Seaweed Innovation: How PlantSea is Transforming Packaging with Biodegradable Polymers

Published on 2025-02-28

Startup Story

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PlantSea refines seaweed into a biodegradable polymer, replacing PVA plastics. With strong industry demand, the company is scaling production globally to deliver cost-effective, sustainable packaging solutions.

 

 

The journey of PlantSea began in a small seaside town called Aberystwyth, in Wales. It all started as an experiment—just a few friends collecting seaweed from the beach and exploring its potential. I’ve always loved the ocean; I swim regularly and feel deeply connected to nature. That passion, combined with the scientific expertise of my two co-founders, led us to the idea of using seaweed to create a sustainable alternative to plastic. My background is in marketing and business, while my co-founders are scientists, so together we formed the perfect team to turn this idea into something real. At first, it was just a project, a challenge we set for ourselves—could we make a plastic replacement from seaweed? But as we dug deeper, we realized that this wasn’t just an experiment; it was a genuine opportunity to tackle one of the world’s biggest environmental problems. That’s how PlantSea was born. Our mission is to accelerate the transition to biodegradable biomaterials, offering a nature-based solution that aligns with the growing demand for sustainable alternatives. Seaweed is a game-changer—it grows rapidly, doesn’t require freshwater or fertilizers, and naturally biodegrades without leaving harmful residues. This is what excites me most: the potential to replace single-use plastics with something that works in harmony with the environment rather than against it.

 

Addressing the Plastic Pollution Crisis with a Natural Alternative

Plastic pollution is one of the most pressing environmental issues of our time, and while we can’t solve every plastic problem overnight, we’ve developed a solution that tackles a specific and critical area. We’ve created a natural polymer derived from seaweed, and what makes it unique is its ability to form an ultra-thin, water-soluble film that completely dissolves without creating microplastics. Our material is designed to replace traditional water-soluble plastics like polyvinyl alcohol (PVOH or PVA), which are widely used in products such as laundry detergent pods, cleaning product sachets, cosmetics, food packaging, agricultural fertilizers, and even industrial water treatment chemicals. The issue with PVA-based plastics is that while they are marketed as biodegradable, emerging studies suggest that they may not be as safe as advertised. Many of these plastics break down into smaller fragments, releasing persistent chemicals into water systems—chemicals that are difficult to filter out, even in advanced water treatment plants. This raises concerns about the long-term impact on both human health and ecosystems. Our seaweed-based film, on the other hand, naturally biodegrades without leaving behind these "forever chemicals," making it a safer, more sustainable choice. Fortunately, many major brands that currently rely on soluble plastics are actively looking for better alternatives. They recognize the growing consumer demand for sustainable solutions and are eager to eliminate problematic plastics from their supply chains. This shift in mindset is creating a strong market pull for our technology, and we’re excited to be at the forefront of this transition. By offering a truly biodegradable, non-toxic replacement, we’re not just creating a product—we’re helping to redefine the way industries think about materials and sustainability.

 

Turning Seaweed into a Cost-Effective, Biodegradable Plastic Alternative

At PlantSea, we refine raw seaweed—sourced mainly from Scotland and Ireland—into a natural polymer through our patent-pending process, creating a water-soluble film that dissolves completely without leaving microplastics or harmful residues. Unlike traditional PVA-based plastics, which claim to degrade but may leave behind persistent chemicals, our material offers a genuinely biodegradable alternative. A key challenge in sustainable materials is cost, but we’ve optimized our process to match the price of conventional plastics, making large-scale adoption feasible for industries like home care, cosmetics, and agriculture. One of our most successful pilots was with Olow, a Welsh cosmetics brand, where we encapsulated shampoo and hair oil in our film, receiving excellent consumer feedback. We’re also working with major brands in the laundry and home care sectors, currently entering commercial agreements that will help scale our solution to replace single-use plastics across multiple industries.

Scaling Up for a Sustainable Future

Customer feedback has been invaluable in shaping PlantSea’s development, especially as we work with major brands and manufacturers. As a marketer at heart, I love understanding what businesses and consumers truly need—there’s a clear demand for sustainable alternatives, but they must be cost-effective and fit seamlessly into existing supply chains. This insight has driven us to refine not just our polymer, but also how we deliver it, ensuring it integrates smoothly into large-scale manufacturing. Looking ahead, our focus is on scaling up production. We’re working with a biorefinery in Wales and expanding internationally to increase capacity from hundreds of liters to thousands, eventually reaching industrial-scale volumes. Our business model is to supply the polymer to film manufacturers, and we’re currently building strong partnerships in Asia, where film manufacturing is a major global industry. Over the next 12 months, our key milestones are centered on these scale-up efforts, ensuring we can meet growing demand and bring our seaweed-based solution to market at a truly impactful level.

About the author

Rhiannon Rees