Degree: Doctoral Student
Department: Mechanical & Industrial Engineering
Supervisor: Professor David Sinton
Supplementing or replacing fossil fuels with biofuels produced from sustainable sources is one approach to curb overall c emissions. Current biofuel practices have come under scrutiny, however, due to net inefficiencies and land use requirements. The ultimate model for production of biofuel is the natural photosynthetic process, i.e. direct utilization of solar energy to convert CO2 and water into biofuel. Harnessing this process in an energy efficient manner, however, is a global technological challenge. An emerging strategy for harnessing photosynthesis is the direct conversion of CO2 to biofuel using photosynthetic bacteria. Current photobioreactor strategies, however, suffer from two inherent weaknesses: (1) only a very small section of the reactor receives the appropriate light intensity due to poor light distribution; (2) only very low bacteria concentrations can be employed because flow is required to circulate bacteria through the section that receives the appropriate radiation. Consequently, large outdoor production plants are required that must be located in warm environments where they can operate at productive temperatures (> 20 C) year round – an unrealistic requirement in Canada. In this work, we suggest an alternate approach to light distribution that overcomes these issues. The concept is to cultivate photosynthetic bacteria in thin films on the surface of light guiding materials such as optical fibers. Cells on the surface of these light waveguides can siphon energy out of the guide for use in photosynthesis. By bringing light into the reactor space and delivering it to a film of densely packed cells, large volumes of optimally excited bacteria can be packed into a relatively small space. This strategy promises three-orders of magnitude improvement in areal productivity and overall power density, and importantly, enables sustainable solar biofuel generation in Canadian climates.