Biofuels Flashcards
What is a biofuel?
Fuel produced over a short period of time from biomass (or its refined products)
What has biofuel production historically been driven by?
Economics.
e.g. tax on alcohol in the US meant people did not buy ethanol fuel for cars.
How many years worth of oil, gas and coal are left?
~15 years of oil and gas
~140 years of coal
What is the potential of biofuels and what are the alternatives to fossil fuels?
They can exist in each energy state
Coal: biomass pellets
Oil, petrol: bioethanol, biodiesal
Gas: biogas
How much energy is in jet fuel and a lithium ion battery?
Jet fuel: 43MJ/Kg
lithium ion battery: 0.72MJ/Kg
What are the biofuel generations and what are we currently on?
Currently: 1st gen
Future: 2nd, 3rd, 4th gen
What are 1st generation biofuels?
Bioethanol
Biodiesel
What is bioethanol?
Made by fermentation of sugars and starches e.g. maize and sugarcane.
Can be used as vehicle fuel in its pure form (E10) or can be added to petrol.
What is biodiesel?
Made by transesterification process from fats and oils from plants.
Can be used as vehicle fuel in its pure form (B100) or added to diesel.
Why are bioethanol and biodiesel blended into fuels?
- Bioethanol increases octane rating
- Biodiesel increases cetane rating
- Reduces pollutants
- Bioethanol is corrosive so hard to transport
- Biodiesel is a solvent and coagulates at low temperatures
What are the carbon costs of bioethanol?
- Fermentation
- Distillation
- Dehydration
How much maize was used for ethanol production in 2008?
30.2%
Why is it difficult to change the amount of maize used for biofuel production?
Changing proportion has a huge impact on food prices.
Why can some biofuels be worse than fossil fuels and which ones?
With land use change considered, some biofuels are worse than fossil fuels.
e.g. molasses, soybean, wheat
What is 2nd generation biofuel?
- Cellulose fuel
- Made from non-food crop biomass
- Not as much fertiliser is needed, but needs huge investment to be viable.
