heat the passenger compartment and a gasoline powered compressors to cool the passenger compartment. Purely electrically driven vehicles won't be able to use either of these means of energy for climate control. This is a huge issue because we Americans have become so reliant on air conditioning even though it's not a necessity.
Thermoelectrics use the electrical current supplied by the hybrids batteries to generate heat and to cool air. Simple capacitors can be used to generate heat when a current is applied, but cooling air is a little harder. Cooling devices would work when current is run through a similar heating device in the opposite direction, but these devices depend on nanomaterials that are still under development.
What is really cool about using thermoelectrics to control the car's climate is that they can be installed in very specific areas. That means each passenger can control their own climate, and the devices can be turned off when there's no one in that seat leading to huge energy savings.
The biggest problem with plug-ins from the manufacturers' point of view is perception: they want drivers to step into a plug-in without noticing any differences. Only when drivers are that comfortable with the technology do manufacturers believe they can sell the cars. Thermoelectrics will go a long way towards providing the comfortable climate drivers are used to, and in doing so, will bring plug-in hybrids down from the drawing boards and closer to garages around the world.