Yet another surprising source of ‘green’ energy came to our attention recently; apparently food waste is a useful source of biogas, and biogas can be used as a direct replacement for the usual household gas derived from fossil fuels, but at a much lower cost to the environment. The production of biogas is on the point of being expanded in the Lake District, where a new government-supported green energy plant will be coming into operation. This plant will be using the waste products from cheese manufacture as a source of the gas, and this gas will either be used by the creamery itself as a source of energy, or fed into the grid to provide energy for local residents.
The Lake District Creamery is based in rural Aspatria, Allerdale in Cumbria, and is a major manufacturer of premium cheddar cheese. The by-products of the cheese manufacturing process consist of whey (a watery liquid) and other milk residues, and these are to be fed into a new anaerobic digestion plant which has been built nearby. The digestion process will produce the equivalent of the annual gas requirements for 4,000 homes. Of the gas produced, roughly 60% will be used within the creamery to generate electricity (thereby cutting energy costs), and around 1,600 home’s worth will be made available to local businesses and residents for both cooking and heating.
Industry-Wide problem of waste disposal
It’s a neat solution to a problem that is industry-wide – how to dispose of the watery whey and the other milk residues economically and without harming the environment. Basically, all the organic residues and liquids produced during cheese manufacture are collected in giant tanks, and bacteria are allowed to grow and ‘digest’ the sugars in the contents. This digestion process produces a number of gases, including methane, which would otherwise be released into the environment if the residues were simply dumped. The gas mixture (1,000 cubic metres will be produced every hour) can then either be used in the plant for electricity generation, or be further processed to remove any carbon dioxide, which leaves a purer ‘biogas’. The biogas can then be made available to homes and businesses as a substitute for fossil fuel generated North Sea gas.
This new source of energy has only been made possible via government subsidies of £2M a year, and these subsidies are recovered from consumers in their energy bills over a number of years. However, the new biogas plant is a step towards our achievement both of the EU renewable energy targets and also our own drive towards achieving climate change goals. The people using the biogas will be blissfully unaware that it has been made from cheese – it will be supplied through the gas mains just like North Sea gas.