1. 1
   A bus company is trialling a hydrogen-oxygen fuel cell system to power the electric motor of one of its buses, comparing it with buses that use conventional diesel engines that burn hydrocarbon fuel.

   (a)

   A bus company is testing a hydrogen-oxygen fuel cell to power an electric motor in one of its buses. What is the only waste product formed when the fuel cell reacts hydrogen with oxygen?

   [1 mark]

   • ACarbon dioxide
   • BWater
   • CCarbon monoxide
   • DSulfur dioxide

   (b)

   What must be supplied to the fuel cell continuously for it to keep producing electricity?

   [1 mark]

   • AHydrogen and oxygen
   • BDiesel and air
   • CCarbon and oxygen
   • DOnly electricity from the bus battery

   (c)

   State one advantage of using a hydrogen fuel cell bus compared with a diesel bus, and one disadvantage relating to how hydrogen fuel is stored or produced.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A car manufacturer is comparing two possible uses of hydrogen fuel: burning it directly in a modified combustion engine, versus using it in a hydrogen-oxygen fuel cell to generate electricity for an electric motor.

   (a)

   A car manufacturer is comparing burning hydrogen directly in a combustion engine with using hydrogen in a fuel cell to generate electricity for an electric motor. Which statement about directly combusting hydrogen is correct?

   [1 mark]

   • ACombusting hydrogen produces carbon dioxide as well as water
   • BCombusting hydrogen produces no products at all
   • CCombusting hydrogen can produce oxides of nitrogen due to the high temperatures reached, as well as water
   • DCombusting hydrogen is more energy-efficient than using a fuel cell

   (b)

   Which of these is a genuine advantage of using a hydrogen fuel cell rather than directly combusting hydrogen?

   [1 mark]

   • AA fuel cell produces no water at all
   • BA fuel cell produces carbon dioxide instead of water
   • CA fuel cell does not require any hydrogen to be supplied
   • DA fuel cell avoids the high combustion temperatures that can produce oxides of nitrogen

   (c)

   Explain why using a hydrogen fuel cell to power an electric motor is generally considered a cleaner option than burning hydrogen directly in a combustion engine.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A logistics company that currently uses diesel delivery vans is investigating whether converting to hydrogen fuel cell vans would be a practical and environmentally beneficial choice for its fleet.

   (a)

   A logistics company is deciding whether to convert its delivery vans to hydrogen fuel cells or to keep using diesel engines. Describe two practical challenges the company would face in storing and supplying hydrogen fuel for its vans.

   [3 marks]

   (b)

   Evaluate whether converting the delivery fleet to hydrogen fuel cell vans would reduce the company's overall environmental impact, considering both the fuel cell vans themselves and how the hydrogen fuel is produced.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A government energy agency is reviewing whether to fund an expansion of hydrogen fuel cell buses and infrastructure across the country's public transport network, comparing this option with continuing to use conventional diesel-powered buses.

   (a)

   A government energy agency is deciding whether to invest in expanding hydrogen fuel cell infrastructure for public transport. Discuss the advantages and disadvantages of hydrogen fuel cells compared with conventional diesel engines, covering emissions, energy efficiency, fuel storage and infrastructure, to help inform this decision.

   [6 marks]

   (b)

   Evaluate whether public transport based on hydrogen fuel cells is likely to be more sustainable in the long term than continuing with diesel buses, taking into account how hydrogen is produced and the lifespan of the necessary infrastructure.

   [6 marks]

   Total for question 4: 12 marks

End of questions