Renewable energy has been used for thousands of years. From the heat of the sun to dry clothes, fruit and vegetables, to wind energy to grind corn or to power sail boats, renewable energy sources can be harnessed to do work.

Homes have been built to use the sun's rays to warm them in the winter. People and companies have used solar water-heating systems. Others have installed photovoltaic panels to make electricity. Still others have tapped the heat below ground in geothermal electricity systems, direct-use geothermal, or ground-source heat pumps.

Renewable Energy Basics