Energy and resource consumption of land-based Atlantic salmon smolt hatcheries in the Pacific Northwest (USA)

Abstract

Abstract This paper evaluates the resource and energy requirements of six different types of land-based, hatchery production systems located in the U.S. Pacific Northwest: flow-through with a gravity water supply, flow-through with a pumped water supply, flow-through with pure oxygen, partial reuse system, partial reuse with heating, and a reuse system for the production of Atlantic salmon ( Salmo salar ) smolts. Key parameters used in the evaluation include direct energy, indirect energy, transportation energy, greenhouse gas emissions, and pollutant discharges. Power (electricity and natural gas) and feed energy accounted for the majority of the required energy for all the rearing option evaluated. The sum of the fixed capital and chemicals components accounted for less than 2–12% of the total energy budget for any rearing option. The energy efficiency (energy output/energy input) of the six options ranges from 0.97% for flow-through with pumped supply to 3.49% for the flow-through with gravity supply. The rearing options with the three highest energy efficiencies were flow-through with gravity supply (3.49%), partial reuse (2.75%), and reuse (2.64%). On a kg of smolt produced basis, the six rearing options showed a wide range in performance. The reuse system had the lowest water (2 m 3 kg − 1 ) and land (0.13 m 2 kg − 1 ) requirements and the third lowest total energy requirement (288 MJ kg − 1 ). The partial reuse system had the second lowest total power requirement (276 MJ kg − 1 ), a low land requirement (0.21 m 2 kg − 1 ), and moderate water requirements (33 m 3 kg − 1 ). The partial reuse with temperature control had the second highest total power requirement (657 MJ kg − 1 ) and land and water requirements similar to the partial reuse system without temperature control. The flow-through system with pumped water supply had the highest water (289 m 3 kg − 1 ), land (2.19 m 2 kg − 1 ), and energy requirements (786 MJ kg − 1 ) of any of the rearing options. By comparison, the flow-through system with gravity water supply had the lowest energy requirement (218 MJ kg − 1 ), a moderate land requirement (0.78 m 2 kg − 1 ), and a high water requirement (214 m 3 kg − 1 ). The ranking of the six rearing options based capital and operating costs are likely to be quite different from those based on energy, water, and greenhouse gas emissions.