Prospective utilization of brewers' spent grains (BSG) for energy and food in Africa and its global warming potential

Low agricultural productivity and electricity shortages continue to plague Africa. Brewer?s spent grain (BSG) as a food source and precursor for biochar production via hydrothermal carbonization (HTC) can offer solutions. HTC involves the artificial coalification of biomass by direct injection of steam in a pressurized vessel to produce an upgraded biofuel with characteristics similar to coal. Demand for food security and energy are likely to lead to competing interests and uses of BSG. Therein lies the fundamental dilemma that constitutes the central issue here, which of the two options food or biofuel production from BSG will have the least impact on the environment? From a stochastic model supported by 50,0 0 0 Monte Carlo simulations BSG generation, biochar yield and energy potential for Africa were estimated up to the year 2040. This was coupled with model to assess the Global Warming Potential (GWP) of BSG treatment. Apart from a regional evaluation, detailed information at the country level was provided. Total BSG generation is estimated at 698,0 0 0 Mg (At a 90% confidence level roughly 0.52 - 0.91 million Mg/yr) for 2020 in Africa. By 2040 it is expected to rise to 852,0 0 0 Mg/yr (0.57 - 1.19 million Mg/yr at a 90% confidence level). Flour production can be expected to have a lower GWP compared to biochar production. The GWP of BSG conversion to biochar is more than 1,400 million CO2eq for a 20-year time horizon which is 3. 90 times higher than the alternative, BSG milling to flour for one case study. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

Automated summary

Low agricultural productivity and electricity shortages continue to be issues in Africa. Using brewer's spent grain (BSG) for food and biochar production through hydrothermal carbonization (HTC) could provide solutions. As BSG production and energy potential are expected to rise in Africa, the Global Warming Potential (GWP) of biochar production may be higher compared to flour production.