3.3  Hydrogen

• 3.3.1  Vehicle Fuel
  
  
  • Hydrogen, typically stored as a liquid and used as a gas, can be used as a fuel in:
    
    
    • A slightly modified version of the petrol powered internal combustion engine.
      
      
    • A fuel cell (which turns hydrogen into water and then into electricity to drive an electric motor).
      
      
• 3.3.2  Hydrogen Data
  
  
  • Hydrogen (H2) is the most abundant element in the universe. It is designated “atomic number 1”.
    
    
  • At normal atmospheric temperatures and pressures hydrogen is a flammable gas.
    
    
  • It is a solid between absolute zero of minus 273.16 degrees C and its melting point of minus 259.34 degrees C, when it becomes a liquid.
    
    
  • It remains a liquid in the small band of 6.47 degrees C, until it rises to its boiling point of minus 252.87 degrees C. Note: Water has a boiling point of plus 100 degrees C.
    
    
  • It is usually stored as a liquid because when it is converted to gas, hydrogen expands and takes up about 840 times more space.
    
    
  • It is the lightest of the gases. About one-fifteenth the weight of air.
    
    
• 3.3.3  Hydrogen Production  
  
  
  • On our planet hydrogen exists mainly as part of other compounds and has to be extracted from them; such as water, fossil fuels, natural gas and  coal. It is therefore a manufactured fuel.
    
    
  • In 2006 extracting hydrogen consumed about 60% more energy than the resulting hydrogen provided.
    
    
  • Two of the most common ways of producing hydrogen are by steam reforming and electrolysis.
    
    
  • Steam reforming, mainly from natural gas, is currently the most cost effective and hence the most popular method.
    
    
  • Electrolysis, which extracts hydrogen from water, is currently a much more expensive process.
    
    
  • For every one litre of petrol about four times the amount of liquid hydrogen is required to obtain the same amount of energy.
    
    
  • To store liquid hydrogen at between minus 259.34  and minus 252.87 degrees C it must be kept in a pressurised and thermally insulated container.
    
    
  • Due to the very low temperatures involved liquid hydrogen will slowly evaporate from its container.
    
    
• 3.3.4  Cars Using Hydrogen
  
  
  • For cars using hydrogen powered fuel cells see Green Cars, Section 8.
    
    
  • BMW: BMW’s Hydrogen 7 car has an internal combustion engine that can run on petrol or hydrogen. When was it first produced?
    
    
  • The car was powered by a 350 hp (260 kW) 12-cylinder engine. 
    
    
  • Mazda: In 2004 Mazda introduced the RX-4 Hydrogen RE, rotary engined, concept car. It was designed to run on petrol or hydrogen.
    
    
  • The car has a maximum range of 341 miles (546 km) when running on petrol or 62 miles (99 km) when running on hydrogen. 
    
    
  • In March 2006 Mazda started to deliver these cars to customers.
    
    
• 3.3.5  LPG & CNG   

•  Liquid Petroleum Gas (LPG) and Compressed Natural Gas (CNG). Information under preparation.