Three Mile Island is a focal point of great concern. An accident at the nuclear power plant in 1979 brought nuclear energy and its potential effects on the environment and to people's health to the public's attention. Balancing our desire for energy with our need for a healthy environment and for our own health often comes with risks. But there are also risks associated with not using nuclear energy. Coal-fired power plants may be relatively safer but pollute much more and contribute to global warming.