Techno-economic feasibility of using sorghum brewers spent grain to generate one megawatt of electricity using direct combustion technology

Abstract

The paper presents a study that was conducted to assess the techno-economic feasibility of a sorghum brewers spent grain (BSG) fired boiler unit to generate 1 megawatt of electricity for a certain brewery company. The brewery company is currently generating 24 tons per day of sorghum brewers spent grain biomass waste which was used as a source of boiler fuel for this work. After a full proximate analysis the sorghum brewers spent grain had an average heating value of 12.6 MJ/kg whilst coal had 19.9 MJ/kg indicating that it is feasible to generate electricity using sorghum brewers spent grain as a source of fuel, and that sorghum brewers spent grains can be used as an alternative to coal. A process for conversion of the BSG to electricity was proposed for a biomass boiler unit consuming 1100 kg/hr BSG, operating at 86% efficiency, maximum pressure of 9 bar and steam output of 1689kg/hr was designed to supply a one megawatt turbine generator. Pressure, temperature and flow control mechanisms were assessed as a safety consideration. An economic analysis was done with a total investment cost of USD$ 3.4 million, a payback period of 3.7 years, and a return on investment of 27.4%. BSG provide an alternative source of electricity for the brewery industry