There are several designs for biogas generators, but they all need..

• A way of putting the waste material in
• A way of removing the digested waste material (this can be used as a fertiliser)  
• A way of removing the biogas and transporting it to were it is needed

In GCSE Biology, waste material is put into the tank with the bacteria in anaerobic conditions. It is left to ferment until all of the gas has been produced.

• The gas is collected
• The tank is then cleaned and refilled.
• The digested material can be collected as used as fertiliser.

There are two advantages of batch biogas production in GCSE Biology curriculum:

1. Useful for small scale production
2. Can be cleaned easily if contaminated

1. Takes time and energy to set up
2. Can take up to four weeks before the methane is produce (before all of the oxygen in the tank has been used up for aerobic respiration)
3. Only small batches of biogas produced

In GCSE Biology, this production means waste material is continuously added to the tank to 'top up' gas production

• The gas is collected
• This continues for long periods of time without a break in production
• The digested waste material is collected as used for fertiliser

1. Efficient - don't have to close down the fermenter
2. Methane is produced all of the time
3. Continuous use of waste materials

Usually in GCSE Biology, there are four disadvantages regarding this biogas production

1. More expensive to set up as it is more complex
2. Needs a continuous feed of waste
3. Large amounts of gas need storing
4. Can't control the temperature, so it is slow in winter.

End of the topic!

CLICK HERE TO LEARN MORE ABOUT OUR GCSE BIOLOGY COURSES

Drafted by Gina (biology)