A North Wales company, founded in 2020, that makes biodegradable materials from seaweed to replace plastic in packaging such as laundry and dishwasher capsules.
PlantSea is a Welsh start-up that makes materials from seaweed to replace oil-based plastic. The company's materials are designed to be biodegradable and compostable, and they are aimed at uses such as packaging for laundry capsules and dishwasher tablets, food packaging, cosmetics and farming products. According to the Welsh Government, the materials dissolve without leaving microplastics. The company began with experiments using seaweed collected from the Welsh coast, and it is planning a biorefinery in North Wales to make seaweed extract itself.
PlantSea was founded in 2020 by Dr Rhiannon Rees, who is chief executive, Alex Newnes, the chief technical officer, and Gianmarco Sanfratello. The company came out of a student enterprise competition at Aberystwyth University, the InvEnterPrize event in April 2020. Its vision, in its own words, is "Turning the Tide on Plastic Pollution". A business directory entry says Dr Rees was inspired by plastic pollution she saw in Bali and by beach clean-ups, which led her to focus on packaging. The company says it wants to cut reliance on fossil-fuel plastics by using a renewable resource.
PlantSea is Welsh, and it is a UK company. A Welsh Government case study places it in St Asaph in North Wales, while an earlier article says it was a tenant at M-SParc, the science park on Anglesey, and worked with Bangor University. Its first product idea for packaging was developed with Tri-Wall, a cardboard manufacturer. The Welsh Government's innovation team has supported it through its SMART Flexible Innovation Support programme, and a partnership with Wrexham University gives the company a research scientist and access to specialist equipment. The company says it also wants to explore markets overseas, including the United Arab Emirates and Australia.
The Welsh Government case study says the headcount grew from 10 to 14 people, which gives a sense of the small, close team. Mr Newnes described the Welsh support as giving the company "the confidence to push forward with something genuinely new". In 2025 the company was ranked 60th in the Startups 100 index and was nominated for its sustainability award. We did not find a values page or a description of day-to-day culture, so we cannot say more than that it is a small, science-led team working with local universities.
Roles in a company like this include laboratory scientists and process engineers who develop the seaweed extracts, people who work with packaging and cosmetics customers, and the operations, finance and marketing staff of a growing business. If you like biology, chemistry or engineering and want to work on the coast of Wales rather than in a big city, this is a good example. Check the company's own website at plantsea.co.uk for current roles.
Website: www.plantsea.co.uk
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