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Down on the farm the energy plant bubbles

Farm-based anaerobic digestion (AD) can be about more than just slurry tanks and off-specification [?] crops. It is also an opportunity for any business generating organic waste to send it to be treated on the farm. For the farmer, taking in waste presents an opportunity to create a new income stream, and generate more renewable energy and biofertiliser.

Last month, the Anaerobic Digestion and Biogas Association (ADBA) launched a free farmers’ consultancy service. Aimed at UK farmers, growers and land managers, the service will help farming businesses to decide whether AD is a viable option.

AD is an expanding field with new plants in the pipeline. This level of growth creates an exciting marketplace for waste producers because such plants offer competitive prices and can reduce landfill tax obligations. It will take time for newly commissioned AD plants to agree local authority contracts but plants will always need to be supplied with waste, leaving them open to the more flexible and short term agreements offered by the commercial sector.

With the Department for Communities and Local Government’s Weekly Collection Support Scheme – the £250m pot of funding for weekly household waste collections - open for applications, gate fees for landfill increasing, and the Government introducing ever more difficult targets for organics to landfill, businesses producing organic waste will have to be ever more creative in their plans for dealing with it.

The possibility of sending food waste to local AD plants based on farms is a possible model for enterprise in waste treatment infrastructure. A network of on-farm plants taking relatively small amounts from local businesses such as pubs, bars, and restaurants is an interesting scenario for these waste producers who often have limited options for source segregated collections and are not able to build AD plants themselves.

Local authorities and waste management firms running local authority contracts could also benefit from the expansion of on-farm waste treatment. It could also reduce infrastructure and treatment costs, as well as provide more localised treatment options, which reduce vehicle miles. This idea is already being exploited by several plants across the UK.

Bedfordia Farms and Twinwoods AD plant, built and operated in conjunction with BiogenGreenfinch, Lower Reule Bioenergy and Langage Farm AD plant are all examples of plants running on a mixture of local authority MSW, C&I and farm waste.

The Befordia Farms and Twinwoods AD plant was developed in 2005 by the farm- with BiogenGreenfinch - as a means of increasing the viability of its pig farming business. The plant now treats 30,000 tonnes of food waste and 12,000 tonnes of pig slurry each year.

Customers sending their food waste to the Twinwood plant for treatment include several local authorities, including Central Bedfordshire Council, Luton Council, and the London Borough of Ealing, as well as food producers and caterers such as Whitbread, Bakkavor, Birds Eye and Punch Taverns. The resulting mix produces 1.4MW of renewable electricity every year.

On-farm plants treating external waste like this are more complicated than standard farm inputs and farm-based operators need to be aware of these challenges. They can, however, offer significant savings to local authorities and waste managers who choose to send their waste to AD rather than build themselves as they do not have an obvious mechanism for dealing with the digestate biofertiliser produced.

“An AD plant situated on a  farm can be an attractive investment proposition where a competitive advantage can be derived from a strong digestate solution and where its location can offer a lower operational cost base compared to AD plants in urban or industrial locations,” says BiogenGreenfinch chief executive Richard Barker. 

Lower Reule Bioenergy’s 1.3 MW, 30,000 tonne plant in Staffordshire has been in operation since 2010. It currently treats a significant proportion of food waste with only a small amount of cow slurry added to the mixture. Of the food waste accepted, around 50% is from local authorities and 50% is commercial and industrial (C&I) waste.

“The commercial waste we treat is very varied as this is a fast moving market,” says Lower Reule Bioenergy managing director Helen Franklin. “C&I waste producers are looking for very flexible contracts and as more plants come online this has an impact on gate fees. Whereas although the procedure for securing local authority waste contracts is lengthy, the benefits are that you get a fairly long term contract giving you feedstock security for your plant”

Despite the challenges in agreeing contracts Franklin thinks the commercial route is worth it: “The volume of waste available for AD will increase. The DCLG fund for weekly collections is a great thing that will stimulate the diversion of food waste from landfill to AD as more and more kitchen waste is collected separately. The commercial side is harder to predict as these producers are in a position to build plants themselves.”

The Langage Farm AD plant in Devon has capacity to take in 50,000 tonnes of waste a year. It has been designed to treat 12,000 tonnes of externally sourced kitchen waste with the remainder comprising cow slurries and internally generated waste from the Langage Farm dairy factory.

The farm initially explored AD for its biofertiliser by-product as the farm was suffering from decreasing milk yields. Research suggested that this was the result of compacted soil that had a knock on effect on the quality of the grass. In operation since 2010 the food waste it treats is mostly household kitchen waste with small amounts of varying C&I waste including supermarket waste and consignments from factories and local retailers.

“Our waste streams are not just from local enterprise - we have consignments travelling as far as 80 miles. Unfortunately we do not treat any really local household kitchen waste as Plymouth Council has not implemented separate food waste collections. We do receive food waste from Torbay, Torquay and the South Hams areas through Viridor,” says engineering manager Gary Jones.

The Farm has recently partnered with Plymouth based waste collection firm Alpha:Logic and together they have launched Food:Logic. An enterprise that plans to offer small and regular collections of C&I waste to smaller retailers with the organic fraction being sent to Langage farm AD.

“The Food:Logic partnership is a great tool, it markets the farm and the farm’s customers and creates a closed recycling loop,” adds Jones. “The people we are looking to work with are interested not just because of the competitive price we can offer but also because of the added benefits of being associated with the farm. Restaurants and hotels that sell our products are able to say that they are not only environmentally responsible in how they source products but they are also trying to deal with their waste in a sustainable way.”

Alpha Logic director Neil Stallard says, “Clearly, alongside the environmental and financial benefits of participating in the scheme, it will further allow businesses to demonstrate their true commitment to environmental issues.”

Making farming sustainable is integral to encouraging wider economic growth in the UK, meeting climate change targets, improving resource efficiency through the use of biofertiliser and reducing our dependence on fossil fuels. As ever more on-farm plants are built and new companies come into the market the dynamics will change.

Investment in AD plants requires security of feedstock and this is important to consider. Ensuring plants are flexible enough to handle changing situations is therefore important, accepting a mix of waste streams gives these plants the guarantees they need of feedstock from local authority contracts and their own farm waste and allows them to innovate in the field of waste collection from local SMEs and businesses.

New AD enterprise Tamar - launched with the financial banking of The Prince of Wales and retail giant Sainsbury’s - has said that it wants to help change the image of AD as a waste management add-on, and focus on producing energy from organic waste. This change is the key to the delivery of the UK’s renewable energy infrastructure. With a little vision, we could build our energy security and waste management infrastructure on the back of British farming.

Rosaline Hulse is communications and systems executive at The Anaerobic Digestion and Biogas Association (ADBA)

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