Across
- 1. : Largest exporter of petroleum
- 4. : Solar heating that does not use mechanical equipment
- 6. : Solar panels that convert sunlight directly into electricity
- 9. : Energy source that uses uranium-235
- 10. : Device spun by steam, wind, or water to generate electricity
- 13. : Renewable energy source that uses dams
- 14. : Energy from moving air
- 16. : Period when electricity demand is highest
- 18. : Fossil fuel formed from marine organisms over millions of years
- 19. : Type of nuclear reaction used in power plants
- 20. : Energy source formed from compressed peat over millions of years
Down
- 2. : Highest quality and most energy-dense type of coal
- 3. : Time required for 50 percent of a radioactive substance to decay
- 5. : Greenhouse gas released during natural gas extraction
- 7. : Solar heating that uses pumps or mechanical systems
- 8. : High-pressure shale cracking process used to extract natural gas
- 11. : The cleanest fossil fuel mostly composed of methane
- 12. : Using waste heat from electricity generation to heat buildings
- 15. : Fuel commonly used in developing countries for cooking and heating
- 17. : Biofuel made from fermented corn or sugarcane