Sweet sorghum is a hardy crop that can be grown on marginal land and can provide both
food and energy in an integrated food and energy system. Lignocellulose rich sweet sorghum
bagasse (solid left over after starch and juice extraction) can be converted to bioethanol
using a variety of technologies. The largest barrier to commercial production of
fuel ethanol from lignocellulosic material remains the high processing costs associated
with enzymatic hydrolysis and the use of acids and bases in the pretreatment step. In this
paper, sweet sorghum bagasse was pretreated and hydrolysed in a single step using microwave
irradiation. A total sugar yield of 820 g kg1 was obtained in a 50 g kg1 sulphuric
acid solution in water, with a power input of 43.2 kJ g1 of dry biomass (i.e. 20 min at 180W
power setting). An ethanol yield based on total sugar of 480 g kg1 was obtained after 24 h
of fermentation using a mixed culture of organisms. These results show the potential for
producing as much as 0.252 m3 tonne1 or 33 m3 ha1 ethanol using only the lignocellulose
part of the stalks, which is high enough to make the process economically attractive.