Across
- 2. working or produced by machines or machinery
- 6. liquid derived from petroleum, used for fuel
- 7. electricity from the flow of water
- 10. a natural fuel formed from the remains of past organisms
- 12. relating to the internal heat of the Earth
- 14. having to do with the Sun
Down
- 1. not depleted when used
- 3. depleted when used
- 4. cutting of trees
- 5. movement of air
- 8. a supply or stock
- 9. operating by electricity
- 11. rock made from carbonized plant matter, used for fuel
- 13. drilling into the Earth