A hospital needs a backup supply of electricity for when the mains supply fails. The hospital is considering three options.
The table shows information about each option.
| Feature | Diesel generator | Hydrogen fuel cell | Rechargeable batteries |
|---|---|---|---|
| Time to start supplying electricity | 10 seconds | 30 seconds | instant |
| Time it can run before refuelling or recharging | 48 hours | 24 hours | 4 hours |
| Substances released during use | carbon dioxide, carbon monoxide, oxides of nitrogen, soot | water only | none |
| Noise | loud | quiet | silent |
| Cost of running for one hour / £ | 60 | 110 | 25 |
| Storage of fuel | diesel is a liquid, easy to store | hydrogen gas stored at high pressure, flammable | not needed |
Explain why the rechargeable batteries can supply electricity for only a limited time before they need recharging.
The fuel cell uses 2.5 kg of hydrogen each hour. Calculate the mass of hydrogen the hospital must store so that the fuel cell can run for 24 hours.
Evaluate the use of each of the three options as the backup electricity supply for the hospital. Use the information in the table and your own knowledge.
38 exam-style questions on Edexcel GCSE Chemistry 6.4 Chemical cells and fuel cells, covering 6.4.1 Chemical cells and fuel cells. Each one has a worked solution and a mark scheme showing where the marks go.