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Six-fold increase in anaerobic digestion possible in Scotland

Zero Waste Scotland has today published research suggesting that 1.35 million tonnes of food waste could be transformed into new products through the increased use of anaerobic digestion (AD) technology available in Scotland.

22 Mar 11

The report Digestate Market Development in Scotland suggests a six-fold increase in the use of AD facilities is possible in Scotland if the country is to make the most effective use of its food waste.

AD is a well proven renewable energy and waste management technology which produces renewable energy in the form of biogas and digestate from organic materials.

At present there are six AD sites in operation or in construction, with a combined capacity of 207,500 tonnes.

Processing available food waste in this way could produce 1.1 million tonnes of digestate which can be used as a fertiliser product.  Digestate has a potential market value of around £5/tonne; this suggests a £5.5 million market for digestate.  Current inorganic fertiliser (NPK) blends can sell for up to £300/tonne so digestate could offer a competitive alternative for farmers.

The report also concludes that whilst agriculture is the key market for digestate, brownfield regeneration sites are also an attractive market for those facilities located near urban locations, such as the Polkemmet-Heartlands Project near Whitburn. The project will transform a derelict coal mine into two championships golf courses, hotel and leisure facilities and 2,000 new homes using manufactured topsoil made from BSI PAS 100 compost and crushed colliery spoil. Digestate trials are currently take place on site.

However, the report also identifies a number of barriers which need to be addressed to increase digestate’s marketability. In particular, the current market price limits the radius within which digestate can be transported cost-effectively.  The report suggests that at £5/tonne this distance is currently limited to 10-12 miles. If the price of digestate increases, this distance will also increase.

The report also recommends focussing on PAS110 accreditation for sites, the industry specification against which producers can verify that their products are of consistent quality and fit for purpose, to comply with new regulations in the Scottish Government’s Zero Waste Plan, and also to maximise the market potential for digestate.

Louise McGregor, Head of Market Development for Zero Waste Scotland said:

“This report highlights there are both barriers and opportunities for maximising the use of digestate in Scotland.  Whilst there are still significant challenges in accessing food waste feedstocks, the drive to get food waste out of landfill is a big opportunity to make AD much more prevalent across Scotland, but there needs to be a focus on ensuring high quality outputs from these facilities to create robust markets for digestate.  This will be a major focus of Zero Waste Scotland’s new Business Plan.”

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