Optimal dynamic operation of microalgae cultivation coupled with recovery of flue gas CO₂ and waste heat

This work addresses integration of microalgae cultivation with power production for the recovery of flue gas waste heat and CO₂. The economics of supplying CO₂ to an outdoor open pond for cultivating microalgae are compared for pure CO₂ gas and flue gas injection scenarios. Cooling of the flue gas is modeled for direct-contact heat transfer arrangement. The economic advantage of employing waste heat recovery using indirect-contact heating of the open pond water is investigated as well. An optimization problem is formulated to determine the optimal monthly operations of the open pond and heat exchangers under each scenario. The flue gas injection scenario is found to be more economical with an improved annual harvest compared to the pure CO₂ gas injection case. Waste heat recovery is shown to slightly increase the annual harvest, but is also uneconomical due to the high capital cost of the heat exchanger.