Sustainable Production of Biofuels from Domestic Lignocellulosic Wastes using Extremophiles

Research mentor: Dr. Rajesh K. Sani, Department of Chemical and Biological Engineering.

Biofuel process Picture

The long-term goal of the project is to develop an integrated sustainable biological process for cost-effective conversion of lignocellulosic wastes to usable power. In contrast to fossil fuels, hydrogen (H2) is renewable as it can be produced by biomass and can be converted into electrical energy in fuel cells, and is a clean energy carrier with a high energy-yield. Thus it is a promising alternative fuel of the future 23-25. In South Dakota, prairie cordgrass (PCG) is abundant, and can offer regional alternatives to corn for production of fuels. In our previous work, we selected and characterized several thermophilic microbes from core samples collected from the deep biosphere (4,850 feet deep) of the Homestake Gold Mine (Lead, SD) and Hot Springs (Thermopolis, WY) 26,27. One consortium of thermophiles is able to both, breakdown complex biomass, and then ferment the simple sugars resulting from the initial stage. This consortium (Figure 1) can grow on untreated lignocellulosic biomass (PCG) at 60°C and produces 28 ml H2/g PCG after three days.

SD-RET research project: One of the obstacles in converting lignocellulosic feedstocks to biofuels is the expensive physiochemical pretreatment (acid, alkali, hydrothermal, or ammonia), as well as enzyme cocktails to hydrolyze cellulose and hemicellulose into fermentable sugars 28. The inclusion of these steps reduces the overall cost-efficiency of the process. Lignocellulosic biomass is inexpensive ($2-4/GJ at a cost of $39-60/dry ton biomass) but its pretreatment cost ($15-25/GJ), along with the high cost of commercial lignocellulose-hydrolyzing enzymes, dramatically reduce the overall cost-efficiency of the process.

The SD-RET RAs will:

  • receive training in extremophiles, anaerobic microbiology, and microbial degradation kinetics,
  • convert lignocellulosic wastes into H2 using existing extremophiles, and
  • optimize various parameters including composition and concentration of wastes and microbial medium components for higher yields of H2.
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South Dakota School of Mines & Technology
Department of Mechanical Engineering