Choosing fuels

Question 1

List three types of fuels that can be used for cars

Answer 1

petrol
diesel
hydrogen

Question 2

types of fossil fuels and their uses

Answer 2

petrol (cars)
diesel oil (some cars and trains)
fuel oil (large ships and some power stations)

from natural gas:
methane (domestic cooking and heating)

Question 3

non-renewable resources

Answer 3

resources used up faster than they are made

e.g. crude oil and natural gas take millions of years to form but are being used up very quickly

Question 4

manufacture and use of hydrogen as a fuel

Answer 4

combustion of hydrogen produces only water vapour:
2H2 + O2 -> 2H2O

manufactured by:
-electrolysis of water
-cracking of oil fractions
-reaction of natural gas with steam
(CH4 + 2H2O -> CO2 + 4H2)

Question 5

advantages and disadvantages of petrol

Answer 5

advantages:

• burns easily
• does not produce ash
• releases more energy per kg when burnt than coal or wood
• is liquid and is easy to store and transport

disadvantages:

• produces carbon dioxide (a greenhouse gas which contributes to global warming) and carbon monoxide (toxic gas) as well as water
• is a finite fuel and will run out

Question 6

advantages and disadvantages of hydrogen

Answer 6

advantages:

• burns easily
• does not produce ash or smoke
• only produces water
• releases nearly 3x as much energy per kg than petrol

disadvantages:

• is a gas, so is difficult to store at high pressure
• filling stations would need to be adapted for the use of hydrogen in cars
• increased risk of leaks
• technology for hydrogen engines is expensive

Question 7

Describe three features of a good fuel

Answer 7

• burns easily - easy to ignite and stays alight
• no produce soot, smoke, or ash
• release a lot of energy when burnt

(and is easy to safely transport and store)

Question 8

Explain why the combustion of petrol produces carbon dioxide, but the combustion of hydrogen does not

Answer 8

petrol contains hydrocarbons
carbon in the molecules is oxidised to carbon dioxide

hydrogen does not contain carbon/consists only of hydrogen

Question 9

a) Suggest reasons to explain why hydrogen produced from crude oil or natural gas may not be renewable

b) CO2 is a greenhouse gas linked to global warming and climate change
Hydrogen is often regarded as a ‘carbon neutral fuel’, a fuel with production, transport, adn use that have no overall emission of CO2

Suggest reasons to explain why hydrogen may not actually be carbon neutral

Answer 9

a) crude oil and natural gas are non-renewable
they are being used faster than they are formed
as hydrogen is produced from them, it is also non-renewable from those sources

b) CO2 may be produced during the manufacture and transport of the fuel
For example, fossil fiels are used in power stations to generate electricity/to react with steam to make hydrogen
CO2 is also released by vehicles used to transport the fuel