Temperature, Evaporation, and Shading Effects on Algae in Experimental Paddlewheel Raceways

Abstract

Algal biodiesel commercial production is facing numerous challenges that could be summarized with one word “cost”. Researchers around the world are conducting experiments to optimize the cultivation of algae in order to shift the production of algae toward larger scale. The Regional Algal Feedstock Testbed (RAFT) project carried out experiments over a four-year period to record and optimize algae cultivation. During this period, as one of the objectives of this project, numerous models were developed to estimate algae productivity. This dissertation explains in detail the energy balance model used to estimate the culture water temperature based on meteorological data and how the parameters of this model were calibrated. It also provides a methodology that calculates solar shading for a given geometry and incorporates the reduction of light due to shading into the Huesemann Algae Biomass Growth (HABG) model, which is the algal productivity model developed and validated by the RAFT project. Three different hypotheses were suggested to describe how light is distributed between shaded and unshaded areas in the culture. Forty-five test runs were conducted by the RAFT project at the University of Arizona location. The experimental data collected in those experiments were used to calibrate and validate both temperature and shading models.