Design and evaluation of biomass utilization systems
Massachusetts Institute of Technology. Department of Mechanical Engineering.
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This thesis designs and evaluates systems to utilize two problematic biomass sources, hurricane debris and invasive water hyacinth, and turn costly cleanup efforts into opportunities for biofuel conversion systems. A novel solution is proposed for each biomass source and techno-economic models accounting for economic, energy, and carbon costs are used to evaluate different options for utilization. Hurricane debris is a feedstock that gets generated in vast quantities in an unpredictable manner, thus its main challenge is its supply chain. We propose a 30MW barge-mounted biofuel conversion system, which travels to hurricane-hit ports and converts debris into biofuels. For a 30MW plant, the break-even per-gallon revenue for profitability was found to be $5.28 per gallon of jet fuel for Fischer-Tropsch synthesis, $0.88 per gallon of heating oil for pyrolysis, and $1.07 per gallon of ethanol for fermentation.Using May 2019 US national fuel prices, the pyrolysis and fermentation plants were found to operate at a profit of $363.87 and $166.40 per dry ton of consumed hurricane debris respectively. A supply chain model was also created to calculate debris transport costs and evaluate the economic benefits of chipping debris directly in the field, which was found to be 24% more efficient than status quo stationary chipping operations. Water hyacinth is generated predictably and in huge quantities; however, the weight of water hyacinth is up to 95% water and it is thus inefficient to work with. Thus, we propose a novel roller-crusher harvester which grabs, crushes, and directly bags aquatic plants into digesters in-situ on the water. We find that an anaerobic digestion system with the proposed mechanical harvesting system could make a profit of $5.81 per ton of hyacinth, turning a costly problem into an economic opportunity.Hardware designs, prototypes, and on-water tests then show the viability of the roller-conditioner as a boat-mounted in-situ harvester-crusher. Ultimately, this work shows that careful design and evaluation of utilization systems could turn government aid and charity spent every year on debris and waterway cleanup into a profitable investment.
Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2019Cataloged from PDF version of thesis.Includes bibliographical references (pages 177-187).
DepartmentMassachusetts Institute of Technology. Department of Mechanical Engineering
Massachusetts Institute of Technology