The UK is obliged under the revised EU Waste Framework Directive to apply the waste hierarchy. This ranks waste management options in order of environmental preference and the first priority is waste reduction. Recovering energy from waste is only appropriate for waste that cannot be prevented, reused or recycled with less greenhouse gas emitted. Energy recovery can be a sustainable option for waste that would otherwise go to landfill and create landfill methane emissions. Direct combustion (incineration) of dry biomass The heat generated by the following wastes can be used directly to warm homes and buildings or to generate electricity using a steam turbine, or both, through combined heat and power systems: direct combustion (incineration) of dry biomass waste such as wood waste, straw and poultry litter the biomass part of municipal waste some commercial and industrial wastes some construction and demolition wastes Where waste is combusted in a combined heat and power unit, it is possible to produce both heat and power at greater efficiencies. Combustion of waste-derived fuel The methane produced from landfill (landfill gas) is a waste-derived fuel. It can be used in the same way as for combustion plants or it can be injected into the national gas grid. Waste derived fuel is also referred to as Solid Recovered Fuel (SRF) or Refuse Derived Fuel (RDF). Anaerobic digestion Anaerobic digestion (AD) is a natural process in which micro-organisms break down the organic matter found in wet biomass waste (such as sewage sludge, animal manure and slurry and waste food) in the absence of oxygen, to produce biogas (mainly a mixture of around 60% methane and 40% carbon dioxide) and digestate (a nitrogen rich fertiliser). The biogas can be burned directly in a gas boiler to produce heat or burnt in a combined heat and power (CHP) unit to produce heat and electricity. Alternatively, the biogas can be cleaned to remove the carbon dioxide and other substances, to produce biomethane. This can be injected into the national gas grid to be used in the same way as natural gas, or used as a vehicle fuel. The National Non-food Crops Centre (NNFCC) runs the government’s Anaerobic Digestion Portal - a gateway to information on anaerobic digestion, biogas and digestate. Published 22 January 2013 Department for Environment, Food & Rural Affairs Department of Energy & Climate Change
Posted on: Sat, 22 Jun 2013 22:07:34 +0000
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