Date of Award:

2014

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Mechanical and Aerospace Engineering

Advisor/Chair:

Jason Quinn

Abstract

Traditional terrestrial crops are currently being utilized as a feedstock for biofuels but resource requirements and low yields limit the sustainability and scalability. Comparatively, next generation feedstocks, such as microalgae, have inherent advantages such as higher solar energy efficiencies, larger lipid fractions, utilization of waste carbon dioxide, and cultivation on poor quality land. The assessment of microalgae-based biofuel production systems through lifecycle, technoeconomic, and scalability assessments has been forced to extrapolate laboratory-scale data due to the immaturity of the technology. This type of scaling leads to large uncertainty in the current near-term productivity potential and ultimately the results from modeling work that rely on this type of modeling. This study integrated a large-scale validated outdoor microalgae growth model that utilizes 21 species and reactor-specific inputs that accurately account for biological effects such as nutrient uptake, respiration, and temperature with hourly historical meteorological data from around the world to determine the current global productivity potential. A global map of the microalgae lipid and biomass productivity has been generated based on the results of annual simulations at 4,388 global locations spread over the seven continents. Maximum annual average yields between 24-27 m3·ha-1·yr-1 are found in Australia, Brazil, Colombia, Egypt, Ethiopia, India, Kenya, and Saudi Arabia with the monthly variability (minimum and maximum) yields of these locations ranging between 14 and 33 m3·ha-1·yr-1. A scalability assessment that leverages geographic information systems data to evaluate geographically realized microalgae productivity, energy consumption, and land availability has been performed highlighting the promising potential of microalgae-based biofuels compared to traditional terrestrial feedstocks. Results show many regions can meet their energy requirements through microalgae production without land resource restriction. Discussion focuses on sensitivity of monthly variability in lipid production compared to annual average yields, biomass productivity potential, effects of temperature on lipid production, and a comparison of results to previous published modeling assumptions.

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