Chapter 1B - Biofuels

• renewable energy source • sourced directly from organic matter e.g. sugarcane, soyabeans, wheat or vegetable oils • biogas, bioethanol and biodiesel

Capable of being replaced by natural processes within a relatively short period of time

• formed when organic matter (waste) decays in anaerobic environments • generated by action of micro-organisms (bacteria) on organic molecules • composition: 50-85% methane & 20-25% CO₂

• main biofuel in transportation industry • has same chemical structure as ethanol

blend of 10% bioethanol and 90% petrol - common fuel available in Aus

• anaerobic fermentation of glucose in organic matter (biomass) by yeast microorganism • C₆H₁₂O₆(aq) → 2 C₂H₅OH(aq) + 2 CO₂ (g) • produced in solution • purified via distillation to remove water & produce pure ethanol in liquid form • temperature of >78 degrees required • C₂H₅OH(aq)→ C₂H₅OH(l)

• diesel alternative made from animal fats/ plant oils in transesterification reactions (condensation) • fats/oils made from triglyceride compounds • molecules are called methyl esters

• methanol + long chain fatty acid (carboxylic acid) • triglycerides react w/ an alcohol to produce three molecules of biodiesel and glycerol

• said to be carbon-neutral • CO₂ absorbed by plants during photosynthesis = CO₂ released when fuel combusted • in reality, not completely carbon-neutral because of production processes

• limited food/water supplies so biofuel production shouldn’t reduce amount of food for growing population • to reduce greenhouse gas emissions significantly, vast amounts of land required to grow crops • use of energy (fossil fuels) in production should be minimised - improved efficiency