© Petur Gunnarsson
One of the most pressing challenges faced by the global aquaculture industry is the mounting pressure to abandon traditional aquafeed ingredients, especially those that rely on reduction fisheries, in favour of ingredients with fewer environmental impacts. Indeed, it is hard to justify the use of wild fish populations as a resource for aquafeeds given that the aquaculture industry claims to provide a sustainable alternative to capture fisheries.
In light of this, many commercial aquafeed companies have invested significant time and money into the development of alternative, often plant-based, feeds. However, something these alternatives lack is a natural, stable and low-impact source of omega-3 fatty acids, in particular eicosapentaenoic acid (EPA) and docosahexanoic acid (DHA). So explains Isaac Berzin, founder and CTO at Vaxa Technologies – an Icelandic company seeking to revolutionise the aquaculture industry through the power of carbon negative microalgae.
Microalgae and geothermal energy – the dream team
Given that the omega-3 fatty acids so prized in fish oil are originally synthesised by microalgae – which forms the bottom link in most marine food chains – it is a logical next step to cut out the middleman and feed the microalgae directly to farmed fish. However, to ensure this is truly sustainable it’s best to use a process that doesn’t rely on finite resources such as water and energy sourced from fossil fuels to grow the algae, Berzin states.
Seeking to avoid these pitfalls, Berzin and his team at Vaxa established their microalgae culturing facility next to one of the largest geothermal power plants in the world. The output streams of the power plant provide for all the needs of the Nannochloropsis microalgae farmed by Vaxa – including light, water and carbon – significantly reducing the carbon footprint of production in comparison to other microalgae producing operations.
“This is the only process that I know of that's carbon negative, which means that the carbon that the algae eats is more than the CO2 that is omitted by cultivating it from the energy usage and fertiliser,” Berzin explains.
Seeking to validate the performance of the Nannochloropsis oil, feed trials were undertaken to compare the algal oil – both as a feed coating and extruded ingredient – to traditional omega-3 sources. The trials showed that, while salmon growth rates were similar between experimental and reference diets, omega-3 accumulation was significantly increased in fish fed on the algal oil-coated feed, compared to those fed on fish oil-coated feed.
© Petur Gunnarsson
What about the waste?
Key to achieving Berzin’s goal of supporting the production of carbon neutral farmed salmon is Vaxa’s resourceful use of its algal biomass by-products. Due to the indigestibility of the Nannochloropsis cell wall, the omega-3s are extracted as an oil, leaving behind a nutrient-rich biomass with a very low carbon footprint. This, Berzin proudly states, has been developed into a biostimulant for terrestrial agriculture.
“A significant chunk of carbon is sequestered in the soil, and all the microorganisms that live in the soil, and biostimulants are a very small class of materials that have this quality of enhancing soil organic carbon sequestration,” he explains.
“Looking at the overall picture, what do we have? We have algae production which is carbon neutral by nature, and you have a product which is an omega-3-rich oil, and then, because the waste product creates a carbon sink, this oil is carbon negative,” he adds.
According to a lifecycle assessment, taking into account transport, spreading, and uptake, a distribution system consisting of four agricultural drones applying the biostimulant across the period of one year could achieve net carbon sequestration of 436,981 CO2 equivalent – that’s 45.9 tonnes of CO2 equivalent per kg of biostimulant – according to a preliminary literature study for soil organic carbon uptake from biostimulants and a lifecycle assessment conducted by external consultants.
© Petur Gunnarsson
Towards a carbon neutral salmon
Carbon emissions are one of the most complex challenges faced by the aquaculture industry, as researchers and producers strive to achieve farming practices with progressively low environmental impacts. A large aspect of this challenge is often one step removed from the farmer, with a significant portion of the carbon emissions associated with salmon farming coming from the feed supply chain. Berzin hopes to overcome this with the incorporation of Vaxa’s algal oil into aquafeeds. And, although the product may not be price-competitive with traditional aquafeed ingredients, when considering the importance and intrinsic value of carbon sequestration, Berzin is confident that Vaxa can hold its own.
“Carbon neutral salmon can exist, and the good news is, because of the carbon intensity of the product, you can even use it as a polishing feed towards the end of the salmon’s lifetime, and you can still reduce the carbon footprint significantly. Because it can be used in this way, it doesn’t necessarily influence the total production cost of the fish,” he explains.
“We are in stages of collaboration with several large salmon producers and, because the feeding time could be relatively short, we don't expect the pilots to be that time-consuming. I really do hope that in this year we could have the first carbon neutral salmon produced using our solution,” Berzin adds.
With the industry currently producing between 2.5 – 7.5 kg CO2 equivalent per 1 kg of farmed salmon, this creative solution to a pressing industry challenge could be revolutionary, if it catches on among commercial producers. Until that point, Berzin hopes to expand Vaxa’s operations globally, with aims to establish clean energy-fuelled microalgae farms to facilitate sustainable feed production around the world.
“I think there's a benefit for the environment, a benefit for the consumer in elevated omega-3 levels, and a benefit for the producer of the salmon because it can have a branded carbon neutral salmon at a reasonable cost. We think it's great news for the industry and we're already talking to several commercial partners to actually pilot it and release it and bring this kind of innovation to market,” Berzin concludes.
