Coproduction of ethanol and power from switchgrass

Abstract

Three process designs for producing ethanol and electricity from switchgrass are evaluated: a basecase technology scenario involving dilute acid pre-treatment and simultaneous saccharifi cation and fermentation, and two mature technology scenarios incorporating ammonia fi ber expansion pre-treatment and consolidated bioprocessing -one with conventional Rankine power coproduction, and one coproducing power via a gas turbine combined cycle. Material and energy balances -resulting from detailed Aspen Plus models -are reported and used to estimate processing costs and perform discounted cash fl ow analysis to assess plant profi tability. The mature technology -designs signifi cantly improve both process effi ciency and cost relative to base-case cellulosic ethanol technology, with the resulting fossil fuel displacement being decidedly positive and production costs competitive with gasoline, even at relatively low prices.

Energy optimization of bioethanol production via hydrolysis of switchgrass

“…-The uncertainty in the operating conditions and the yield of the pretreatments [11][12][13]18,62,63 may change the decision upon the best process. It is expected that further experimental results will allow higher yields for the pretreatments consuming less energy, ammonia and freshwater.…”

Next-generation cellulosic ethanol technologies and their contribution to a sustainable Africa

“…Integration of second-generation biofuels production with dedicated electricity production from coal, natural gas or biomass can provide benefits in economies of scale (financial) and process efficiency. Both the biological (hydrolysis-fermentation) and thermochemical (gasification -synthesis) processes require the use of advanced, high-efficiency equipment for electricity production, to satisfy process requirements and provide surplus electricity for sale [89,90]. However, advanced equipment such as BIG/ CC systems [84,91,92] have high capital costs per unit electricity [19,93].…”

“…Economies of scale achieved through integration of electricity production in second-generation biofuel processes with electricity production in adjacent industrial facilities can reduce capital investment per unit of electricity substantially [24,90,92,94 -96]. Integration and scale-up of electricity and steam production can be achieved by combining feedstocks for electricity generation, such as lignin-rich residues from biological processing or residual syngas from gasification synthesis, and using heat recovery/integration in both biofuel and electricity generation for steam production and drying/evaporation [90,94,95]. The resulting maximization of electricity production will increase revenue to second-generation biofuels production, since it minimizes domestic/industrial heat production, for which limited markets are available [97].…”

Developing Organisms for Consolidated Bioprocessing of Biomass to Ethanol

“…Optimum use of cellulosic feedstocks can be achieved by integrating cellulosic ethanol processes with electricity production to achieve economies of scale and reduce capital investment per unit of electricity substantially (Easterly 2002;Hahn-Hägerdal et al, 2006;Laser et al, 2009a;Laser et al, 2009b;Sassner et al, 2008;Sims et al, 2008). Integration and scale-up of electricity and steam production can be achieved by combining feedstocks for electricity generation, such as lignin-rich residues from biological processing and using heat recovery/integration in both biofuel and electricity generation for steam production and distillation (Easterly 2002;Laser et al, 2009b;Sassner et al, 2008).…”