Draff is the damp grain that is leftover after the malting process when brewing beers and spirits such as gin and whisky. It is composed of grains including barley, rye, and wheat, depending on the alcohol it was used to produce. There may also be some other plant material present that is leftover from the brewing process, such as botanicals like juniper berries if the draff is a by-product of gin production.
On its own, draff is considered to be a low value waste product and is often given away to farmers to use as animal feed, but it can also be used as biofuel and has been used to create an innovative furniture material by a furniture designer in Dundee.
Location and Sources
Draff is a by-product of the brewing industry, and can be found wherever there are breweries and distilleries. Scotland has a thriving brewery and distilling industry and draff can be found across the country – from rural whisky distilleries in the Highland and Islands, to small craft beer breweries in the hearts of our cities. There are 115 breweries, 128 whisky distilleries, and 60 gin distilleries across Scotland.
Draff is predominantly composed of barley, rye, and wheat – and much of the grain used to produce beers and spirits will have been grown in Scotland. In 2020, an estimated 301,500 hectares of barley (65% of total crop production) and 93,500 hectares of wheat (25% of total crop production) were grown in Scotland. In 2019, 53% of barley grown in Scotland and around 33% of wheat grown in Scotland was sold for malting.
Application and product output
Currently the most common use for draff is animal feed – it is commonly given away to local farmers in its wet state by small breweries. Larger breweries and distilleries may dry it and sell it as animal feed, although the value is low (approximately £45 per tonne). If the draff isn’t dried then it must be used as feed quickly before it spoils, although the life is extended when the draff is dried and properly stored.
Draff, and other brewery and distillery by-products, can also be used to produce biofuel and chemical products.
Celtic Renewables are a Scottish company who use the ABE fermentation process to produce butanol, ethanol, and acetone from draff and pot ale (another distillery by-product). They are in the process of constructing their first large scale processing plant in Grangemouth, a town which has played a significant role in the production of chemicals and fuel from fossil fuels over the last century. Their plant will be the first bio-chemical refinery in the area and will use draff and pot ale from local distilleries to produce high value, sustainable chemical products as well as a high protein animal feed.
Another company exploring innovative uses for draff is Draff Studio – a furniture studio based in Dundee established by designer Aymeric Renoud. They use draff collected from local craft breweries and gin distilleries to produce a sheet material they call Draff Material. The wet draff is collected straight after the mashing or distilling process, often still with additional botanicals used in the distillation process intact. It is then dried out, and heat and high pressure are applied to create a sheet material that has a similar density to OSB (Oriented Strand Board – a sheet material composed of wood fibres oriented in opposing directions). This can then be used to create furniture products, and as a decorative cladding material. The draff used remains visible in the end material, and the end result varies depending on the grain or botanicals used in the source material.
A 2015 sector study by Zero Waste Scotland on circular economy in the whisky, beer, and fish industries also suggests that draff from the beer and whisky industry could be used in paper manufacture, and be included in bricks to increase porosity.
Production and sustainable consumption
Scotland is estimated to produce around 528,000 tonnes of whisky draff and 48,700 tonnes of beer draff annually. It is a by-product of alcohol production rather than a material in its own right, and is largely considered to be a low value waste product. Finding uses for draff once the grains have been spent during the production of beers and spirits has the potential to be a very sustainable material and helps avoid it ending up in landfill.
The current use of draff as an animal feed can be utilised to help to create a closed loop of nutrient recycling in the whisky and beer industries as manure produced by cattle fed draff can be spread on farmland where crops such as barley and wheat are grown as a fertiliser and soil-builder. Draff contains significant concentrations of nitrogen and phosphate, two of the most important nutrients when growing crops, and these valuable materials can be recycled back into the land via manure. These crops can then be used to produce more whisky and beer.
There is also a lot of scope for draff to play an important role as a material through some of the developing uses in Scotland. On an industrial scale, companies like Celtic Renewables are providing sustainable and low carbon alternatives to using fossil fuels, while small scale producers like Draff Studio play a valuable role in recycling draff from small craft breweries and distilleries in cities who may struggle to dispose of their draff in other ways.
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Renoud, Aymeric. “Material”. Draff Studio, https://draff.co.uk/material/. Accessed 17th February 2021.
“2. Distillery By-Products Output”. Distillery by-products, livestock feed and bio-energy use: report, Scottish Government, 2019. https://www.gov.scot/publications/distillery-products-livestock-feed-bio-energy-use-scotland/pages/4/. Accessed 17th February 2021.
O’Connor, Alison. “Brewing and Distilling in Scotland – Economic Facts and Figures”. Brewing and Distilling in Scotland – Economic Facts and Figures, Scottish Parliament, 2018.
“Cereal and Oilseed Rape Harvest: Final Estimates – 2020”. Scottish Government, https://www.gov.scot/publications/cereal-oilseed-rape-harvest-2020-final-estimates/pages/11/. Accessed 17th February 2021.
“Circular Economy: Sector Study on Beer, Whisky and Fish”. Zero Waste Scotland, https://zerowastescotland.org.uk/sites/default/files/ZWS645%20Beer%20Whisky%20Fish%20Report_0.pdf. Accessed 17th February 2021.
“Celtic Renewables”. Celtic Renewables, https://www.celtic-renewables.com. Accessed 17th February 2021.