Reactivity 1.3.4

Biofuels

Fuels derived from biological fixation of carbon over a short period of time.

A corn field used for biofuel production

Corn fields (Maize) are a primary source for Bioethanol production.

Carbon Neutrality

Biofuels (like Ethanol from corn) are theoretically carbon neutral.

The Cycle:

Plants absorb $CO_2$ from the air via Photosynthesis ( $6CO_2 \rightarrow C_6H_{12}O_6$ ).
Plants are fermented to make Ethanol.
Ethanol is burned in a car, releasing $CO_2$ .
The released $CO_2$ equals the absorbed $CO_2$ . Net Change = 0?

Deep Think Concept

Reality Check

Why aren't they truly neutral?

Energy is required to plant, fertilize, harvest, transport, and distill the fuel. This energy usually comes from fossil fuels.

Also, land use change (deforestation) to grow fuel crops releases massive amounts of stored carbon.

Putting it into Practice

Demonstrating Carbon Neutrality

Paper 2 Style

Show, using balanced equations, that the production and combustion of bio-ethanol is theoretically carbon neutral.

Practice: Biofuel Ethics

[1 Marks]

Discuss one ethical disadvantage of using food crops (like corn or sugar cane) to produce biofuels.

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