DF 11: Other Fuels Flashcards
Why do we need fuels of the future?
Fuels of the future should reduce emissions, pollution and be much more economical and reduce global warming.
What is the main alternative to the use of fossil fuels?
Biofuels
What are biofuels?
Biofuels are fuels derived from renewable plant and animal material.
What are the main biofuels that scientists are working on?
Ethanol, biodiesel and biogas
How is ethanol made?
Bioethanol is made by the fermentation process of carbohydrate crops such as sugar cane
What are the advantages of using bioethanol?
Bioethanol is said to be carbon neutral, this is because the carbon dioxide produced in the fermentation and combusting of the ethanol matches the carbon dioxide absorbed in growing the plant (such as sugar cane)
What are the disadvantages of bioethanol?
One of the main disadvantages of bioethanol is that a huge amount of land is required to grow the amount of crops needed for the fuel, this land could be used for other purposes such as food
Why is growing crops for bioethanol a problem in developing countries?
This is a problem because developed countries such as the UK will create a huge demand as they try to find fossil fuel alternatives. Developing countries may see this as a way of getting money, which means land that could be used for growing crops would be lost :(
How is biodiesel made?
Biodiesel is made by chemically reducing fats and oils with an alcohol producing fatty acids and esters
What is the process of biodiesel manufacturing called?
Trans-esterification
What are the advantages of using biodiesel over diesel?
- Biodiesel can be made from waste oil rather than using fossil fuelled based oil, which would only go to waste in landfills (Bio gas also has this advantage)
- It is carbon neutral
- It is biodegradable if spilled
- It contains virtually no sulphur so it reduces oxides of sulphur in the emissions which can cause problems such as acid rain
- It produces less particulates, carbon monoxide and hydrocarbons than petrol and diesel
What are the disadvantages of using biodiesel?
The use of biodiesel produces more nitrogen oxides than conventional fossil fuels
What is another problem with biofuels?
One problem with switching from fossil fuels to biofuels in transport is that petrol car engines would have to be modified to use fuels with high ethanol concentrations = Lots of money
Why are there negatives associated with fuels that are said to be carbon neutral?
There are negatives because fossil fuels are still used in the production of fuels that are carbon neutral such as in the factories that make them and in the lorry’s that transport them.
How is biogas made?
Biogas is produced by the breakdown of organic waste matter
Name the other main potential fuel of the future (its a gas)
Hydrogen
How is hydrogen produced?
Hydrogen can be produced by the electrolysis of sea water
When combusted, what does hydrogen produce?
Just water
What are the advantages of using hydrogen?
- It is renewable and can be made by the electrolysis of water
- It can be stored and sent down pipelines (in much the same way that methane is)
- It can be used in internal combustion engines or in a fuel cell to generate electricity
- It produces no carbon dioxide, carbon monoxide or hydrocarbons when combusted
What are the disadvantages of using hydrogen?
- It is less energy dense than petrol - so it doesn’t release as much energy per gram as petrol
- Oxides of nitrogen are still produced at the high temperatures a hydrogen internal combustion engine runs at
- Its production from water often depends on the use of electricity from fossil fuel power stations
How can hydrogen be used?
Hydrogen can either be burned in a modified engine, or used in a fuel cell, (a fuel cell converts hydrogen an oxygen into water, and this chemical process produces electricity)
What is a problem of obtaining hydrogen?
It takes energy to extract hydrogen from water/seawater
What are the difficulties associated with transporting and storing hydrogen?
Hydrogen is highly flammable and it has to be liquified due to the low energy to volume ratio of hydrogen gas. This means building a whole new infrastructure (Chemical plants to produce the hydrogen fuel)
