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Analysis: Are we reaching biogas overcapacity in the UK?

Following the news that the UK has now built more than a hundred anaerobic digesters treating food and farm waste, Dr Matthew Aylott of NNFCC looks at the future of the industry and asks whether we are reaching overcapacity.

Date Posted 11 Apr 2013
Story Source Dr Matthew Aylott, NNFCC
Relevant Industries Bioenergy

Anaerobic Digestion Case StudyIn 2009, the UK Government said that anaerobic digestion of food and farm waste could generate up to 20TWh of heat and power by 2020 – this scale of generation would require the construction of more than 1000 anaerobic digesters across the UK. At the time this seemed a long way off, particularly considering the barriers facing the industry.

The news that the UK now has more than 100 anaerobic digesters outside the water industry may still only be a fraction of the infrastructure required, but the achievement is important and will provide greater confidence to those investing in biogas.

UK now has 106 anaerobic digesters

Official figures gathered by NNFCC and WRAP, reveal that the number of AD plants in the UK has nearly doubled since September 2011, when a comprehensive baseline report was published. There are now 106 anaerobic digestion plants outside of the water industry, processing up to 5.1 million tonnes of food and farm waste every year and with an installed electrical capacity of more than 88MWe.

Reaching this landmark figure has been slower than some anticipated and the UK is still a long behind countries like Germany, where there are more than 7000 digesters. But following the delivery of the Government’s AD Strategy and Action Plan in 2010, many of the barriers which had previously held back the industry have been overcome.

Stable support mechanisms are now in place to incentivise anaerobic digestion development and the planning system has been simplified to make it easier for developers. Capital funding is also easier to come by and access to grid connections and markets for digestate have improved considerably.

Nearly half (46) of the AD plants currently in operation are 'community' digesters, where food waste is collected from multiple sources, like supermarkets, hospitality providers and households, to be converted into heat, power and fertiliser. These community digesters have a capacity to treat around 1.8 million tonnes of food waste per year and a potential electrical generating capacity of around 56 MWe. And this is only the tip of the iceberg.

Will demand for municipal waste lead to a new gold rush?

Larger plants are being built to accommodate the increasing demand for food waste treatment solutions, with the average size of planned digesters processing food waste more than doubling from their current size. There are around 200 food waste treatment anaerobic digesters currently going through the planning process, with a combined capacity to treat an extra 7 million tonnes of food waste.

Development is largely focussed on clusters of anaerobic digesters around the major towns and cities. These planned digesters are targeting food waste contracts from consistent waste streams like retail and industrial waste. Current planned development of the food waste anaerobic digestion sector might suggest we are reaching over capacity.

Are we reaching anaerobic digestion overcapacity?

There are approximately 8 million tonnes of business waste suitable for anaerobic digestion and a further 8 million tonnes of household waste which could also be used. Therefore even if all planned digesters were actually built we would only have capacity to treat and process approximately half of the waste we generate.

In reality it is likely that only 70 to 80 per cent of those plants currently going through the planning process will be granted planning permission. Even digesters that gain planning permission face an uphill struggle getting built, owing to financial and contractual issues. Of the 200 food waste plants in development the number of plants that actually get built could be as low as 20 to 30 per cent.

Challenges remain

The increased number of plants will make attractive contracts and waste streams harder to find. There will also be increased competition for waste from in-vessel composters, which can handle mixed food and green waste. Developers will have to start looking at more variable food waste streams such as household food waste and will need to work more closely with local authorities to promote the source segregation of food waste.

Despite the challenges the future of the anaerobic digestion industry remains positive and, beyond food waste, the agricultural sector remains relatively untapped. There are more than 10,000 dairy farms and 4000 pig farms in the UK, generating 90 to 100 million tonnes of manure and slurry every year which could be feedstocks for anaerobic digestion. This may be unfamiliar territory to some anaerobic digester developers but could be a golden opportunity for those looking for new income streams.

By Matthew Aylott

This article first appeared in the 28th March 2013 edition of Recycling & Waste World magazine.

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