Introduction Site and Surroundings
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Ashford Borough Council - Report of Development Control Managers Planning Committee 19 October 2011 ___________________________________________________________________ Application Number 10/01491/AS Location Land West of Thimble Hall between CTRL and M20, Leacon Lane Charing Grid Reference 95006/47458 Parish Council Charing Ward Charing Application Renewable Energy unit facility which will comprise of plant Description and structures for the storage of material for production of biogas, together with ancillary structures and buildings Applicant Future Biogas Ltd Agent Golder Associates, 1 Alie Street London E1 8DE Site Area 3.9 Hectares (a) 54/28R (b) Charing R (c) KH X, EA X, KPROW X, SEW X, Little Chart R CPRE X, WKPS R, RPL X Westwell R Amends (a) 81/30R (b) Little Chart R, (c) KH X, KPROW X, EA X, HS1 X, petition 517 Westwell R EH (EPM) X, Charing Design signatories Egerton R, Group R Pluckley R Introduction 1. This application is reported to the Planning Committee because this is a major proposal. It was last reported to Committee on 9 March 2011 when Members deferred making a decision in order for Officers to obtain further information as requested by consultees and in particular to obtain further evidence of the proposed traffic generation and the impact of that traffic on the road network of the proposed catchment area of the plant. Site and Surroundings 2. The site lies approximately 1 km west of Westwell Leacon and 1.5 km south of Charing. It is bounded to the north by the Channel Tunnel Rail Link which lies on an embankment and to the south by Leacon Lane and a woodland strip which screens the M20 motorway, which lies to the south of the lane. On 2.1 Ashford Borough Council - Report of Development Control Managers Planning Committee 19 October 2011 ___________________________________________________________________ the eastern boundary is a tributary of the River Great Stour. Access to this site is from Leacon Lane which runs from A20 at Westwell Leacon exiting at The Pincushion on the Pluckley Road just north of the M20 motorway. 3. The site which is grade 3 agricultural land, is at present under cultivation. The nearest residential property is approximately 220 m to the east, this being Thimble Hall, a Grade II listed building. This lies on higher land than the application site. 4. The application site itself slopes from the north west towards a low point in the south-west corner and there is a difference in levels across the site of approximately 10 m. 5. Close to the site is an underground electricity cable and connection to the National Grid is possible. 6. The site lies in the open countryside forming the Charing Heath Farm landscape character area. The land owner of the site is a local farmer. A location plan is attached as appendix 1. Proposal Process Original Scheme 7. Originally the application was for full planning permission for a renewable energy facility of 2MW capacity that uses silage feedstock to produce biogas that will be used to generate electricity to be exported to the national grid. 8. The proposed facility will convert up to 43,000 tonnes per annum (tpa) of locally sourced maize, grass silage and sugar beet energy crops into biogas using a closed loop process. The biogas will be collected and used as fuel to produce renewable energy. In addition to the production of renewable energy, approximately 30,000 tpa bio fertiliser will be produced from the digestion process. This bio fertiliser (or digestate) will be returned to the land and used as fertiliser and soil improver by local farmers for the following year’s energy crop. The bio fertiliser would have the potential to remove the need for existing industrial fertilisers to be delivered to the farms and distributed on the land. The facility will only receive energy crops grown and sourced locally for the purpose of biogas. 9. The process will be fully automated by computer-controlled systems to maintain optimum energy production and efficiency. Biogas production is a continuous process but relies on the seasonal production of energy crops which are stored in the silage clamps. These clamps have sufficient capacity 2.2 Ashford Borough Council - Report of Development Control Managers Planning Committee 19 October 2011 ___________________________________________________________________ to supply feedstock for the unit’s year - round operation. A series of sealed liners will cover the feedstock materials stored in the clamp to eliminate odour and particulate emissions during storage and prevent deterioration that may affect the quality of the feedstock during storage. Surface water run-off will be passed through a drainage system while the leachate produced from the clamp will be drained and collected separately and will be fed to the biogas digester. 10. The silage will be stored in the clamp until required and then loaded into the feed hopper. Once in the digester, the feedstock will be stirred with large paddles to allow the digester to operate. The digestive process is anaerobic; i.e. it operates in the absence of air, so the digester will be sealed to eliminate air from the process. Naturally occurring micro organisms within the feedstock are activated in the digester to break down the feedstock material into methane gas and a compost like digestate. The digestate (or bio fertiliser) is continually removed from the process and stored on-site in a tank until it is taken to be spread on agricultural land as a fertiliser for the following year’s energy crops. 11. The methane from the digester is collected and stored in a gas holder. A regulated flow of methane is fed to the biogas engine to produce renewable electricity which will be fed to the national grid by an underground service trench and duct to the substation at Little Chart. The plant is expected to produce in excess of 16,000MWh of electricity per year. This is sufficient for over 4,500 houses, i.e. it would export enough electricity to supply the villages of Westwell Leacon, Hothfield, Little Chart and Charing. Total CO² emissions avoided (based on the UK average 0.6 2 kg CO² per k Wh conventional electricity) are estimated by the applicants to be 9,900 tonnes per annum. Amended Scheme 12. The scheme now has been reduced in size with an operating capacity of 1.5 MW; this is because there is a capacity limit of the grid connection at Little Chart. The proposed facility now has the capacity to process up to 25,000 tonnes of input biomass per annum. This would produce 12,000 MWh per year of renewable electricity and provide electricity for the equivalent of 3,375 homes saving 7,425 tonnes of CO² per annum. It is proposed to accommodate 5,000 tonnes of silage on site in just one clamp with the remaining 20,000 tonnes stored at the farms which are producing the crops within 10 mile radius of the plant. This silage will be transported to the biogas site when required. The resulting output fertiliser will be in the order of 18,000 tonnes- down from 30,000. It is expected that 4,000 tonnes of liquid biofertiliser will be piped and irrigated using the existing irrigation system by the host farm. It is predicted that this will in effect reduce the original transportation requirement by over 47%. 2.3 Ashford Borough Council - Report of Development Control Managers Planning Committee 19 October 2011 ___________________________________________________________________ Development on site 13. The following buildings are now proposed: • Main Fermenter 23m in diameter 8.5m high (3,300m³ capacity) • Storage Tank 36m diameter 6m high, with a conical roof up to 14m • Gas Engine Container 12.5 x 3.2 x 3.2 (L x W x H) with an exhaust stack of 12m together with a smaller auxiliary flare • Silage Clamps – originally 3 were proposed 60 x 24.5 x 3.5 (L x W x H), now 1 is proposed 90 x 24.5 x 3.5 • Control Building 12.8 x 6 x 2.97 m (L x W x H) • Office/Shed 12 x 4 x 3.2 m (L x W x H) 14. All silage liquids will be captured in a 30m³ underground tank at the lowest point of the clamp and used in the process as a feedstock to generate biogas. Figure 1: Proposed Layout and Site Sections 2.4 Ashford Borough Council - Report of Development Control Managers Planning Committee 19 October 2011 ___________________________________________________________________ Layout 15. The main fermenter, storage tank, controls building and gas engine container, including exhaust stack, would be located close to the southern site boundary, the lowest part of the site. Since the original submission the plant has moved slightly further away from the southern boundary, and at its closest point it is now 10m from the road. The 12 m high stack would sit on the 68 m contour, making the top of the stack approximately 80 m Above Ordnance Datum (AOD) compared with the level of the CTRL railway line that runs between 76.28 and 76.88 m AOD. The tallest structure on the site, the storage tank, would sit between the 68 and 69 m contour and the tip of the conical roof would be approximately 82.5 m AOD however the vast majority of the building will be significantly below the level of the CTRL line. 16. The silage clamp will be located between the storage tanks and the railway line on the northern side of the site. The total developable footprint (i.e. the areas of hardstanding and structures) is approximately 0.98 ha of the 4.5 ha site.