Biomass is the sum total of the Earth's living matter. It is potentially near carbon neutral if used as a solid, liquid or gaseous fuel. Conversion of biomass to be suitable as a fuel falls into two categories:
• by cultivation of short rotation crops.
There are three main methods of conversion to energy:
• direct combustion
• anaerobic digestion
• extraction of landfill methane.
In direct combustion SRCs provide bulk for burning directly in power plants or co-fired with coal. In anaerobic digestion, wet waste including sewage is fed into a sealed digester. Bacteria break down the biomass to produce a methane-rich gas which can be used to generate combined heat and power. Suitably treated biogas can be introduced into the natural gas pipe network.
Landfill methane is the most abundant source of biogas but reserves are expected to decline rapidly.
Considerable opportunities exist for biofuels to power transport. Brazil has been doing it for decades. A research project funded by Germany is considering the potential of biodiesel and bioethanol to replace petrol products with the aim of producing a 'vibrant biofuels industry'.
One of the most promising routes for the future is a project that involves an enzyme that breaks down straw into its constituent sugars to produce cellulose ethanol. Further distillation produces a product marketed as Ecoethanol.
The 2005 Biomass Task Force anticipates that 1 million ha will be available for biofuels.
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