The Brewing Process
This is a simplified look at the traditional brewing process. Malt, consisting primarily of barley and other grains, is added to the mash tun and filled with water. This is then heated to a point where the sugars from the grains are separated and dissolved into the water. This water is then moved to another tank where it is fermented with hops and yeast. After fermenting, it is filtered into the beer form we recognize and love.
After the grains are utilized for their sugars in the mash tun, they are disposed of as what is refered to as spent grain. These grains are high in protein, fiber, and fat, but the nutritional value is hard to capture due to the high water content and quick spoilage. Below is some more information showing the issues surrounding this valuable by-product.
Spent Grain Statistics
Spent Grain Problems
Spent grain spoils very quickly. When a brewery smells sour, or funky, this means there is spoiling spent grain that has yet to be disposed of on the premises. If it is kept on site for more than a day or two, this smell becomes very potent.
Spent grain contains over 80 percent water. This means that when these grains are transported, over 80 percent of the costs and emissions from this are due to the water content, only 20 percent for the actual grains.
Current disposal methods all involve either transporting water-heavy, time-sensitive grains significant distances, or creating expensive, small-scale alternatives. These options consist of:
Giving it to a farmer for animal feed, relying on prompt collection and transport. This can prove especially difficult for urban breweries.
Anaerobic Digestion. This can create bio-fuel, but is very capital intensive and cannot process a large and consistent output of spent grain.
Landfill. This is the worst possible option due to the transportation costs associated and the methane and CO2 released into the atmosphere during decomposition.