Model answer:

The diagram shows a process for producing electricity for (1)_________. The equipment consists of a large tank, boxes and pipes that would be able to fit into a garage-sized room.

Electricity is produced using methane gas, generated from a mix of compost and water in a large steel tank. The tank is about the same height as a person and about twice (2)_________. Methane rises to the top of the tank and is collected and stored in a gas storage system. The (3)_________ gas is the fuel source used in the energy conversions that happen next.

Once compressed in a gas compressor, the methane (4)_________ a combustion engine, which in turn produces mechanical energy. Having been (5)_________ to a generator, the mechanical energy is then transformed into electrical energy, which is then stored in a battery. (6)_________ the electricity is ready for home use.

ANSWER KEY

1. home use

2. as wide

3. stored

4. fuels

5. transferred

6. at this stage