UK firm looks to combat climate change by farming ocean seaweed

Seaweed farmed out in floating paddocks in the deep ocean can play a key role in removing carbon from the atmosphere and mitigating climate change. This is the argument of Seafields, a UK-based company that is looking to domesticate and grow sargassum, a type of large, brown, free-floating algae. After using robots to harvest this seaweed for its useful resources – which can be used to make products from fertiliser and organic concrete through to cosmetic emulsifiers and the raw material for alternative plastics the rest of the crop will be compressed and sealed into special bales and dropped into the ocean. Sinking all the way to the bottom of the sea floor, these bales will lock away carbon for millenia, helping to offset greenhouse gas emissions. The principle is the same as growing trees to combat climate change – with photosynthesis using up carbon dioxide to create new biomass – except for the fact that sargassum grows much faster, doubling in size every two weeks, and doesn’t take up precious space on land.Seafields’ director is the impact investor John Auckland, who became interested in sargassum’s potential for carbon sequestration after hearing marine ecologist Professor Victor Smetacek, now the firm’s chief scientific adviser, discussing it on a podcast.Mr Auckland told Express.co.uk: ‘It was a lightbulb moment for me. I’d never heard of anything that could operate either in a 1,000-year plus sort of permanence or at the gigaton plus scale.’All those years I’d spent looking at these things that were making tiny claims towards solving the climate crisis, and then there’s a single project that comes along and is talking billions of tonnes and thousands of years.’It just blew my mind. I was immediately hooked. [We] got Victor on a call within a week of us all watching this podcast – and, you know, the rest is history.’ Seaweed grown out in floating paddocks in the deep ocean can play a key role in sequestering carbon (Image: Seafields) Sargassum is a type of large, brown, free-floating algae – which grows fast (Image: Seafields)Key to Seafield’s plans to grow sargassum in the ‘desert’ of the deep ocean gyres – areas where ocean currents from large circular patterns – will be fertilising the water in which the seaweed will grow.To do this, they intend to tap into the vast quantities of nutrients trapped in depths using a device called a ‘Stommel pipe’, also known as a ‘perpetual salt fountain’.Marine ecologist and Seafields chief scientific advisor Professor Victor Smetacek explains: ‘A Stommel pipe is that connects the colder, nutrient-rich water with the surface, warmer – but also saltier – water.’In the tropics, the upper layers of the ocean tend to be saltier than it is at depth as a result of the evaporation of water from the surface. And in ocean deserts, the seawater is heavily ‘stratified’, or layered, and there is little vertical motion.However, if you place a giant pipe – and Seafields are planning ones that are 1,300-odd feet tall – between the different layers and fill it with deep water, it creates an upward flow.READ MORE: Climate emergency now at ‘code red’ say scientists calling for action Seaweed grown in the deep sea will be baled and sunk – storing carbon for millenia (Image: Seafields) Seafields will use a so-called Stommel Pipe to bring up deep nutrients (Image: Seafields )The pipe works because the water in the pipe is less saline than the water outside it, and so by extension more buoyant. Once the flow is started, it continues pretty much indefinitely – or, at least, for as long as the salinity differences remain.Prof. Smetacek and his colleagues are actually planning to take this concept one step further – having a double pipe through which the warm surface water can also sink, being cooled by the rising water from below.He added: ‘These counter-flow Stommel pipes have two advantages. It not only brings nutrients to the surface […] but it also takes oxygen down to the depths.’You could release this water in the so-called oxygen minimum zones – the dead zones that would arise under any kind of farming activity on the surface. So, you could oxygenate that.’DON’T MISS:Mysterious white blob washed up on Cornish beach eludes identification [REPORT]Britons told energy saving log burners now ‘increase health risk’ [ANALYSIS]Defence system could ‘change Ukraine war’ and devastate Russia [INSIGHT] Seafields plan to grow their sargassum in deep ocean gyres (Image: Seafields)Seafields is operating in a proof-of-concept stage, working to show that their business model and the science that underpins it is indeed commercially viable.Alongside selling the raw materials harvested from their sargassum crop, the firm will make its money by producing carbon credits – certificates sold to companies to offset their own greenhouse gas emissions.First, however, the firm must show that they can domesticate and contain their seaweed. To this end, the firm have recently been testing designs for modular barriers – the fences of their paddocks, if you will – off the island of Saint Vincent, in the Caribbean.And next Spring, Mr Auckland explained, Seafields will be undertaking environmental impact assessments off the coast of Barbados to show that their bales remain intact on the seafloor.He added: ‘We will sink our first bales down to 4,000 metres [2.48 miles]… on these landers that allow us to monitor everything that’s going on.’We need to be able to demonstrate their degradation rates and so on to be able to monetise our primary revenue source, which is selling carbon credits.’With this complete, the firm is hoping to set up a pilot farm in the Caribbean sometime next year, and move out to the deep sea within three years. Because the farms are modular, it will be easy to scale them up, Mr Auckland explained.According to Prof. Smetacek, there may be another environmental benefit to farming seaweed – it might help remove plastic and microplastic pollution from the ocean.He said: ‘Sargassum exudes slime. So, the microplastics will be picked up in that slime.’We haven’t done the experiments here,’ he admitted, ‘but you also imagine that it could happen. We could not only get the pieces of plastic that could be seen by the naked eye.’If this does turn out to work, the sargassum farms could prove a triple threat – sequestering carbon, picking up plastic pollution and helping provide a replacement for petroleum-based plastics. But, as Prof Smetacek himself concluded: ‘We have to save the planet!’