English title: Evaluation of synergetic effects of integrated recirculating aquaculture systems with water electrolysis units Norsk tittel: Evaluering av synergetiske effekter av integrerte resirkulerende akvakultursystemer med vannelektrolyseenheter

Abstract

Recirculating aquaculture systems (RAS) are developing rapidly as a pathway towards a more sustainable and efficient aquaculture industry. Such facilities allow for precise control of parameters involved in fish farming, such as oxygenation units for providing oxygen and replenish oxygen saturation levels in the recirculated water. In order to locally supply the oxygen demand to these facilities, water electrolysis technology may be a complementary solution of which oxygen and heat are secondary products, typically unutilized in conventional production units, in addition to the main product which is hydrogen. To study the synergetic effects of combining RAS facilities for Atlantic salmon and water electrolysis systems, three pre-defined case studies of varying sizes have been established with regards to the technical feasibility, impact on the production cost of hydrogen, as well as sensitivity analyses of relevant economical variables. Simulation of the alkaline water electrolysis process is also carried out through Aspen Plus software, and the varying oxygen demand during the growth of Atlantic salmon is modeled for each case study presented in this report. The three case studies show considerable economical benefits through scale-up of the combined facilities. A promising hydrogen production cost of 27.74 kr/kg H2 was achieved for the largest facility (case 3), producing more than 50 tonnes of O2 per day, where revenues from oxygen sales and district heating are included. A more detailed techno-economic analysis, optimization of the general concept, a study of including alternative energy sources such as wind and solar, as well as further work with the simulated process in Aspen Plus may be recommended for future studies of the established cases in this paper