Across
- 6. Can be replaced
- 7. Energy dense
- 9. Natural gas extraction
- 11. Mother nature's gift to energy
- 12. End goal
Down
- 1. Can be used up
- 2. Best FF for environment
- 3. Radioactive
- 4. Completely replaced
- 5. Fractional distillation
- 8. "Liquid Gold"
- 10. Worst fuel for environment