You may probably have this experience when you were small: whenever your dad drove a pretty beat-up car along a steep slope, he would say, "I have to turn off the air-conditioner. Or the car will break down."
During that time, you might not realize that the air-conditioner indeed sucks up lots of energy from the engine. Of course, modern cars do much better than that nowadays, but still, wouldn't it be great if your air-conditioner takes power from somewhere else so that your car uses less fuel? How about getting it from the sun?
Not sure if Professor Eric Cheng from Department of Electrical Engineering had similar experience when he was young, but he invented a solar-powered air-conditioning system for vehicles that is independent of the engine. Photovoltaic panel on the car collects solar energy and stores it in a battery which will be the sole energy source to run the air-conditioner during idling, night time or rainy days. With the additional energy source for the air-conditioner, the system also reduces the demand on fossil fuel when the vehicle is in motion. So, that's less harmful emission. Thank God.
