Improving Algae Photobioreactor Energy Efficiency Through Active Irradiance Control for Dynamic Carbon Dioxide Fixation

Abstract

For my Mechanical Engineering senior capstone, I developed and experimented with a 40-liter Chlorella vulgaris algae photobioreactor testbed for carbon dioxide removal. It responds to elevated levels of carbon dioxide, while reducing energy consumption during nominal operation. Energy efficiency is important for future space missions but must be achieved without sacrificing mission safety. In my photobioreactor, the LED lighting and circulation pump account for nearly all of the system energy consumption, at 75% and 23% respectively. I reduced energy consumption by controlling the bioreactor light levels in response to varying carbon dioxide levels. Experimental results indicated that the controlled photobioreactor responds effectively to a step increase in carbon dioxide, while using up to 57% less energy on lighting than an uncontrolled photobioreactor over the course of the response. The development of a photobioreactor that responds dynamically to carbon dioxide levels is an important step to reduce overall space mission cost.