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Hungry to start processing local food waste

Oxfordshire County Council and its Waste Collection Authority (WCA) partners recognised the need to increase the amount of biodegradable waste being diverted from landfill.  However, the WCAs could not commence collections without a treatment solution in place.  Given the aim of all partners to increase recycling rates and diversion from landfill it made sense to work together.  In 2007 all six authorities came together, working through the Oxfordshire Waste Partnership, to procure a joint organic waste treatment solution for the entire county’s food waste.  By working together, the authorities aimed to achieve economies of scale that later in the procurement process proved advantageous in securing value for money.

By working together, the authorities aimed to achieve economies of scale that later in the procurement process proved advantageous

Only three years ago, when the procurement started, the opportunities presented by Anaerobic Digestion were not widely recognised as the logical solution for the diversion of organic wastes from landfill. This begs the question: “Why did Oxfordshire County Council become one of the first local authorities to procure Anaerobic Digestion as its principal food waste treatment solution?”

Oxfordshire County Council was delighted to receive seven credible tenders, however, despite clearly stating that four of the five collection authorities would be collecting source separated food waste, remarkably only Agrivert - the eventual winning bidder - offered Anaerobic Digestion as a solution.

The evaluation focussed on environmental and sustainability criteria, and Agrivert provided a low-carbon solution through a combination of site location and technology provision. Councillors were particularly excited at the prospect of creating renewable energy from food waste.

By using Anaerobic Digestion, the County Council does not have to treat green waste to Animal By-Product Regulation (ABPR) standards and incur the cost of doing so

The proposal also demonstrated value for money on a number of counts. Firstly, by using Anaerobic Digestion, the County Council does not have to treat green waste to Animal By-Product Regulation (ABPR) standards and incur the cost of doing so. Secondly, because we could aggregate the individual collection authority waste arisings and offer larger tonnage to bidders, it enabled bidders to achieve economy of scale, resulting in a lower gate fee to Oxfordshire County Council.

Now that two of the collection authorities within the Partnership have started separately collecting food waste, it is felt that the message about producing renewable energy strikes a resonance with our residents - resulting in increased participation and capture rates. Early indications show that both participation and capture rates fare very well compared to the trials conducted by WRAP elsewhere in the country.

By using Anaerobic Digestion, Agrivert provided a solution that enabled a wider range of kitchen wastes to be accepted, simplifying the message to residents and making it easier to understand and engage with the service.  Acceptable kitchen wastes include items such as bones, dairy products and oils.

Agrivert was also able to demonstrate how it was able to overcome contamination issues, thereby offering a more user-friendly service to the householder and offering reassurance to the Council of the robustness of the solution.

The County Council was impressed with Agrivert’s record in marketing digestate like products, critically providing benefit to the agricultural community.

Oxfordshire County Council’s Cabinet Member for Growth and Infrastructure Ian Hudspeth explains: “Local authorities are increasingly being called upon to find alternatives to landfill and will have to foot a considerable bill in the form of landfill tax if they fail to act over the next few years. In Oxfordshire we want to make sure we are well placed to meet these requirements and anaerobic digestion of food waste is an important part of that commitment. We are delighted to be able to provide the collection authorities with a local solution, meaning all organic waste is treated within Oxfordshire, while producing green electricity and providing quality fertiliser for local agriculture.

“The introduction of food waste collections across Oxfordshire with diversion through the Agrivert facilities will increase our recycling rate to more than 55% and divert an additional 40,000 tonnes of organic waste from landfill each year.”

The Anaerobic Digester is currently under construction and is due to open this August.  In the meantime all the waste collected is being treated within the county at Agrivert’s in-vessel composting facility at Ardley.

Oxfordshire County Council head of waste management Andrew Pau is proud of the county council’s pioneering approach: “I am very excited about the project with Agrivert because it will allow us to make a step change in our landfill diversion rates.  Although there is some merchant AD capacity in the UK, this is the first AD facility procured on this scale by a local authority. Oxfordshire is pleased to be leading the way with a technology that is only now recognised to be at the top of the hierarchy for the treatment of food waste.”

A significant amount of energy is anticipated to be generated, 15,000 MWh each year, not only reducing our reliance on fossil fuels but also enabling some subsidy of the gate fee. The AD solution now forms a very strong long term partnership between Oxfordshire County Council, the Oxfordshire Waste Partnership and Agrivert.

Rebecca Harwood is Waste Contracts Officer at Oxfordshire County Council

The processor’s perspective

Agrivert is delighted to be working in partnership with Oxfordshire to turn a problematic waste into a valuable commodity; one which will be used to generate renewable energy and provide a valuable organic agricultural fertiliser.  We have found that by focussing on reduced carbon solutions we can offer better value for money to our customers. Applied to Oxfordshire, this approach resulted in a waste solution that is local, diverts organic waste from landfill, and generates renewable energy - reducing our reliance on fossil fuels.

Agrivert believes that anaerobic digestion is an excellent solution for certain local authorities collecting source segregated food waste. However, its suitability depends on many factors:  local demographics, population density, current collection arrangements and waste volumes, for example. For one Oxfordshire district, commingled food and green collections were clearly the best collection option. To accommodate this, Agrivert’s solution for Oxfordshire provided both anaerobic digestion and In-Vessel Composting facilities. Both facilities have received welcome financial support from WRAP.

Waste facilities are extremely capital intensive, but tend to offer strong economies of scale. The greater the volume throughput, typically the lower the unit cost can be. So Agrivert tries to maximise the size of the plant design in the light of locally available wastes. 

Smaller scale solutions are possible, of course, and in some circumstances may represent good value. But authorities such as Oxfordshire, who have the ability to work together to aggregate waste to achieve higher volumes, are likely to benefit from much better value for money than those who procure against smaller waste volumes. 

Agrivert’s philosophy is to provide customers with a practical and reliable solution, which reduces carbon and offers outstanding value.  With Anaerobic Digestion, we selected a German partner whose technology has been tried and tested over many years with similar waste streams; and whose plants now generate over 100MW of renewable electricity each year. This technology has nonetheless had to be adapted to comply with local waste regulations, such as the Animal By-Products Regulations. 

The Oxfordshire anaerobic digestion plant has posed a number of interesting challenges over the past year. The most recent has been attempting to progress construction during the coldest winter for 30 years! But with the warmer - and occasionally drier - spring weather now with us, the site is rising from the ground very quickly.  With commissioning due to take place in July, Agrivert, and our joint venture partners M&M Skips, are looking forward to receiving our first waste through the doors at Yarnton in August 2010.

James Astor, Agrivert managing director

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