What are biofuels derived from?
Renewable plant and animal materials.
What are two examples of biofuel?
Ethanol and biodiesel.
Why can’t ethanol be used alone as a fuel?
Because it is too volatile.
Why is ethanol sometimes said to be carbon neutral?
The carbon dioxide emitted in process of fermentation and burning of ethanol matches with the carbon dioxide absorbed in growing of plant.
What is failed to be accounted when they say ethanol is carbon neutral?
Energy used to produce and distribute the ethanol may have come from fossil fuels which would also produce carbon dioxide.
What is a controversy regarding land use about ethanol?
The land used to grow crops for fermentation of ethanol could be used to produce food instead.
What is biodiesel?
Reacting fats and oil with alcohol to produce fatty acid esters.
What is the process of making biodiesel known as?
Trans-esterification.
What are some advantages of biodiesel over normally diesel?
- It can be made from waste oil instead of fossil fuel based oil.
- It is almost carbon neutral.
- It is biodegradable if spilled.
- It contains virtually no sulfur so reduced sulfur oxides emissions.
- More oxygenated so less incomplete combustion, overall less pollutants produced.
What is a disadvantage of biodiesel?
It produces more nitrogen oxides than conventional fossil fuels.
What is the only product of the combustion of hydrogen?
Water.
What is the equation for the combustion of hydrogen?
2H2(g) + O2(g) → 2H2O(g)
What are some advantages of hydrogen as a fuel?
- It is renewable as hydrogen can be made from the electrolysis of water.
- It can easily be stored and transported through pipelines.
- Good for generating energy.
- Reduces pollutants.
What are some disadvantages of hydrogen as a fuel
- Producing hydrogen from electrolysis of water often require electricity which may be provided by fossil fuel energy.
- It has a lower energy density than petrol.
- Production of nitrogen oxides will still be high.
- It is an explosive gas.
- Hard to store in the car.
