Microalgae production cost in aquaculture hatcheries

Microalgae are a crucial part in many aquaculture feed applications processes, mainly in hatcheries. Many aquaculture hatcheries maintain a small scale microalgae production facility in-house for the production of live feed. Microalgae are usually grown in non-automated bubble-column systems at unknown production costs. Other reactor systems or scenarios utilizing artificial light or sunlight and at different scales could result in a more cost efficient production processes. To determine the cost-price and cost-distribution of microalgae production facilities in Dutch aquaculture industry and identify the most efficient cost reducing strategies a techno-economic analysis for small scale microalgae production facilities (25-1500 m²) was developed. Commercially available reactors commonly used in aquaculture were compared; tubular photobioreactors (TPBR) and bubble-columns (BC) in two placement possibilities; using artificial light in an indoor facility (AL) and utilizing sunlight in a greenhouse (GH) under Dutch climate conditions. Data from commercial microalgae facilities in the Netherlands are used to model reference scenarios describing the cost price of microalgae production with state of the art technology in aquaculture for a biomass production capacity of 125 kg year⁻¹. The reference cost price for algae biomass (on the basis of dry matter) is calculated at €290,- kg⁻¹ and € 329 kg⁻¹ for tubular reactors under artificial light and a greenhouse, respectively and €587,- kg⁻¹ and €573 kg⁻¹ for bubble-columns under artificial light and a greenhouse, respectively. The addition of more artificial light will significantly reduce production costs (by 33%) in all small-scale systems modelled. Biomass yield on light (Y_x,ph) showed the largest effect on cost price when not considering a different scale of the production process. Process parameters like temperature control should be aimed at optimizing Y_x,ph rather than other forms of cost reduction. The scale of a microalgae production facility has a very large impact on the cost price. With state of the art technologies a cost price reduction of 92% could be achieved by changing the scale from 25m² to 1500m², resulting in a cost price of €43,- kg⁻¹, producing 3992 kg year⁻¹ for tubular reactors in a greenhouse. The presented techno-economic model gives valuable insights in the cost price distribution of microalgae production in aquaculture. This allows to focus research efforts towards the most promising cost reduction methods and to optimize existing production facilities in aquaculture companies to achieve economically sustainable microalgae production for live feed in hatcheries.