3.2.1  Introduction

• A biofuel is a gas, solid or liquid fuel that has been produced from a recently living organism or its metabolic by-product.
  
  
• Biofuels used in vehicles are usually in either a liquid or gas form.
  
  
• Sources of biofuels include sugar cane/beet, a range of vegetable oils, algae, animal fats and sewage.
  
  
• The two main “first-generation” biofuels have been bio-ethanol and bio-diesel. These were made mainly from vegetable oils, starch and sugar.
  
  
• More recently “second-generation” biofuels are being produced using “biomass to liquid” technology, including biomethanol, biohydrogen, HTU diesel and Fischer-Tropsch diesel. 
  
  
• Early users of bio-ethanol have included Nickolaus Otto (for combustion engines he built in the 1860s) and Henry Ford (originally for his famous Model T car in the early 1900s).
  
  
• In the 1890s Rudolf Diesel conceived his diesel engine to run on peanut oil.