DF11- Other Fuels Flashcards
What are biofuels?
Fuels derived from renewable plant and animal materials
How is ethanol made for use as a fuel?
Fermentation of carbohydrate crops like sugar cane
Why can’t cars run on 100% ethanol fuel?
It is too volatile
Why is ethanol as a biofuel said to be ‘carbon neutral’?
- CO2 produced in fermentation and burning of ethanol is equal to amount of ethanol absorbed in growing plant
Why are there ethical issues surrounding the use of ethanol as a biofuel?
- land could be used to grow crops for food
- energy is used to produce and distribute ethanol which produces CO2
How is biodiesel made and what is the process called?
Chemically reacting fats and oils with an alcohol to produce fatty acid esters
- called trans-esterification
What are the advantages of biodiesel?
- can be made using waste oil
- is carbon neutral
- vehicles can be run on pure biodiesel
- biodegradable
- virtually no sulphur, reduces sulphur oxide emissions
- produces less particulates, carbon monoxide and hydrocarbons than petrol and diesel
What are the disadvantages of biodiesel?
- produces more nitrogen oxides than fossil fuels
What are the advantages of using hydrogen as a fuel?
- renewable
- can be made by electrolysis of water
- can be used in internal combustion engines or in fuel cells
- produces no CO2, CO or hydrocarbons when burnt
What are the disadvantages of using hydrogen as a fuel?
- its production from water usually depends on use of energy from fossil fuels
- less energy dense than petrol
- nitrogen oxides are still produced
