| A | B |
|---|
| Wind | The result of uneven heating of Earth's atmosphere by the sun. |
| Steam and heat | Geothermal energy produces this on the surface of the Earth. |
| Ecosystem | Dams built for hydroelectric plants can upset this and the region around it. |
| Biomass | Trees, grain, and manure are examples of this. |
| Electricity | The heat from the sun can be used for cooling as well as heating by using solar energy to generate this. |
| Water | Hydroelectric power could be generated by using this. |
| Sun | The primary source of renewable energy is this. |
| The Earth | This is a direct source of geothermal energy. |
| Southern | What states use solar energy the most? |
| Pollution | Energy created by the sun or wind adds little of this kind of problem. |
| Electricity | Ocean tides can be used to generate this. |
| Windmill and water wheels | These are devices that use renewable energy sources. |
