B6d: Biofuels

With problems of declining stocks of fossil fuels and long term problems of nuclear energy, many countries are developing cleaner fuels which need only simple technology. Many of these processes involve the use of microorganisms

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Explain how a plant might produce biomass.
Plants use light energy from the Sun for photosynthesis. This process makes food for the plants, which allows them to grow. The plants may produce biomass - materials that can be used as fuels.
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Give three examples of fuels from biomass.
Alcohol, biogas and wood.
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What can alcohol be made from?
Yeast.
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What can alcohol be used as? How?
A biofuel by mixing with petrol.
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Why is biogas an important energy resource in certain remote parts of the world lacking a mains electricity supply or mains sewage system?
It can be burned to generate electricity and to produce hot water and steam for heating systems and used as a fuel for vehicles.
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Where does the rotting of organic material such as dead plants and animal waste occur?(3)
In marshes, septic tanks and animal digestive systems
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What does the rotting of organic material such as dead plants and animal waste produce?
A mixture of gases including methane.
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What is the rotting of organic material such as dead plants and animal waste caused by?
The action of bacteria.
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How can biogas be produced on a large scale?
By a digestor
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Why is methane being released from landfill sites dangerous?
It can burn or explode preventing use of the site for many years.
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What is a mixture of petrol and alcohol called?
A gasohol.
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What is gasohol used for?
Used for cars in countries such as Brazil.
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Where is gasohol more economically viable? Explain.
In countries which grow a lot of sugar cane and have little or no crude oil reserves of their own. Brazil has relatively small oil reserves, but plenty of waste from its sugar industry – and this can be used in fermentation to make ethanol.
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What does biogas contain?
About 70% methane, about 30% carbon dioxide, and traces of nitrogen, hydrogen and hydrogen sulfide.
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Talk about what a digester does.
Plant/animal waste's added.Air's kept out 2 ensure bacteria inside respires anaerobically.Industrial digesters are often underground 2 help maintain a constant temp.Waste may be added continuously&biogas&remaining solids may be removed continuously 2
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Describe how biogas production is affected by temperature.
The temperature is kept at a constant warm temperature (30-40 degrees celsius) This is the optimum temperature for the bacteria's respiration. Any cooler and the bacteria don't produce biogas as fast. Any hotter and the bacteria will be killed.
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If biogas contains more than 50% methane, what can we do?
Burn it in a controlled way.
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If biogas contains less than 10% methane, what can happen?
It can explode, as it is explosive.
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What is biogas a 'cleaner' fuel than? Why? What is the disadvantage of biogas?
Petrol and Diesel because it releases fewer particulates when burnt. However, it does not contain as much energy as natural gas.
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What are the two different methods of transferring energy from biomass?
Burning fast growing trees, and fermenting biomass using bacteria or yeast.
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Give three advantage of using biofuels.
They're alternative sources to fossil fuels, there's no increase in greenhouse gas levels and no particulates are produced
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Under what circumstances does the burning of biofuels does not cause a net increase in greenhouse gas levels?
If they're being burnt at the same rate as the biomass is being produced and if areas of land are not cleared of other vegetation in order to grow crops for biofuels.
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In some areas, what is the use of large areas of land to produce biofuels resulting in? (2)
Loss of habitat and the extinction of some species of animals and plants.
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Other cards in this set

Card 2

Front

Give three examples of fuels from biomass.

Back

Alcohol, biogas and wood.

Card 3

Front

What can alcohol be made from?

Back

Preview of the front of card 3

Card 4

Front

What can alcohol be used as? How?

Back

Preview of the front of card 4

Card 5

Front

Why is biogas an important energy resource in certain remote parts of the world lacking a mains electricity supply or mains sewage system?

Back

Preview of the front of card 5
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