Using Biogas Generators

Question 1

What is a batch generator?

Answer 1

A batch generator makes biogas in small batches. They are manually loaded up with waste, which is left to digest, and the by-products are cleared away after each session.

Question 2

What is a continuous generator?

Answer 2

A continuous generator makes biogas all the time. Waste is continually fed in, and biogas is produced at a steady rate. They are more suited to large-scale biogas projects.

Question 3

What three things must a biogas generator have?

Answer 3

1) an inlet for waste to be put in
2) an outlet for digested material to be removed
3) an outlet so biogas can be piped to where it is needed

Question 4

What are the four factors to consider when building a biogas generator?

Answer 4

1) COST - continuous are more expensive than batch, as material and waste are mechanically pumped in and out
2) CONVINIENCE - batch are less convenient as they have to be continually loaded, emptied and cleaned
3) EFFICIENCY - gas is produced quickly at around 35C, lower and the gas production will be slower, they need to be insulated, and have no leaks
4) POSITION - the waste will smell during delivery, so the generators should be away from home, it also needs to be fairly close to the waste source

Question 5

What are the economic effects of using biofuels? (2 points)

Answer 5

1) the raw material is cheap and readily available

2) digested material is a better fertiliser so more crops can be grown

Question 6

What are the environmental effects of using biofuels?

Answer 6

1) it is carbon neutral
2) doesn’t produce sulfur dioxide or nitrogen oxides, so there is less acid rain
3) no methane is released
4) stops waste, reduces it causing disease and pollution to water supplies