Green Gas Oxon Greening Oxfordshire's Gas
The following is some information about the project that we hope will explain the 'who, how and why':
Background to the Project
The architect of the project in 2013 was David Bermingham, a local Goring resident, who worked with Scotia Gas Networks to try to identify a suitable site for a plant which could produce green gas for the local area. The gas main which serves Goring and the local villages, and which would be capable of accepting biomethane, runs broadly along Icknield Road from the junction with the A4074 near Ipsden, down to Goring, where it crosses under the river and heads towards Yattendon and then onwards South to Brimpton. This gas main is the only one that runs at a pressure appropriate for biomethane injection, and so if the local villages were to be supplied with green gas, it would have to be via this particular gas pipeline.
Guy Hildred, a local farmer, owns the site of the plant (indeed he lives right next door to it), and is a big supporter of gas to grid anaerobic digestion. David and Guy worked together to assess the feasibility of the project, before making a planning submission to South Oxfordshire District Council, which was unanimously approved at a meeting of the council in January 2014. Construction commenced in May 2014, and the plant injected its first gas into the local grid in December 2014.
Both David and Guy, as local residents, are extremely aware of the sensitivity of the location within the Chilterns Area of Outstanding Natural Beauty. The selection of the site and the design of the project were both done with a view to minimising any adverse impact on the local environment, whether visual or otherwise. This included 'burying' the digesters 4m deep into the ground, to minimise their visibility.
Overview of the Plant
The AD plant at Icknield Farm consists primarily of two digester tanks (each 28m in diameter), two gas storage bags for the residue digestate, a small CHP engine (sitting within a container), and the gas clean-up equipment, which consists of two containerised membrane filtration units, a control house, and a network entry facility (the valves to enable the biomethane to be introduced into the gas main). There are three standard silage clamps (as seen in all dairy farms) to contain the maize and rye silage after harvest and pending introduction to the digesters (see below under Feedstock). See our gallery of pictures for greater detail.
Location
The site location is about as good as it is possible to find, being extremely close to the intermediate pressure gas main that serves the local community, with good transport connections, in an area that is very sparsely populated, and hardly overlooked. The topography of the site (it sits within a natural bowl) makes it extremely difficult to see from most aspects, and its location between existing farm buildings and a relatively large commercial site means that it does not create any form of a blot on the landscape, but blends in rather easily with its surroundings.
Feedstock
The plant consumes approximately 28,000 tonnes of mixed feedstocks annually, which are all locally sourced, and include maize and rye silage, together with some cereals, allowing the feedstock provider (Guy Hildred) to dispose easily of lower grade crop into the digester if he so desires, which might otherwise be expensive to treat before sale, or indeed might even otherwise be ploughed back into the ground.
Importantly, the plant will never use any food, garden, domestic or industrial waste. Its feedstock is exclusively farm products (crop and slurry). Using any other form of feedstock would require a much more complicated process, including pasteurisation and pre-sorting, and would require all kinds of environmental licences and an entirely different planning process through Oxfordshire County Council.
Energy Production
At current capacity the plant produces approximately 6 million cubic metres of biomethane per annum, or enough for the annual gas consumption of up to 5300 homes. A small amount of the raw biogas is used to run a combined heat and power engine which supplies electricity and heat for the needs of the plant itself. The biomethane is injected into the gas main at a point immediately adjacent to the site, and transported directly to local homes and businesses.