Pollution from cars: alternative fuels

Is it sustainable?

• No, crude oil is running out

Benefits:

• Less CO produced than from a petrol engine
• Already sold at petrol stations

Risks:

• Produces more NOx and particulates than a petrol engine; particulates can irritate lungs

Is it sustainable?

• No, crude oil is running out

Benefits:

• Less CO, CO2, CxHy and NOx produced than from a petrol engine
• Petrol engines are easily converted

Risks:

• Needs to be stored under pressure, so that it is a liquid

Is it sustainable?

• Possibly not; large amounts of energy needed for cultivating sugar cane for fermentation

Benefits:

• Less CO, SO2 and NOx produced than from a car engine
• Ethanol has a high octane number
• Sugar cane absorbs CO2 in growth

Risks:

• Highly flammable

Is it sustainable?

• Can be made from waste plant and animal oils and fats, so it is renewable, but fossil fuels may be used as an energy source in production

Benefits:

• Living things have absorbed CO2
• It is biodegradable
• Less CO, CxHy, SO2 and particulates produced than from a diesel engine

Risks:

• NOx emissions higher than a diesel engine

Is it sustainable?

• Only if the electricity needed for electrolysis of water is from a renewable source, such as solar cells

Benefits:

• Water is the only product of combustion

Risks:

• Highly flammable
• High pressure fuel tank is needed to store it as a liquid