Wolfgang Bengel, the technical director at German biomass company BMP Biomasse Projekt, saw a business opportunity in solving the breweries' grain waste headache. He reasoned that the leftover grain could be used to create steam and biogas, which would provide energy for the breweries, cheapening their energy costs as well as their costs of transporting grain to farms.
Bengel has successfully treated the residue from rice and sugar cane in boilers with atmospheric fluidized bed combustion systems, to produce energy in China and Thailand, and Bengel thought a similar process could be developed for the breweries' spent wet grain. Water would first have to be removed from the wet spent grain, the grain would have to be dried and then burned to produce energy. "Beer making is energy intensive - you boil stuff, use hot water and steam and then use electric energy for cooling - so if you recover more than 50 percent of your own energy costs from the spent grain that's a big saving," says Bengel.
BMP turned to a long-standing business partner, fellow German biogas plant specialist INNOVAS, which had worked with it in China, to help develop the method as a EUREKA project. Germany's BISANZ, which works on engineering projects, was also enlisted, as was Slovakian partner Adato, which designs boilers. By chance, BISANZ had been working on a boiler plant for a waste management company which entered bankruptcy, with assets being sold. The partners decided to buy the unwanted plant and to adapt the equipment to the process of burning spent grain.
Researchers had to add extra cleaning and filtering equipment to the combustion equipment they had bought. There are extremely high European standards for combustion and the team had to extend the research timetable as its initial burning tests failed to meet the requirements. "We had more than 50-60 test periods of burning mixtures of spent grain," says Bengel.
They have managed to refine the process so that the burning met the requirements. They also perfected a process for the anaerobic treatment of the waste water from breweries, thereby producing a complete system for breweries to treat their complete waste stream, wet spent grain and waste water. One of Germany's environmental protection agencies (TÜV) certified the burning process as up to standard.
Breweries who sign up could become greener breweries, creating their own energy and cutting down on lorries travelling to and from their factories. "Out of 100,000 tonnes of wet spent grain, you have 2,000 tonnes or even less of ashes," says Bengel.