We use energy for many aspects of our daily lives.
Energy powers our schools, our homes, our cars.
We use energy for heating and cooling, for cooking and refrigeration, for washing and drying our clothes. The problem is that as the world s population increases, the demand for energy also increases. Most power plants currently use nonrenewable energy sources , such as coal, fuel, and natural gas, to meet their energy demands. Renewable energy sources , such as solar energy, wind power, and hydroelectricity, offer a cleaner, more environmentally friendly source of energy. Yet, these sources are currently very expensive or limited to certain geographical regions.