# A renewable energy company is developing a biofuel made from fermented plant material. The biofuel contains ethanol. Explain why ethanol produced from plants may be considered carbon neutral, and describe one limitation of replacing petrol with this biofuel on a large scale.

> OCR A-Level Chemistry B: Salters (H433) — DF Developing fuels · Explain · 5 marks

> Biofuels such as ethanol can be produced by fermenting sugars from crops such as sugar cane. Some scientists argue these fuels are carbon neutral, while others point out practical drawbacks of large-scale use.

## Mark scheme (5 marks)

1. Plants absorb/take in carbon dioxide from the atmosphere during photosynthesis (as they grow)
2. When ethanol/biofuel is burned it releases carbon dioxide back into the atmosphere
3. The CO₂ released on burning equals/is balanced by the CO₂ absorbed during growth, so there is no net increase in atmospheric CO₂
4. A valid limitation stated — e.g. large areas of land/farmland are needed to grow the crops (so less land for food production)
5. Limitation developed/explained — e.g. this could lead to food shortages or destruction of habitats/deforestation

## Key terms

- [carbon neutral](https://www.gradenine.co.uk/glossary/carbon-neutral)
- [biofuel](https://www.gradenine.co.uk/glossary/biofuel)

## Related

- [Revision notes for OCR A-Level Chemistry B: Salters (H433)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-renewable-energy-company-is-developing-e6ba4c0a) · Published by Druglandscape Ltd.