Biochemical Fuels

  • Also known as biofuels
  • Are derived from organic matter such as sugarcane, vegetable oil and waste
  • They are more environmentally friendly than fossil fuels as most produce little or no carbon dioxide/other greenhouse gases
  • Three types that you should be familiar with: bioethanol, biogas and biodiesel


  • The ethanol here is produced from a fermentation of glucose.
  • Know the fermentation reaction well – it is listed as key knowledge in study design!
  • Bioethanol is currently used to power vehicles. The fuel E10 contains a blend of ethanol (10%) along with normal unleaded fuel.
  • One of considerations that needs to be taken into account when using ethanol as a fuel is food production. Understand, that the glucose used for the fermentation is obtained mainly from sugarcane, which is a product that we use as food (sugar for example). Therefore, if we start using the sugarcane as fuel then there may be less sugarcane available as a source of food.


  • Mixture of esters produced from a reaction between vegetable oil and an alcohol e.g. methanol.
  • Remember that vegetable oil used here is a triglyceride.
  • The produce the biodiesel:
    • The triglyceride (vegetable oil) is hydrolysed (heating) with methanol and potassium hydroxide solution.
    • The potassium hydroxide solution is a catalyst in this reaction. The end product is that the triglyceride breaks down to three ‘fatty acid’ molecules, plus glycerol.
    • The fatty acid produce will react with the methanol to produce the ester (biodiesel).


  • Produced via the fermentation of organic matter (mainly vegetable waste or manure)
  • Gas produced is generally methane via bacteria breaking the the organic matter
  • Even though in the production of biogas, carbon dioxide is produced the whole process is carbon neutral, because the carbon dioxide being produced here has been derived from plant material that originally used the carbon dioxide for photosynthesis.
  • The biogas produced can be used for cooking, lighting, and other energy needs