Uncertainty about the future of fusion research has increased the importance of "renewable" energy sources. Among the most important of these sources are hydroelectric, solar, and wind. As you will see, renewable energy sources' main assets are their environmental cleanliness and their virtual inexhaustability. Major drawbacks, however, are limited energy production (in most cases not suitable for large-scale power generation) as well as relative costliness to build and maintain. In light of diminishing fossil fuels, however, renewable energy may end up as the energy of choice for the 21st century.

Hydroelectric

Solar

Biomass

Wind

Geothermal