In I/GCSE Biology, biogas is a flammable mixture of gases formed when bacteria break down plant material or the waste products of animals in aerobic conditions. It is mainly Methane but the composition varies, because it depends on what is put into the generator and which bacteria are present.
- Millions of tones of faeces and urine are made by animals like cows, sheep, pigs and humans. 🐿️🐶🚶♂️
- in many places, plant material grows very rapidly. 🌿🌱🌵
Both the plant material and the animal waste contain carbohydrates. They make up a potentially huge energy resource.
The bacteria in biogas production work best at about 30 degrees Celsius. This means biogas generators work best in hot countries. However the process generates heat (The reactions are Exothermic). This means that if the biogas generators are provided with heat to start with, and are well insulated, they can work anywhere. You can also use the waste from the generators as a fertiliser. What you put into a small generator has a big effect on what comes out. Many different organisms are involved in the breakdown of material in biogas production.
Composition of biogas:
- Methane- 50%-80%
- Carbon Dioxide- 15%- 45%
- Water- 5%
- Hydrogen- 0%-1%
- Hydrogen Sulfide- 0%-3%
In tropical countries plants grow fast. Sugar can has a juice which is very high in carbohydrates, particularly Sucrose. In I/GCSE Biology, we can break the starch in maize kernels down into Glucose using the enzyme Carbohydrase.
Ethanol Based Fuels
If sugar rich products from cane and maize are fermented Anaerobically with yeast, the sugars are broken down to give ethanol and water. This ethanol can be used as fuel in a car.
👍👍 Advantages of Ethanol:
- Does not produce toxic gases
- Can be mixed with petrol to produce Gasohol
- Is Carbon Neutral- produces no overall increase in CO2 levels
👎👎 Disadvantages of Ethanol
- Requires lots of plant material to produce ethanol
- Needs research to be sustainable on a large scale
That's the end of the topic!
Drafted by Joey (Biology)