With there being a limit to the carbon reductions achievable from petrol, diesel, CNG and LPG, attention has shifted towards fuels that can be used in ICEs and that have substantially lower CO2 emissions. The most significant developments have been in liquid biofuels: renewable fuels that can be produced by the fermentation of energy crops or from vegetable oils or animal fats. Such fuels can reduce the transport sector's dependence on fossil fuels and potentially achieve major cuts in greenhouse gas emissions, since the crops used are part of the natural carbon cycle.
Biofuels can come from a wide number of sources, and include:
For further information see 'Biofuel types' in Department for Transport, 2012a; U.S. Department of Energy, 2011; 'Methanol' and 'Renewable Natural Gas' in U.S. Department of Energy, 2012; and CPL Press, 2009.
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