In 2009, Britain turned 45,000 tonnes of food waste into biogas; the result generated 1.7 MW of renewable electricity for 2,700 homes at Westwood in Northamptonshire

In 2009, Britain turned 45,000 tonnes of food waste into biogas; the result generated 1.7 MW of renewable electricity for 2,700 homes at Westwood in Northamptonshire. The Westwood anaerobic digestion plant near Rushden was opened in June 2009. It processes food waste from households, retailers, supermarkets, food producers and commercial outlets. The facility also produces liquid biofertiliser for farmland. More than 90% of the electricity generated is sold to the National Grid. The plant became part of a wider discussion about using anaerobic digestion to manage organic waste, reduce landfill emissions and produce electricity, heat, fuel and agricultural products from waste.

How the Westwood plant turns food waste into energy?

In 2009, Britain turned 45,000 tonnes of food waste into biogas; the result generated 1.7 MW of renewable electricity for 2,700 homes at Westwood in Northamptonshire. The Westwood plant is located near Rushden in Northamptonshire.


The facility uses anaerobic digestion to process food waste. The process takes place without oxygen. Organic material is placed inside digestion systems where microorganisms break it down.

One of the products of this process is methane-rich biogas. The gas can be used to generate electricity and heat. It can also be processed into biomethane for possible use in the National Gas Grid.

The Westwood facility can process 45,000 tonnes of food waste every year. The waste comes from several sources, including households, commercial outlets, retailers and food producers. The plant receives waste from businesses including Sainsbury’s, Waitrose and Whitbread. The company was also working with 14 local authorities across the country.

Electricity figures from the Westwood project

The plant information gives an electricity output of 1.7 MW of renewable electricity. This was described as enough to supply 2,700 homes. Other project information describes the facility as generating around 2 MW and powering roughly 3,000 homes continually.

These figures represent different estimates used in descriptions of the plant. The specific plant facts state 1.7 MW and 2,700 homes, while the project description gives around 2 MW and nearly 3,000 homes.

More than 90% of the electricity produced is sold to the National Grid. This means the electricity generated from food waste is connected to the wider power system rather than being used only at the plant.

What happens to the remaining material?

Anaerobic digestion does not only produce biogas. The process also produces a material that can be used as fertiliser. The Westwood plant produces about 35,000 tonnes of liquid biofertiliser each year. The material can support about 1,750 acres of growing crop.

This creates another use for the organic material that enters the plant. Instead of sending food waste to landfill, the process produces electricity and a product for agricultural use. The project therefore links waste management with energy production and farming.

Key facts about the Westwood plant:

• The plant opened in June 2009.
• It is located near Rushden, Northamptonshire.
• It processes up to 45,000 tonnes of food waste each year.
• The stated electricity output is 1.7 MW.
• The electricity can supply about 2,700 homes.
• Another description gives around 2 MW and nearly 3,000 homes.
• More than 90% of electricity is sold to the National Grid.
• The plant produces about 35,000 tonnes of liquid biofertiliser each year.
• The biofertiliser can support about 1,750 acres of growing crop.

Why Britain looked at anaerobic digestion?

The Westwood plant was examined as the British Government considered how anaerobic digestion could contribute to renewable energy. Environment Minister Lord Henley visited the plant during a fact-finding trip to Northamptonshire. The visit took place while the Government was preparing an action plan on increasing the use of anaerobic digestion across Britain.

During the visit, Lord Henley saw how supermarket food that could no longer be sold could be processed to generate electricity. The Government was examining how the technology could be expanded and what steps would be required to increase its use.

Lord Henley said food scraps and out-of-date supermarket food could be treated as a resource for energy instead of being sent for disposal. He also said the technology could reduce greenhouse gas emissions. He referred to discussions already held with industry, farmers and the financial sector. Teams at Defra and DECC were working on an action plan.

Government plans included industry and farming

Earlier that month, the Government had held roundtable discussions with representatives from business, farming, the financial sector and the anaerobic digestion industry. The discussions focused on how the technology could be expanded. Defra and DECC were expected to jointly prepare an action plan by the autumn. The plan was intended to examine the economic capacity of the anaerobic digestion industry.

It would also consider steps that the Government and industry could take to increase the use of the technology. The discussions placed food waste, renewable electricity, farming and waste management within the same policy framework.

How anaerobic digestion works?

Anaerobic digestion can use several types of organic waste. These include food waste, farm waste, animal manure and sewage sludge. The material is placed in a system where oxygen is absent. Microorganisms break down the organic matter and produce biogas. The biogas contains methane and can be used in several ways.

Possible uses include:

• Generating electricity.
• Producing heat for homes and businesses.
• Providing energy for industry.
• Producing transport fuel.
• Upgrading biogas into biomethane.
• Potentially supplying biomethane to the National Gas Grid.

The process can be used at different scales. A small system can operate on a farm or at a business that produces large amounts of food waste. Large centralised systems can also process waste from several sources. These facilities can be used at sewage treatment works or for municipal food waste. They can also process manure and slurry from multiple farms.

Food waste and landfill emissions

The use of anaerobic digestion also relates to landfill emissions. When biodegradable waste is sent to landfill, it can produce greenhouse gases as it breaks down. Diverting this material to anaerobic digestion can reduce emissions associated with landfill.

The information provided on the Westwood project states that digesting one tonne of food waste instead of sending it to landfill can save between 0.5 and 1 tonne of CO2 equivalent. This gives waste treatment another role in renewable energy planning. Food waste can become a source of biogas rather than remaining only a disposal problem.

Britain’s wider anaerobic digestion capacity

At the time of the Westwood project, there were around 37 anaerobic digestion plants in the UK using food and farm waste. Around 60 more facilities were planned or under construction.

A further 220 water treatment plants had anaerobic digestion facilities for sewage. The figures showed that anaerobic digestion was being used across different parts of the waste and water sectors. The Government was also considering how this capacity could increase.

How much energy could organic waste provide?

The UK was estimated to produce about 100 million tonnes of food, farm and other organic waste each year. The information stated that this waste could potentially generate up to 7% of the renewable energy required in the UK by 2020.

The Westwood plant provided one example of how this approach could work. It used commercial and household food waste to produce biogas, renewable electricity and liquid biofertiliser. The project also showed that waste from supermarkets and food producers could become part of an energy system.

What the Westwood project showed?

The Westwood anaerobic digestion plant brought together several uses of food waste. Food that could no longer be sold was collected and processed. The digestion process produced methane-rich biogas. The biogas was used to generate renewable electricity. Most of that electricity was supplied to the National Grid.

The process also produced liquid biofertiliser for farmland. The Government's examination of the plant came as officials considered how anaerobic digestion could be expanded across Britain. The wider plans involved Government departments, businesses, farmers, financial organisations and technology experts. The project therefore became an example of how organic waste could be diverted from landfill and used to produce energy and agricultural inputs.