Across
- 3. standards on which a decision may be based
- 5. any harmful substance that affects Earth's land, air or water
- 6. process, series of steps that engineers follow to come up with a solution for a problem
- 8. power, power obtained from solar energy
- 9. energy, energy obtained from Earth's interior
- 10. fuel, a source of energy made from remains of ancient, once living things
- 11. energy source, a source of energy other than burning a fossil fuel
- 12. an original or first model of something from which other forms are copied or developed
- 13. resource, something that is found in nature and is valuable to humans
Down
- 1. resource, a material that is replaced quickly in nature
- 2. electricity produced by waterpwower
- 3. the act of saving, protecting, or using resources wisely
- 4. resource, natural materials or sources of energy that are useful to people and can not be replaced easily
- 7. things that may limit a solution to a problem