Her research group are pioneering efforts to advance the sustainable bioeconomy. Central to their work is the development of seaweed-based biorefineries, using marine biomass as a renewable feedstock to address environmental and industrial challenges. © Dr Emily Kostas
“I’m always amazed by seaweed’s potential and the novel applications emerging from it," says Kostas, whose passion for the subject has only grown stronger as innovative startups and research breakthroughs continue to push boundaries.
In recent years, seaweed has emerged as a highly promising – and much hyped – raw material with a raft of potential applications. Yet, turning raw seaweed into valuable products requires sophisticated processing – and that’s where seaweed biorefineries come in.
“Seaweed is an amazing, sustainable, super feedstock,” says Kostas. “It has so many different applications: foods, fuels, packaging, carbon capture, cosmetics, pharmaceuticals... you name it, seaweed can tick the box.”
From volume to value: what is a seaweed biorefinery?
At its heart, a seaweed biorefinery aims to maximise value and minimise waste by sequentially extracting multiple high-value compounds from the biomass in an integrated, sustainable way – a method known as cascading biorefining. This model aligns perfectly with the vision of a circular bioeconomy, replacing petrochemical-based ingredients with renewable, low-carbon alternatives.
As Kostas and co-authors outlined in a foundational 2021 paper, this approach uses a mix of biochemical and thermochemical processing stages to convert as much of the biomass as possible into usable, market-ready products.
Biochemical processes at lower temperatures recover proteins and antioxidants with minimal degradation, while mid-range techniques extract polysaccharides like fucoidans and alginates, used in everything from cosmetics to bioplastics. At higher temperatures, thermochemical methods like pyrolysis and hydrothermal liquefaction convert the remaining biomass into bio-oils and biochars.
“Each temperature unlocks a new layer of value,” says Kostas, noting that combining both approaches maximises yields while balancing energy inputs and product integrity.
“One fascinating output from brown seaweed pyrolysis is its bio-oil containing hundreds of compounds. We identified compounds that have genuine pharmaceutical potential, like isosorbide for managing angina, dianhydromannitol as an anti-inflammatory and drug stabiliser, and 2-acetylfuran for antibiotic synthesis. This diversity is truly unique to brown seaweed,” she adds.
© Dr Emily Kostas
From batch to continuous: scaling up the science
Kostas and her research group are working on a key challenge in the field: scaling biorefineries from laboratory to industrial scale. Currently, many processes are run in batch mode – small, isolated steps that aren’t efficient or scalable.
“We’re trying to transition key processes from batch systems to continuous setups,” Kostas explains. “Think of it like a conveyor belt – biomass goes in at one end and products come out the other. It’s faster, cheaper, and more scalable.”
Yet scaling isn't straightforward. Processes perfected in the lab often fail at commercial scale, where yields can drop dramatically, and costs rise. Investment shortages compound the issue, with promising innovations frequently stuck in the infamous “Valley of Death” – a funding gap between proof-of-concept and commercial deployment.
While continuous processing is common in other industries, adapting it to seaweed’s unique chemistry – high water content, seasonal variability, and species differences – is technically demanding.
“It’s tricky, but we have to do it. If we can prove it works, it could significantly help the sector scale up,” Kostas reflects.
Why seaweed, and why now?
Seaweed stands out among renewable resources for several reasons. It doesn’t require fresh water, fertilisers or arable land. It grows quickly and can absorb carbon dioxide and excess nutrients from coastal waters.
Yet, as Kostas is well aware, the promise is matched by challenges.
“We’re still not producing enough biomass [in the UK] to feed a refinery all year round,” she says. “And even if we could, there’s the issue of stabilising and storing it – seaweed is 90 percent water and degrades quickly.”
Drying is a logical solution, but it’s energy-intensive and expensive. Transporting wet biomass over long distances is another logistical hurdle.
The bottlenecks
The path from ocean to product isn’t straightforward. Kostas identifies several bottlenecks:
- Infrastructure for scaling: the lack of large-scale farming and specialised processing facilities hampers growth and consistent production.
- Regulations and permitting: are fragmented and complicated across the UK’s devolved nations, making farm licensing expensive and time-consuming.
- Supply chain gaps: Farmers struggle to sell all their biomass; processors want year-round, consistent supply which is hard to guarantee.
The supply chain is currently unreliable, with inconsistent quality due to variable farming methods, species differences, and post-harvest practices.
“Seaweed composition changes with species, season, and even harvest location,” Kostas explains. “That makes standardising biorefinery processes incredibly difficult.” For the sector to scale, she argues, there needs to be better coordination and transparency across farms, as well as data-driven approaches to monitor biomass quality and yields. - Product and market development: There’s still uncertainty about actual demand for seaweed-derived products, requiring effective consumer education and competitive pricing strategies to compete with fossil fuel-based alternatives.
- Environmental unknowns: Large-scale seaweed farming has unresolved environmental impacts that must be carefully studied and managed.
- R&D and species optimisation: Many existing cultivation methods have been developed for a narrow range of species. As climate change shifts ocean temperatures and brings new or migrating seaweed species into UK waters, targeted R&D is needed to adapt farming techniques and refine processing approaches for a more diverse and resilient biomass supply.
- Investment challenges: Scaling up requires significant capital, but many investors are cautious due to limited data and past hype cycles in similar fields like microalgae. “It’s a bit of a chicken-and-egg situation,” says Kostas. “You need data to convince investors, but you need investment to generate that data.”
According to Kostas, infrastructure and supply chain bottlenecks remain the most critical challenges: "Even with strong demand and innovation, we need resilient infrastructure to consistently grow, harvest, transport and process seaweed at scale.”
Joining the whole value chain
A successful biorefinery must be part of a robust value chain: from sustainable cultivation, to efficient processing, to markets ready to absorb seaweed-derived products.
“We really need to consider the entire value chain, from feedstock supply to end users,” says Kostas. “At the moment, it’s quite disjointed.”
Regional cooperation within Europe could help. Kostas points to models where one large refinery could process seaweed from several countries, potentially making year-round operation feasible.
“That model could work,” she reflects. “But it would need collaboration, investment and probably EU support.”
© Dr Emily Kostas
What’s next?
Despite the challenges, Kostas is helping steer the UK’s seaweed sector toward a more viable future. In September she will supervise a PhD studentship project in collaboration with Notpla, the award-winning packaging company behind seaweed-based films and sachets, to test whether compounds from seaweed biorefineries could improve their materials.
“It’s one of the few studentship partnerships that’s directly industry-facing, with a clear application in sight,” she says. As part of the project, a PhD student will join her team to trial different seaweed fractions in real-world packaging formulations.
She’s also involved in the newly funded £14 million EPSRC Carbon-Loop Sustainable Biomanufacturing Hub (C-Loop), a national R&D initiative led by The University of Edinburgh focused on “bio-upcycling” industrial waste through cutting-edge bioprocessing and engineering biology. The Hub aims to explore a range of UK waste streams, and seaweed waste from the growing industry could play a key role in this broader push to replace fossil-derived inputs with renewable alternatives. Kostas was part of the interview team that helped secure the grant and will co-lead the work package on bio-upcycling seaweed waste into cosmetic and pharmaceutical products with Dr Jose Jimenez from Imperial College London. She is also the Chair of the Researcher Forum.
She’s also undertaking a series of stakeholder workshops across Scotland, Wales, London and Canada, bringing together researchers, farmers, policymakers and industry leaders to identify the sector’s most pressing challenges and opportunities.
“This will feed into a stakeholder engagement report and a policy paper with recommendations for seaweed biorefineries,” she explains. “Most importantly, it helps my research group align our work with real-world concerns, values, and societal needs.”
The critical step lies in translating insight into action.
“We need everyone working in the same direction , and we need to make it easier for people to enter this space with clarity on policy, process and potential,” she says.
For the sector to succeed, Kostas argues that the UK must start treating seaweed not just as a raw material, but as a strategic resource – one that can contribute to climate goals, bio-based industries and rural economic development.
That means full government support and recognition of seaweed as a sustainable UK resource, targeted investment, clearer policy frameworks, and improved national infrastructure across farming, logistics and processing.
“Seaweed biorefineries can be a core part of the UK’s bioeconomy , but we can’t do it alone. We need public and private backing, and a joined-up effort across the value chain. The science is there. Now it’s about building the system around it,” Kostas concludes.
