Current and Future Energy Use for Atlantic Salmon Farming in Recirculating Aquaculture Systems in Norway

In recent years, the land-based production phase is extended in the Norwegian salmon farming industry.
This is a consequence of problems with sea lice and pathogens in conventional production in open-net
pens, as well as a wish to optimise production. The land-based production now mainly takes place in
Recirculating Aquaculture Systems (RAS), which allow for control of the rearing environment, low water
demand and reduction in nutrient discharge. However, high energy use is identified as a major drawback.
Few previous studies have focused on energy use and efficiency in RAS, which is of increasing importance
for the Norwegian salmon farming industry. This study evaluates the current and future energy use for
the production of Atlantic salmon, smolt and post-smolt in RAS facilities in Norway. The current energy
use for smolt and post-smolt production is analysed based on data collected from Norwegian RAS facilities,
while an energy model is developed to evaluate future energy use for large post-smolt production
and salmon grow-out in RAS.
The data collected show that energy use is highly variable across RAS facilities. The on-site energy use for
production of 1 kilo live-weight smolt ranges from 5.1 to 12.8 kWh, with a mean of 8.8 kWh. The current
average energy use is about twice as high as previous estimates, as well as estimates by the proposed
model. This study demonstrates that the implementation of available energy efficiency measures, can in
average reduce energy use by 30%. Additionally, if biomass production is optimised, the energy use can
be lowered to 4-5 kWh/kg, which is the level of previous estimates.
The simulated on-site energy demand for production of 1 kilo live-weight post-smolt of 1 kg is 3.4 to
5.4 kWh. Energy use for salmon grow-out to market-size in RAS is estimated to be between 6 and 10
kWh per kilo live-weight. The analysis of scenarios for future biomass production in RAS indicates a
considerable total energy demand in future. These projections assume that the RAS facilities are energy
efficiently operated and designed. However, the data on energy use in Norwegian RAS facilities show that
this is currently not the case. Hence, an increased focus on energy efficiency is needed for RAS facilities
in Norway to avoid a situation where high energy use, power grid capacity and associated costs become
a barrier for future growth in land-based aquaculture.