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An Appealing Solution: Recovering Energy and Water from Potato Skins

Cambridge Eco visits Branston’s brand new anaerobic digestion facility 


Branston Ltd recently unveiled their new anaerobic digestion (AD) plant in Lincolnshire, UK. The key benefits of this sustainable project are the creation of energy from waste and optimal water recycling during their potato processing operations.


Dr Mary Dimambro and Dr Joachim Steiner from Cambridge Eco Ltd met David Nelson, Field Director and Vidyanath Gururajan, Projects Director at Branston, at the new AD plant. The main feedstocks for the digester are currently outgrade potatoes which are unfit for consumption and waste from Branstons’ brand new £3.5 million prepared food factory. The feedstock is expected to contain an increasing percentage of potato peelings as new parts of the peeling plant will go into operation. The investment is the latest in several projects undertaken as part of Branston’s environmental strategy, which has led the company to become the first UK food producer to receive the Carbon Trust Standard and ISO 14001 accreditation.

”The AD plant was built by the UK's leading AD operators BiogenGreenfinch and produces 300kW of electricity” said Vidyanath Gururajan. “The green electricity is complemented by the introduction of a new water recycling plant, which will recycle some 60% of the water used to wash potatoes.”


David Nelson explained that “the AD plant has enabled Branston to become one of the first food producers in the UK to harness such innovative and environmentally friendly technology.  As well as being incredibly efficient, the anaerobic digestion plant is also safe, quiet and odourless. The combined heat and power plant is complemented by the water recycling plant which will considerably reduce our mains water consumption and ensure we maximise efficiencies throughout our two factories on site.”

The digestate produced at Branston’s AD plant is currently recycled to land by a local farmer. Dr Mary Dimambro, Managing Director of Cambridge Eco Ltd said: “The most common use for both composts and digestates produced from organic wastes in the UK is as a soil conditioner for agriculture. There is great potential to turn digestates that are currently classed as waste into a tested and certified marketable product. Cambridge Eco can assist in this process by carrying out field and glasshouse trials to find the optimum use for each individual digestate. Branston is in the process of obtaining PAS 110 certification for the digestate, which is an excellent first step towards marketing their digestate.”



Cambridge Eco visits German Biogas Plant


Bioferm Biogas Plant



Cambridge Eco visited one of the 27 dry fermentation biogas plants installed by BIOFerm GmbH in Germany. The plant produces on average 660kW of electricity using eight fermenting units. Surplus heat from the combined heat and power generators is used to heat commercial glasshouses nearby. The plant is owned and managed by a cooperative of six local farmers who also supply the biomaterials and use the resultant digestate on their land.


The BIOFerm system works by fermentation of dry organic materials (30%-60% dry content), such as grass silage and maize. The system at Kulmbach has eight fermenters, with a new batch being started twice a week.

Firstly, the feedstock is mixed with a quantity of already fermented digestate. The material is then placed in a 30m long and 5m high fermenter simply using a tractor with a front loader, then sealed to exclude oxygen and left there for 28 days. The bacteria mix needed for the fermentation is sprinkled over the biomass through pipes in the ceiling of the units. The biogas is extracted, condensed and stored above the fermentation units until it is burned in the CHPs.


Farmer, Mary Dimambro and Gernot Buchta

After the fermentation process, the digestate is partly reused to start the next batch in the fermentation units, and the rest is used by local farmers as high-quality fertiliser. The digestate can also be composted for use in the horticultural sector.

For more information about BIOFerm please visit their website:

The Gas Bag



Top right: The dry biogas plant in Neuenmarkt, Kulmbach

Middle right: from left: Alexander Hollweg, co-owner of the biogas plant, Mary Dimambro, Managing Director of Cambridge Eco Ltd, Gernot Buchta, Marketing Director BIOFerm

Bottom right: Gernot Buchta and Mary Dimambro next to the biogas storage bag

Article: Cambridge Eco Ltd visits BIOFerm, Neuenmarkt, Kulmbach. 6th May 2009