Wind, waves and sun
As Sandy Neil reports, moves are afoot to find greener energy sources for fish farming operations.
The fish farming industry relies heavily on diesel generators which, of course, cause CO2 emissions – contributing to global warming – that need to be phased out. But with what? This month, Fish Farmer looks at how green energy can provide power for aquaculture operations – from wind and wave energy to solar power.
“Aquaculture, like many other sectors, increasingly seeks to decarbonise and demonstrate strong environmental principles as countries, including Scotland, adopt net zero policies,” begins the Sustainable Aquaculture Innovation Centre (SAIC), as it sets out the challenges for the industry.
“Growth in this sector is constrained by geographic factors, such as the lack of availability of sheltered, inshore sites. This, alongside other factors, has encouraged many fish farms to move to locations further offshore. These need higher amounts of diesel to meet electrical power requirements, as they are off-grid. Fish farmers aim to reduce the need for diesel generators in order to increase sustainable practices and reduce both cost and emissions.
“For these reasons, there is a clear interest in renewable energy solutions within the industry. However, any renewable solution must ensure reliable power to protect fish health, offer energy storage options, and be a competitive alternative to diesel.”
There are different pros and cons for each alternative, the SAIC explains. “The reliability of power is of the utmost importance to fish farms. Loss of power for even one day can present problems such as disruption to feeding routines or loss of signals from sensors. Current options for energy include subsea cables providing mains power, solar panels, small wind turbines, hydrogen fuel cells, and ammonia fuel cells. Each of these faces unique challenges that can make their adoption in coastal Scottish waters difficult and expensive.”
Carnegie solar power unit
For example, while mains power supplied by a subsea cable is more reliable for nearshore farms, it is not an option for remote sites off the coast of Scotland, where there is not sufficient grid infrastructure. In addition, the industry is moving further and further offshore due to the lack of availability of inshore sites.
And while solar panels offer an affordable price, they do not produce enough power during winter months. Salmon is generally only farmed in cold waters in northern latitudes where sunshine is limited for half the year. Solar can also suffer badly from corrosion in a marine environment.
“Emerging wave and tidal technologies offer potential, although currently, they are comparatively expensive,” added the SAIC. “Most wave energy technology requires two-metre waves in height; a demanding requirement for traditional farms in sheltered areas and calmer swell. However, as farms increasingly move to more exposed, high-energy locations, wave resource levels should meet this requirement.”
Carnegie MoorPower unit
Who will rule the waves?
Back in 2023, the Norwegian trout farming company Svanøy Havbruk became the world’s first aquaculture business to use wave power to generate electricity, at the company’s site on the south side of Svanøy in the Vestland region.
A full-scale Havkraft N-Class wave power plant was installed close to the island of Svanøy. Havkraft developed two types of oscillating water column (OWC) power plants, the first being the Havkraft N-Class which is fitted for nearshore locations, while the second – dubbed Havkraft O-Class – is more suitable for offshore operations.
Now Scotland is taking a significant step towards sustainable energy for fish farming, with an innovative wave energy device called ZOEX, being developed by a company of the same name.
“ZOEX has the potential to revolutionise the way in which wave energy can be harnessed in small sea-states and be utilised to create cost-effective clean energy, replacing the use of CO2-emitting generators in off-grid locations,” says the company. “The ZOEX wave energy converter can be mounted directly onto feed barges, replacing CO2 emitting diesel generators and providing a clean, reliable and robust energy source.
“The ZOEX can also be installed in a variety of different locations, such as breakwaters, harbour, and offshore wind turbine mono-piles where its patent-pending double link arm mechanism acts as a gearing mechanism to enhance the effectiveness of the Power Take off system, generating more energy.”
Ash Penley, ZOEX founder at the opening event
The founder is Ash Penley, an award-winning businesswoman from Aberdeen. She told us: “I have named the wave energy converter after my children’s names, Zoe and Alex. Zoe means ‘life’ in Greek and we hoped to bring livelihood to community and businesses with clean energy from waves… Alex means ‘defender of man’, and I mixed the two names and came up with ZOEX.”
ZOEX has teamed up with Sealand Projects Ltd, an engineering house in Aberdeen with experience in offshore installation of oil and gas, and renewable energy projects. A study, funded by the SAIC and Scottish Enterprise, aimed to confirm whether mounting the ZOEX Wave Energy Converter (WEC) to a suitable feed barge could provide sufficient clean electrical power to meet the needs of a typical fish farm in Scotland.
The ZOEX WEC, explains SAIC, “…is a modular wave energy converter that can be attached to marine structures to provide cost-effective, reliable, and clean power to help reach sustainability goals. The device is a simple hinge plus float, designed to be attached to the platform of a marine structure.
“A rubber fender moves up and down as a wave-actuated body. An electro-mechanical generator captures the fender’s movements. The design incorporates a mechanism to enhance power production in small waves while mitigating end-stop problems in large waves, making it suitable for low and high sea states.
“ZOEX can be regarded as a trickle charger of battery systems, topping up and always keeping the batteries full, reducing a fish farm’s dependence on diesel while reducing costs and carbon emissions.
“A levelised cost of energy (LCOE) analysis estimated the energy would cost in the range of £223-£600 per megawatt hour, although this will differ from site to site. This estimate accounts for capital expenditures such as equipment and project development, as well as operating expenditures such as maintenance, insurance, and other annual charges.
“In the short term, the device encounters higher costs. However, the WEC results in lower long-term expenditure, as waves are a free energy source and the generator requires minimum maintenance. Additionally, initial costs can be reduced even further with multiple government grants and programmes available to assist with implementing renewable energy solutions.”
The report concluded: “This study achieved its objectives and illustrated that the ZOEX WEC is a good value proposition to customers, costing less than or equal to diesel alternatives. Further, the WEC produced zero harmful emissions to the atmosphere. Therefore, the study has concluded that the ZOEX WEC is a promising net-zero solution that is technically feasible and commercially attractive to the aquaculture industry.”
The first ZOEX device was commissioned at Port of Aberdeen in June 2024, and was celebrated with a launch event where representatives from industry and government could witness the device working.
Waves down under
Meanwhile on the other side of the world, Australian company Carnegie Clean Energy is also fitting wave energy generators to fish farm feed barges. “Carnegie Clean Energy developed MoorPower, a product that leverages the core principles of the CETO technology to create an innovative wave converter system specifically designed for offshore energy demand applications,” it explains.
Carnegie has designed, installed and operated a scaled demonstrator of the technology just offshore from its headquarters and research facility in North Fremantle, Western Australia. The A$3.4m (£1.74m) project is delivered with funding support from the Blue Economy Cooperative Research Centre (CRC).
“The MoorPower project signifies a crucial step in validating the technology and exploring large-scale implementation on aquaculture vessels,” Carnegie Clean Energy told Fish Farmer. “A scaled demonstrator, featuring three power take-off units connected to the seabed, showcases the technology’s viability. These units efficiently harness ocean energy as the barge moves with the motion of waves, driving onboard generators to produce ready-to-use electricity. The demonstrator project incorporates real-time data transfer, providing critical information on wave height, wind conditions, and energy generation.
“The MoorPower Demonstrator was deployed and entered operation in January 2024 and has provided over 2,000 hours of operational data during its initial operational phase. It was brought back into port for routine inspection and planned maintenance in April 2024.
“This initial operational phase was primarily in calmer months, which enabled the team to monitor the MoorPower modules and ensure they were functioning as engineered prior to the more significant anticipated sea conditions of the winter months.
“Overall, the recent data gathered on the Demonstrator combined with recent data gathered from an operating feeding barge in Tasmania provide confidence that the Commercial MoorPower System will perform as expected and can deliver significant decarbonisation (reduced diesel requirements) and other benefits for operating feeding barges.”
In June, the company redeployed the MoorPower Demonstrator at the offshore site for winter tests.
Clean energy system developed by AKVA, Kverneland Energi and Inseanergy
Here comes the sun
Developments in solar energy are also forging ahead. Earlier this year, we heard about a project to harness floating solar panels to power Chilean fish farming operations, led by a team from AKVA, Kverneland Energi, and Inseanergy. AKVA said: “The initiative aims at precision farming with minimal emissions, incorporating advanced hybrid battery systems, solar power plants, software, and control systems tailored to meet the challenging demands of sustainable aquaculture.”
Christian Gerardo Schäfer Oyanedel, General Manager in AKVA group Chile, explained: “This is a system of floating solar energy production that generates 100% emission-free green energy. The solar power plant will work as a ‘floating generator’ being able to produce as much as 290 Kwh. In combination with a battery pack and water feeding, we can reduce the running time of the diesel generator by up to 90% on a typical fish farm.”
Christian Gerardo Schäfer Oyanedel, AKVA Chile
“A hybrid energy system offers many advantages,” elaborated Kverneland Energi. “You reduce the use of diesel and drastically cut CO2 emissions. Noise is reduced both on and around the fleet. You need fewer generators, which saves money on maintenance and operation. And the investment pays off quickly.
“In December 2019, we installed AKVA Hybrid track systems on Mortenlaks’ feed fleet to reduce diesel overuse and CO2 emissions. The battery pack has a storage capacity of 173 kWh and a maximum output of 120 kW. Annual diesel savings: 68,500l. In April 2019, the feed fleet at Selsøyvær had an AKVA hybrid package installed to reduce running time on the generator, reduce diesel consumption, noise and exhaust on the fleet. The battery pack has 158 kWh storage capacity and has a maximum output of 142 kW. Annual diesel savings: 68,500l.”
Green power on land
For the much easier application of powering facilities on land, like hatcheries, how far has the industry progressed, in Scotland and elsewhere? In the EU, the Kingfish Company is “on a mission to promote sustainable aquaculture”, it says. “Based in the Dutch province of Zeeland, Kingfish Zeeland taps into the pristine marine estuary water of the Eastern Scheldt, a Natura 2000 nature reserve, to deliver a healthy, antibiotic-free premium delicacy: the Dutch yellowtail.
Kingfish Zeeland’s RAS plant
“Our primary energy source is 100% renewable electricity – wind-powered and solar.” Kingfish Zeeland also deploys heat exchangers, “to minimise energy use for heating, our warm outflow water transfers heat to our incoming water through a state of the art heat-exchange system custom designed for marine water use. By using sea water, we don’t waste a precious and rare resource.”
Closer to home, Scottish Sea Farms, which prides itself on its sustainable approach to salmon farming, saw its Barcaldine Hatchery recognised in the Carbon Reduction Award category of the Scottish Green Energy Awards in 2021. Among the greener approaches in operation is a 600kw biomass energy system. Supplied by AMP Clean Energy, it uses locally sourced, sustainably managed woodchip to provide the 17,500 sqm Barcaldine Hatchery with much of its heat and hot water, saving 683 tonnes of carbon annually compared with oil. That’s the equivalent of six million miles by car.
The progress may be impressive, but is it enough? Under the 2015 Paris climate agreement, 197 countries – including the UK – agreed to try to limit global temperature rises to 1.5C by 2100. To achieve this, CO2 emissions need to fall by nearly half by 2030 and reach net zero by 2050, according to the UN’s climate body, the IPCC. But these emissions remain at record highs.
The US has pledged to reach net zero by 2050, but that may be revised. In the run-up to the US presidential election, Donald Trump continues to summarise his energy policies with a slogan: “Drill, baby, drill.” If he wins, the world will have to go further and faster to meet its crucial target.
