IDM | Technology/IT Lake District Biogas Green energy from Cumbrian cheese Clearfleau, leading British provider of on-site treatment solutions for the food and beverage sector, has commissioned its most complex plant to date, that feeds bio-methane into the gas grid in rural Cumbria. By feeding the bio-methane into the gas grid, the £10m facility will produce over £3m per annum in cost savings and revenue, while supplying up to 25% of a First Milk creamery’s energy requirements. The plant has been designed and built for Lake District Biogas, which will operate the site for twenty years taking feedstock from First Milk’s Aspatria creamery site. This comprises low-strength wash waters such as process rinses, supplemented by whey permeate (cheese production residue after protein extraction for use in energy supplements). This is pumped to the AD plant from the creamery. Gas from cheesemaking residues This is the first on-site Anaerobic Digestion (AD) plant in the dairy industry in Europe to feed bio-methane to the gas grid, generated exclusively by digesting cheese making residues from First Milk’s Lake District Creamery. At full capacity – from May 2016, the plant can treat 1,650m3 per day of process effluent and whey and generate around 5MW of thermal energy. The AD produces 1,000m3 of biogas per hour, of which over 80% will be upgraded for injection into the national grid. At least 60% of the bio-methane will be used in the creamery for steam generation, with the balance being used by local businesses and households in Aspatria. Revenue benefits include 20-year index-linked, governmentbacked incentive payments, with about £2 million per annum in support through the government’s RHI scheme and a further £1 million through the sale of gas to the wholesale market and from the Feed in Tariff scheme for the power generated in the CHP engine. The new plant, with its state of the art British technology, will take over from an outdated aerobic plant. This will have saved First Milk from having to upgrade the old inefficient plant, reducing their effluent treatment costs and carbon footprint, while cutting operational costs, which are borne by Lake District Biogas. Additional benefits from the deployment of on-site digestion in the dairy processing sector include reduced energy and off-site disposal costs. Upgrade for biogas The biogas is stored in a gas dome before being upgraded to biomethane – 80% of the biogas with at least 55% methane is fed to a membrane based upgrade unit that removes CO2 from the gas to produce bio-methane with a comparable thermal value to North Sea 24 · 9 2016 | international-dairy.com Clearfleau has commissioned the first anaerobic digestion plant to supply the UK gas grid with biogas generated only from cheese production residues (photo: Clearfleau) gas (some biogas is also fed to a CHP unit to provide power to run the treatment plant). As an initial step, Clearfleau refurbished the existing aerobic plant to enable First Milk to significantly reduce levels of phosphate in their effluent, which is discharged to the River Ellen. Supported by the Environment Agency, this will ensure an early delivery of new tighter discharge standards, which are required by the Water Framework Directive. Clearfleau’s on-site AD technology is proven to reduce the chemical oxygen demand (COD) of the production residues by at least 95%. Aerobic polishing will then remove residual COD and nutrients (nitrates and phosphates) to allow safe river discharge. Downstream treatment will take place in an existing aerobic plant which Clearfleau has upgraded and enhanced through provision of chemical treatment for nutrient removal. The residual sludge from the plant will be spread on local farmland as a nutrient rich soil improver. On-site digestion will produce over £2m per annum in net revenue (after operating costs) from savings, incentives and gas sales.
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