Conservation of Natural resources

4. Able to be maintained at a certain rate or level.
6. The energy received by Earth from the sun in the form of radiation.
9. Harmful substances in the air, water, or soil.
12. . The process of recovering valuable or useful materials from waste or scrap
14. The gas formed when carbon is burned, or when people or animals breathe out.
15. Resources that are constantly being supplied.
16. Resources that are being used up faster than they are made.
20. A gas that contributes to the greenhouse effect by absorbing infrared radiation, e.g., carbon dioxide and chlorofluorocarbons.

1. Electricity produced by the kinetic energy of water moving over a waterfall or dam.
2. A renewable resource that comes from the heat from inside the Earth.
3. A gradual increase in the temperature of Earth’s atmosphere.
5. A change in global or regional climate patterns.
7. Energy-rich substances formed from the remains of once living organisms
8. The energy released by a fission or fusion reaction; the binding energy of the atomic nucleus.
10. The chemical element of atomic number 92, a gray, dense radioactive metal used as a fuel in nuclear reactors.
11. A form of hydropower that converts the energy obtained from tides into useful forms of power
13. The use of air flow through wind turbines to mechanically power generators.
17. Any natural material that is used by humans, such as water, petroleum, minerals, forests, and animals.
18. To save or reduce the use of something.
19. A renewable resource made from things that were once alive.