Renewable

5. Means saving energy
8. A loop of piping that circulates a liquid underground.
9. The percentage of energy put into a system that does useful work.
11. electricity produced in a small stream without having to build a big dam
12. All sources of energy, including renewable sources, affect the _________.
14. The production of two useful forms of energy from the same fuel source
15. The most abundant element in the universe.
16. Energy from sources that are constantly being formed.

1. Large arrays of wind turbines are called ___________
2. May be the future of engines
3. Convert the sun’s energy to electricity
4. A major source of ethanol in the U.S
6. Use a small, efficient gasoline engine most of the time, but also use an electric motor when extra power is needed
7. Product of bacteria decomposing organic wastes
10. deposits of water in the Earth’s crust that are heated by energy within the Earth
13. The movement in the oceans and seas caused by gravitational attraction between the sun, earth, and moon.