Biofuels and Plant oils

Question 1

Use your knowledge explain the environmental benefits of using biodiesel as a sustainable, low pollution fuel. (3 marks)

Answer 1

sustainable:
maximum two from:
- crops (that produce oil) can be grown in most places
- renewable
- use less fossil fuels / diesel
- use (refined) waste oils
low pollution:
maximum two from:
- most emissions are lower or any two named emissions from CO / SO2 / PM10 are lower
- much / lot less SO2 emissions (than the others)
- accept spillages / waste is biodegradable
- less new CO2 or (more) carbon neutral

Question 2

Biodiesel is called a green fuel. This is because the life-cycle emission of carbon dioxide from biodiesel is less than that from fossil diesel. Use your knowledge to explain why biodiesel’s contribution to global warming is considered to be much less than that of fossil diesel. (3 marks)

Answer 2

• plants / photosynthesis use carbon (dioxide) from the air
• biodiesel releases carbon (dioxide) from plants / crops / photosynthesis
• (fossil) diesel releases .locked up. / new carbon (dioxide) / doesn’t absorb CO2 / absorbed it millions of years ago

Question 3

Carbon monoxide can be produced when diesel burns in a car engine. Explain how. (2 marks)

Answer 3

carbon / diesel / it reacts / burns in oxygen / air
limited supply (of oxygen / air)
accept incomplete combustion

Question 4

Evaluate the use of biodiesel compared with fossil diesel as a fuel for cars. Remember to give a conclusion to your evaluation. (5 marks)

Answer 4

any four from:
for biodiesel:
- less global dimming (because fewer carbon particles)
- less acid rain (because less sulfur dioxide)
- renewable resource / sustainable
- use waste vegetable oils / fats
- vegetables / plants absorbed carbon dioxide / carbon neutral
- uses land which could be used to produce food
- third world countries can produce bio diesel
- biodegrades easily
- more NOx released
justified conclusion
accept converse statements for fossil diesel.
ignore cost / ease of manufacture / usage issues
accept fossil fuel / diesel supplies are limited
accept fossil fuel / diesel releases locked up carbon / is not carbon neutral

Question 5

Evaluate the use of plant oils to produce biodiesel. Remember to give a conclusion to your evaluation. (5 marks)

Answer 5

Arguments for biodiesel
max three from:
• sustainable / renewable
• (carbon neutral) absorbs CO2 when growing / during photosynthesis
• burning biodiesel produces low amounts particulates / carbon monoxide
• can use waste vegetable oils / fats (from food industry) or can use waste plant material
• can be used to conserve crude oil (instead of / mixed with petroleum diesel)
• produced by a low energy / temperature process
• biodegrades (easily)
Arguments against biodiesel
max three from:
• creates food shortages
• deforestation to plant more crops leads to loss of habitat / biodiversity or deforestation leads to a reduction in absorption of CO2
• burning biodiesel produces high amounts of nitrogen oxides
• crops takes time to grow
• vast areas of land needed to grow crops
conclusion supported by the argument presented, which must give added value to the points for and against given above