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- What is Anaerobic Digestion?
- Benefits
- Production
- The Environmental Transformation Fund
- What the UK Food and Drink Industry is doing
- The Involvement of Local Authorities
- Developing a Market for Digestate
What is Anaerobic Digestion?
Anaerobic Digestion (AD) is the process that causes the breakdown of biodegradable waste, such as food waste, to produce biogas that can be used to generate electricity and heat or fuels for transportation.
As well as producing biogas AD produces solid and liquid residue, called digestate. This can be used as a soil conditioner to fertilise land.
The benefits of Anaerobic Digestion
There are a number of advantages to using AD. Primarily it produces renewable energy from a feedstock that was previously unharnessed and contributes to climate change through methane production in landfill.
As well as reducing the production on powerful greenhouse gases (GHG) and waste management problems, it can also reduce freshwater pollution from organic wastes, increase fuel security and self-sufficiency and reduce dependence on chemical fertilisers.
The Waste Strategy for England report, published in May 2007, strongly supported using AD to treat food waste. The report recognised that ‘AD has significant environmental benefits over other options for food waste’ and states: ‘The Government wishes to encourage more consideration of the use of AD both by businesses, including in the food and drink sector, and local authorities.’
Anaerobic Digestion Production
Currently there are a relatively low number of AD plants within the UK compared to other European countries. According to the Royal Institution of Chartered Surveyors there are a number of farm co-operative AD plants producing electricity and heating for villages in Denmark. In Sweden biogas plants have been built to produce vehicle fuel, which has resulted in fleets of town buses running on biogas. In Germany and Austria, there are several thousand on-farm digesters treating manure, energy crops and restaurant waste to produce electricity.
AD is also widespread in less developed parts of the world. India and Thailand has several thousand small scale plants - simple home and farm-based AD systems offer the potential for cheap, low cost decentralised energy.
However, recently within the UK there has been a large increase in interest in the commercial use of AD from both industry and government.
The Environmental Transformation Fund
The Environmental Transformation Fund (ETF) is a new government initiative to speed up the development of low carbon and energy efficient technologies in the UK. The fund formally began operating in April 2008, and will be jointly administered by Defra and the Department for Business, Enterprise and Regulatory Reform (BERR).
On 21st February 2008, Hilary Benn, the Secretary of State for Environment, Food & Rural Affairs, announced the first set of new schemes to be funded from the ETF. One of these was to give ‘around £10m over three years for projects that demonstrate the potential of anaerobic digestion technologies at commercial scale.’ (Source: Defra)
What the UK Food and Drink Industry is doing
With many UK manufacturers and retailers aiming to reduce the amount of biodegradable waste that they produce, AD offers a possible solution. One manufacturer has already developed a biogas lagoon - this converts degradable material in wastewater to biogas which can then be used to generate 10% of the plant’s electricity.
One of the UK’s major retailers has pledged that by 2012 through ‘working in partnership’ they aim to ‘build and operate anaerobic digestion facilities to generate renewable energy.’
The Involvement of Local Authorities
WRAP (Waste and Resources Action Programme) is promoting the use of AD to councils across the UK as a means of reducing GHG emissions, improving water conservation, dealing with food waste and reducing the amount of waste sent to landfill.
WRAP is running trials in 17 local authorities across England to identify the most practical and effective ‘food waste collection services to help determine the best way of diverting this waste from landfill.’ They believe that if all the UK’s food waste was sent to anaerobic digestion it would provide 2.09TW of power – almost enough to power Glasgow and Edinburgh.
Developing a Market for Digestate
WRAP and the Environment Agency, working with the Composting Association and the agricultural industry have been asked by Defra to develop a standard and protocol for digestate to help build a market.
They have developed a Quality Protocol: ‘This Quality Protocol could make it easier to collect, store, transport and re-use this biodegradable waste, saving businesses time and money and helping the farming community to diversify. It should stimulate the market for the use of anaerobic digestate products as a fertiliser, soil conditioner and a material in land restoration and reduce the amount of organic waste being sent to landfill.’ (Source: Environment Agency)
An online mapping tool showing the UK's current food waste AD and in-vessel composting processing facilities is available to view on the following link: Mapping tool
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