Across
- 2. considered "clean" but releases toxic chemicals
- 4. clean renewable energy source
- 5. solar panels
- 6. most abundant in coal
- 8. uses machinery to produce energy
- 10. can be replenished within our lifetime
- 12. energy from heat from magma in earth
- 13. does not use machinery to produce energy
- 14. element to reduce to half its initial value
Down
- 1. recovering gas and oil from rock shale
- 3. densest for of coal
- 7. using steam left over to produce heat.
- 9. store excess energy for later use
- 11. used in less developed countries for energy