A model for utilizing industrial off-gas to support microalgae cultivation for biodiesel in cold climates

Lipids produced by microalgae are a promising biofuel feedstock. However, as most commercial mass production of microalgae is in open raceway ponds it is generally considered only a practical option in regions where year-round ambient temperatures remain above 15 degrees C. To address this issue it has been proposed to couple microalgae production with industries that produce large amounts of waste heat and carbon dioxide (CO2). The CO2 would provide a carbon source for the microalgae and the waste heat would allow year-round cultivation to be extended to regions that experience seasonal ambient temperatures well below 15 degrees C. To demonstrate this concept, a dynamic model has been constructed that predicts the impact on algal pond temperature from both bubbled-in off-gas and heat indirectly recovered from off-gas. Simulations were carried out for a variety of global locations using the quantity off-gas and waste energy from a smelter's operations to determine the volume of microalgae that could be maintained above 15 degrees C. The results demonstrate the feasibility of year-round microalgae production in climates with relatively cold winter seasons. (C) 2014 Elsevier Ltd. All rights reserved.