When bacteria break down waste materials from plants or animals in anaerobic conditions.
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What is biogas?
Mainly made of methane | 70% methane, 30% carbon dioxide | made by bacteria in a digester | flammable | explosive when contains around 10% methane.
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How is methane produced?
It is produced when rubbish decays underground on a landfill site and when sewage decomposes.
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How are commercial quantities of methane produced?
In biogas generators | the bacteria performs best at around 30 degrees celsius | any solid waste left over makes a great fertiliser.
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What are biofuels?
They are renewable fuels made from plant or animal products.
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What alternatives are there instead of fossil fuels?
There is a move towards growing plant material such as maize, which can be converted into methanol.
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What breaks down starch in maize?
The starch in maize can be broken down by carbohydrase enzymes in bacteria
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How else is bioethanol made?
The resulting sugars from breaking down the starch can be fermented anaerobically to produce ethanol | the water is then removed by distillation to produce a usable fuel.
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How does using bioethanol bring us closer to being carbon-neutral?
The amount of carbon dioxide produced when the fuel is burned is offset by the carbon dioxide taken in by the original plants when they photosynthesise.
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Biogas and biofuels are made by..
processing plant materials.
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Bioethanol is made by..
using enzymes in bacteria to break down starch in crops.
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Biogas is made by..
anaerobic breakdown of sewage or organic waste.
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What is biomass?
living or recently-dead material | a store of energy | energy can be transferred from biomass.
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Other cards in this set
Card 2
Front
What is biogas?
Back
Mainly made of methane | 70% methane, 30% carbon dioxide | made by bacteria in a digester | flammable | explosive when contains around 10% methane.
Card 3
Front
How is methane produced?
Back
Card 4
Front
How are commercial quantities of methane produced?
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