Biofuels

Biofuels are made from biomass (plant or animal material)

An alternative to fossil fuels which are non-renewable

How are biofuels made?

Production of bioethanol

  1. Deconstruction

Breakdown of biomass to increase surface area, for more efficient process, either physically or chemically

  1. Digestion by enzymes

Further exposure to enzymes to break down starch and cellulose. Water is added (hydrolysis)

  1. Ethanol fermentation

Yeast is used to produce large amounts of ethanol that diffuses out of the cells

  1. Purification and dehydration

ethanol is distilled (water removed) so it can be converted to biofuel that is purified and ready to use

Bioethanol - fermentation of plant sugars

Biodiesel - animal fatty acids or vegetable oils

Fossil fuel sustainability

  • non renewable

Fossil fuel source

  • fossilised organic matter over millions of years

Fossil fuel environmental impact

  • high carbon emission

Bio fuel sustainability

  • renewable

Bio fuel source

  • modern crops, plant residue, organic waste, animal by-products

Biofuels environmental impact

  • largely carbon neutral

Implications

Strengths of bio fuels

  • decrease CO2 emissions
  • energy security, renewable and stops reliance on fossil fuels
  • localised energy. decreased international reliance on imports or exports

Weaknesses of bio fuels

  • food vs fuel. Crops need area and so does biofuel, so decrease agricultural food output
  • cost and difficulty of uptake. Relatively expensive to produce.
  • 2nd order environmental impacts, deforestation, NOX emission, decrease genetic diversity of crops.