Energy

2. introduction of harmful materials into the environment
3. removal of trees for lumber, crops, extraction, or development
4. organic matter used as a fuel for generation of electricity
5. the chemical element of atomic number 92, a dense gray radioactive metal used as a fuel in nuclear reactors.
7. resources that can replenish themselves over a period of time even as they are used.
8. the ability to be maintained at a certain rate or level
9. relating to or determined by the sun
12. unable to be used up
16. the natural movement of air
18. the generation of electricity using flowing water
19. a natural fuel such as coal or gas, formed in the geological past from the remains of living organisms.
20. relating to or produced by the internal heat of the Earth

1. energy generated by ways that don’t deplete natural resources or harm the environment
6. materials or substances such as minerals, forests, water, and fertile land that occur in nature
7. to fill or build up the supply again
10. a natural substance that is not replenished with the speed at which it is consumed.
11. preventing the wasteful use of a resource
13. energy stored inside of an atom
14. collecting and processing of materials that would be thrown away and turning them into new products
15. fossil fuel formed by the remains of ancient organisms
17. process of materials worn away and transported by natural forces