Energy

3. a natural substrate for the production of ethanol as fuel
4. large pits lined with clay where rubbish is deposited.
7. Starchy crops may have to be pretreated with these before fermentation can proceed
10. Zymomonas mobilis can tolerate high levels of ethanol and is this type of micro-organism
12. type of processing where raw materials are constantly added and product constantly being removed
13. substrate for production of biogas in sewage works
14. animal waste produced from intensive farming techniques
15. a by product of fermentation

1. organic material produced by green plants that can be used as an energy source
2. process by which sugar is converted to alcohol
5. container dug into the ground to collect animal and domestic waste and produce biogas
6. type of processing with all raw materials needed inside an enclosed container at start
8. ethanol and petrol mixture
9. conditions required for production of biogas
11. a gas produced from the decay of remains of animals and plants