PDMS as a Novel Photobioreactor Material for Algae Biofuels

Abstract

Decarbonization of transportation is a critical step in reducing global greenhouse gas emissions. In theory, biofuels represent a sustainable fuel option that could help close the carbon cycle. In practice, however, crops used for biofuels demand valuable land and water resources, resulting in significant land use changes and competition with agriculture. Algae are a promising alternative to crop-based biofuels given that algae do not require potable water or arable land. However, despite their apparent environmental sustainability, algae biofuels are currently unsustainable economically. Production costs drive up the price of algae biofuels, limiting their competitiveness in a market dominated by relatively cheap fossil fuels. In this thesis, polydimethylsiloxane (PDMS) is explored as a novel photobioreactor material that could reduce these production costs. PDMS is transparent, flexible, and permeable to both air and water. Hence, PDMS allows CO2 to diffuse into the photobioreactor, thereby reducing the costs needed to pump CO2 within the system. PDMS’s permeability to water allows the material to self-regulate its temperature via evaporative cooling. This temperature regulation should enable a PDMS photobioreactor to maintain suitable growth temperatures even under elevated temperature conditions. Additionally, PDMS can be cast and cured into different shapes, allowing the PDMS to mold into complex geometries that can be customized to meet the residence time and mixing requirements of specific photobioreactors. The experiments in this thesis test the temperature regulation abilities of PDMS, characterize the flow within the system, and ultimately result in a fully functional PDMS photobioreactor prototype.