Predicting cost growth and performance of first-generation algal production systems

Estimates for algal production cost vary widely due to differing assumptions. Differences in assumptions make comparisons between proposed algal production systems difficult. Existing economic analyses have ignored potential capital cost growth and under performance of early generation algal production plants, which impact the preliminary unit cost of algal biofuels, which could affect investment decisions. Therefore the goal of this work was to compare the capital cost growth (ratio of actual to estimated cost), plant performance (ratio of actual performance to design), and unit cost growth factor (the ratio of cost growth to plant performance), of potential algal production pathways. Three production technologies were investigated: (1) open raceway ponds (ORP), (2) tubular photobioreactors (PBR), and (3) systems coupling photobioreactors to open raceway ponds. The greatest cost growth (1.5–1.8) was estimated for PBR systems, while the lowest cost growth (1.2–1.4) was estimated for the ORP systems and coupled systems. Plant performance was estimated to range from 13% to 40% of nameplate capacity. These results imply that unit cost growth for algal biofuels could range from 3 to 14 times current predictions, and illustrates large hurdles facing algal biofuels technologies that have yet to be implemented at scale.