# Explain why hydrogen-oxygen fuel cells are considered more advantageous than petrol engines for powering vehicles.

> Cambridge International IGCSE Chemistry (0620) — 4.2 Hydrogen-oxygen fuel cells · Explain · 4 marks

> Engineers are designing a new fleet of buses for a city. They must choose between buses powered by petrol engines and buses powered by hydrogen-oxygen fuel cells.

## Mark scheme (4 marks)

1. Fuel cells produce water (vapour) as the only product / no harmful exhaust emissions / no carbon dioxide or carbon monoxide produced
2. Petrol engines release/produce carbon dioxide which contributes to global warming / climate change / greenhouse effect
3. Fuel cells convert chemical energy directly into electrical energy / more efficient energy conversion than petrol engines
4. Hydrogen can be produced from renewable sources / fuel cells operate continuously as long as hydrogen and oxygen are supplied

## Key terms

- [fuel cell](https://www.gradenine.co.uk/glossary/fuel-cell)

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