Microalgal biomass is considered to be a promising renewable energy source to replace fossil fuel given its simple growth mechanism and high productivity per unit area. Nevertheless, microalgal biorefinery still has a long way to go before it is fully commercialized owing largely to the high cultivation cost of microalgae. Open raceway pond (ORP), which is one of the oldest and simplest bioreactor types, is known to be the most suitable form of the bioreactor for large-scale production given its low operation cost and easy scale up characteristics. However, as the biomass culture is exposed to the outside environment, variabilities in the productivity can be severe, especially due to the variations in the environmental conditions like temperature. Therefore, in this study, the idea of equipping the ORP with a heat exchanger using industrial waste stream as a heat source is introduced as a strategy to maintain high productivity all year round. For evaluating its economic benefit, a mathematical model is established, and the optimal operating condition that maximizes the economic efficiency of the cultivation system is determined.