Fertile land from fertile seas

Professor Mike Allen and the PhycoMExUK team are working to convert problematic seaweed blooms into opportunity. Using innovative technologies and hydrothermal processes, the team are working to turn seaweed biomass into sustainable fertilisers and biofuels.

Every summer the Caribbean experiences a huge influx of free-floating seaweed which decimates local shorelines. Sargassum, a quick growing species, creates large floating clumps in the appropriately named ‘Sargasso Sea’, a region of the Atlantic Ocean where multiple currents meet. The largest annual raft, named the Great Atlantic Sargassum Belt (GASB), stretches over 8500km from Mexico to the west coast of Africa and is made up of over 20 million tons of biomass. The vast increase in growth is fueled by run-off from agricultural land in North America and the Amazon basin, as well as seasonal upwellings from Africa, bringing nutrients to the area.

At sea, the seaweed mats provide havens for multiple marine species and create strong oceanic ecosystems. The Sargasso Sea itself is a recognised ecological treasure trove. However, once washed ashore in excessive amounts, Sargassum can cause havoc for coral reefs and turtle nesting sites, as well as the added impact on the tourism industry, which decreases in affected areas due to the displeasing aesthetics and health problems associated with a surplus of rotting seaweed.

PhycoMExUK is a group of researchers from universities, scientific organisations and industrial groups in both the UK and Mexico who have teamed up to tackle the crisis using new hydrothermal liquefaction (HTL) techniques to turn the seaweed into useful products. The seaweed is subjected to high temperatures and pressures and results in four output fractions being created; CO2 gas, bio-crude oil, aqueous fraction (containing nutrients) and a solid char. The fractions can be stablilised and used as fertilisers, biofuels and stock chemicals.

The process is favorable due to its ability to cope with wet and salty biomass, removing the need for expensive and time consuming washing and drying processes. Perhaps even better, the process can deal with plastic pollution and heavy metals, removing it from the ocean and recycling it into products along with the seaweed.

So far, the project has gained exposure in global webinars and conferences where scientists from all over the world get together to share their work. The University of Exeter was recently invited to join the Sargasso Sea Commission (SSC) as a result of the team’s work. The commission works to protect the Sargasso Sea and find solutions to the increasing problems arising from problematic blooms.

Having investigated the ideal reactor conditions for processing Sargassum, the team are now conducting plant trials on the aqueous phase fertilisers both in the UK and Mexico.

Follow the project’s work here.

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