LAKE DISTRICT BIOGAS - GREEN GAS FROM CHEESE RESIDUES
First Milk creamery produces bio-methane for the nearby gas grid
First Milk’s Aspatria creamery produces award winning cheddar cheese under the Lake District brand. The creamery, located in rural Cumbria, is Europe’s first dairy processing site to feed bio-methane (up-graded biogas) generated entirely from cheese process residues to the gas grid.
Like many dairy businesses, First Milk’s Lake District Creamery (one of the main cheese factories in the UK) was under pressure to reduce costs, cut fossil fuel energy use and limit its impact on the local environment. Due to pressure on milk prices affecting the entire European dairy industry, it also needed a funding partner for the project.
Early in 2015, Clearfleau undertook the initial upgrade of an existing aerobic treatment plant at the Aspatria site, prior to starting the new anaerobic digestion plant. The on-site facility will treat all the process residues from the cheese creamery and transform the creamery operation by:
Generating 5.35 Megawatt hours (MWh) of renewable energyTreating 1,650m3 per day of process effluent and wheyProducing around 1,000 Nm3/hour of biogasRevenue for energy generated from FITs and RHIReducing costs by cutting fossil-based fuel purchase
Lake District Biogas (www.lakedistrictbiogas.com) commissioned Clearfleau to design and build the new on-site AD plant. The upgraded treatment plant is a major boost for the creamery, plus local farms that supply the milk and the local community, who will have access to gas from the plant.
The site will be operated by Clearfleau, providing renewable bio-energy for cheese making, reducing the creamery’s environmental impact and allowing cleansed water to be discharged to the nearly river. Clearfleau also worked with the funding partners that formed Lake District biogas as a separate business to build, own and operate the proposed plant on behalf of First Milk.
The residues are pumped from the creamery to balance tanks before being fed into the digester tanks. Blending of high and lower strength feedstocks with high rate mixing and Clearfleau’s solids management system optimises biogas output. The large volume of whey permeate being fed to the plant produces over 1,000 m3/hour of biogas with a methane concentration of at least 55%.
Biogas is stored in the gas dome before upgrading to bio-methane (some gas is also fed to a CHP unit to provide power to run the entire plant). 80% of the gas is fed to a membrane based bio-methane upgrade unit that converts it into bio-methane with a comparable thermal value to North Sea gas.
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.
The new plant will provide significant treatment and disposal savings. By feeding the up-graded bio-methane into the gas grid, the facility will produce over £3m per annum in cost savings and revenue, while supplying up to 25% of the creamery’s energy requirements. On-site digestion will produce over £2m per annum in net revenue (after operating costs) from savings, incentives and gas sales.
Initial work in early 2015 addressed issues with the site’s existing aerobic treatment plant, before embarking on the digester project, a complex build involving site clearance and construction of two 5,000 m3 digester tanks. With biogas being upgraded into bio-methane, First Milk will be using energy from their process residues to run the factory, cutting costs and carbon emissions.
The on-site AD process converts over 95% of the biodegradable material into biogas. Each cubic metre of liquid feedstock fed into the AD plant generates about 14 cubic meters of gas. The plant generates 1,000 cubic meters per hour of biogas or 16,000 cubic meters per day of bio-methane.
The creamery will have a state of the art facility to handle its residues, reducing costs and carbon emissions. With funding from outside the business and by outsourcing the plant’s operation and maintenance to Clearfleau, First Milk can focus on its core cheese production activity. This plant is also showcasing the potential for on-site energy generation in the European dairy sector.