Across
- 2. fuels - energy that is created by remains of animals.
- 4. - it's another way of saying this energy will run out one day.
- 7. - Original.
- 8. dioxide - the gas that we breathe out.
Down
- 1. - wood, garbage, crops, alcoholic fuels and landfill gas are all types of ...
- 3. to produce.
- 5. - this energy will run out one day.
- 6. - a way to measure hot and cold.