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. The on-site anaerobic digestion process was installed in 2015 and will be fully operational by May 2016.
Their Challenges
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. Working with Lake District Biogas, it is addressing these issues by removing inefficiencies in the disposal of its process residues and whey permeate.
Our Solution
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. Clearfleau is also responsible for the operation and maintenance of the upgraded bio-energy plant which will transform the creamery operation by:
• Generating 5.35 Megawatt hours (MWh) of renewable energy3 of biogas
• Treating 1,650m3 per day of process effluent and whey3 of biogas
• Producting around 1,000 Nm3/hour of biogas3 of biogas
• Revenue for energy generated from FITs and RHI3 of biogas
• Reducing costs by cutting fossil-based fuel purchase3 of biogas
Financing and Operation
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.
Once commissioned, the site will be operated by Clearfleau, providing renewable bio-energy for cheese making, reducing the environmental impact of the First Milk creamery and allowing cleansed water to be discharged to the nearly river.
Clearfleau had looked at another First Milk site prior to being asked to design a plant for the Aspatria site. 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.
How On-site AD Works
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.
Commercial Benefits
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.
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. The project is also boosting First Milk’s CSR credentials and contributing to energy supply in the community.
Gordon Archer – chairman of Lake District Biogas commented:
“Completion of this £10 million project on time, given the weather conditions in Cumbria this winter, has been a major achievement for Clearfleau. This is the largest AD plant on a dairy processing site in Europe dedicated to handling the liquid residues from the cheese making process.
Project Impact
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 (the largest plant we have built to date).
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. This plant is showcasing the potential for on-site energy generation in the European dairy sector.
Gordon Archer also commented “The on-site digestion facility will have a lasting impact on the commercial performance of the Aspatria creamery. 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.
