Biofuels

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Biofuels

• Noadswood Science, 2012

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Biofuels

• To understand how biofuels are produced

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Fossil Fuels

• Fossil fuels are running out, and also have a
  huge variety of problems associated with them,
  especially the release of carbon dioxide which
  contributes to global warming

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Global Warming
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Ethanol

• Ethanol is the type of alcohol found in alcoholic
  drinks such as wine and beer
• Ethanol is also useful as a fuel for use in
  cars and other vehicles, it is usually mixed with
  petrol

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Ethanol

• Ethanol can be manufactured by reacting ethene
  (from cracking crude oil) with steam phosphoric
  acid is used as a catalyst -
• Ethene Steam ? Ethanol
• C2H4 H2O? C2H5OH
• In the reaction ethanol is the only product the
  process is continuous as long as ethene and steam
  are fed into one end of the reaction vessel,
  ethanol will be produced
• These features make it an efficient process, but
  as ethene is made from crude oil, which is a
  non-renewable resource, it cannot be replaced
  once it is used up and it will run out one day

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Ethanol Fermentation

• Ethanol can also be made via fermentation sugar
  from plant material is converted into ethanol and
  carbon dioxide
• Enzymes found in single-celled fungi (yeast) are
  the natural catalysts that can make this process
  happen (this is a renewable resource) -
• C6H12O6 ? 2C2H5OH 2CO2

• More than 90 of the worlds ethanol is made by
  fermentation

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Fuels

• It is possible to make fuel for vehicles using
  vegetable oils biodiesel is the name given to
  any fuel made from vegetable oils (and they can
  be added to any diesel engine)

• Biodiesel is made by treating vegetable oils to
  remove some unwanted chemical during production
  other useful products form, including a solid
  waste material which can be used as cattle feed
  and glycerine (used in soap manufacture)

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Biogas

• Biogas is made by anaerobic fermentation of waste
  materials it is about 70 methane and 30
  carbon dioxide
• Many different microorganisms are used in biogas
  production, fermenting plant and animal waste
  (containing carbohydrates) and sewage waste
• Currently biogas cannot be stored as a liquid
  (too high a pressure is needed) so must be used
  immediately for heating / cooking / lighting etc

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Advantages

• Biodiesel is a very clean fuel it also breaks
  down about five times faster than conventional
  crude oil diesel, advantageous if spilt
• It also burns much more cleanly, making far less
  sulfur dioxide and other pollutants
• It also has a major atmospheric advantage as
  crops are used to make the fuel it is carbon
  neutral (all the carbon released by the fuel
  burning was originally absorbed by the plant from
  the atmosphere in the first place)
• Biodiesel therefore makes little contribution to
  the greenhouse gases in the atmosphere

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Recycled

• In an ideal situation biofuels could be carbon
  neutral

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Disadvantages

• Biodiesel is however not without is problems
• There are costs related to its production
  machinery which harvests this biodiesel requires
  fuel itself, so this counts to the atmospheric
  cost
• It also requires crops ethical issues arise
  over using crops for fuel when famine is still
  widespread throughout the world
• There is also a great amount of financial reward
  to producing biodiesel areas of tropical
  rainforest are being cleared in huge amounts to
  grow this money-making crop, leaving vast areas
  having their natural flora and fauna destroyed
  forever