| Answer | Crossword Clue |
|---|---|
| FUEL | Energy source for engines |
| STEAM | Energy source in old engines |
| STEAM | Power source for early engines |
| SUN | Energy source for plants |
| CARB | Energy source, for short |
| ATP | Biochemical energy source, for short |
| GLUCOSE | Important energy source for the brain |
| COALBIN | Place for a potential energy source |
