Spent grain
The main brewery waste is spent grain. Other process wastes are stale beer and yeast residues.
It can be and should be processed into biogas. Additionally, expired beer and yeast residues can be processed. There are two alternative ways to process beer spent grains: drygrains or biogas.
Dryer or biogas plant?
It was considered that drying spent grain is cheaper and better than a biogas plant. However, dry feed competes with fresh grain. When there is grain overproduction on the agricultural market, grain has a low price. And dry feed is difficult to sell, and drying is unprofitable. Drying is just a way to get rid of waste.
Spent grain recycling into biogas is possible both as a replacement for natural gas in brewery boilers and as well as for power generation.
Spent grain consists of 25% solids. Therefore, it can be processed using high-load reactor technology (HLR). With the direct replacement of natural gas by biogas in boilers, the capital costs for a biogas plant are lower because there is no need to buy a generator.
Taken together, these two factors (high-load reactors and generator savings) lead to investment in a biogas plant can be compared to an investment in drying.
A biogas plant is ultimately a more economical option than spent grain drying. The payback time for such a biogas project is 2-3 years. Unlike drying, biogas plants don’t consume but rather produce energy.
NGE Biogas has built biogas plants for a wide variety of substrates: distillery wastewater, carrot pulp, sugar beet pulp, corn silage. These types of raw materials are similar to spent grains.
That is why NGE Biogas is able to build a biogas plant on spent grain.