Microalgae production cost in aquaculture hatcheries

P.C Oostlander,J Van Houcke,R.H Wijffels,M.J Barbosa

doi:10.1016/j.aquaculture.2020.735310

Abstract

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 (Yx,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 Yx,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.

Highlights

In the past decade the use of microalgae for aquaculture has increased because of the importance of microalgae for the quality aquaculture feed (Borowitzka, 1997; Conceição et al, 2010; Shields and Lupatsch, 2012; Shah et al, 2018)
These cost prices are in the order of 100× higher than numbers described by Ruiz et al but describe algae production on a much smaller scale number described by Ruiz at 100 ha scale (Ruiz et al, 2016)
As most of the cost price is attributed to operational expenditure (OPEX), there is a large potential for cost-price reduction by reducing these operational costs

Summary

Introduction

In the past decade the use of microalgae for aquaculture has increased because of the importance of microalgae for the quality aquaculture feed (Borowitzka, 1997; Conceição et al, 2010; Shields and Lupatsch, 2012; Shah et al, 2018). The quality of feed is linked to mortality rate of fish larvae, development rate, egg viability and reproductive success of copepods among others (Abate et al, 2015; Knuckey et al, 2005). It has been shown that using fresh microalgae as feed for oysters leads to higher product quality than what is achieved with processed algae products such as algae paste or flocculates (Knuckey et al, 2006). Aquaculture 525 (2020) 735310 different algal species. Combining multiple different species of freshly produced algae can create an optimized nutritional composition for the use in aquaculture (Brown et al, 1997)

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