Post date 12 Nov 2025 (original LinkedIn date)
Original LinkedIn version· 1,144 words
Written by John Lennon and Paul McCartney as part of ‘Sgt. Pepper’s Lonely Hearts Club Band’, and arguably popularised by Joe Cocker with his unforgettable, soulful rendition at Woodstock, please forgive my paraphrasing - but yesterday, I more than got by with a little help from my friends. Thank you Robert Gardner, Abbie Darroch, Raheem Mirza, Sacha Tchen, George Robson and Max Welch - for believing, for giving it a go, and for your hard work to make it happen.
UK Seaweed Symposium, 2025: bridging the Valley of Death
(or what we learned when Rebalance Earth convened 35 seaweed entrepreneurs, farmers, academics, consultants, investors, and ecosystem builders at the The Burrell Collection in Glasgow)
Yesterday, we gathered 35 diverse stakeholders across the UK seaweed value chain at the Burrell Collection in Glasgow for a half day-long intensive symposium on how to scale the seaweed industry. The feedback has been overwhelmingly positive - participants left describing the day as “thought-provoking,” “challenging,” and full of “glimmers of light.” But beneath that optimism lies a sobering diagnosis: the UK seaweed industry is stuck in the valley of death.
But the opportunity is so tangibly real
Let’s start with the good news. The numbers are compelling:
UK market potential: £297 million today → £603 million by 2033 (8.18% annual growth)
Global market potential: $9 billion → $18.4 billion by 2033
Investment potential: $100 billion needed by 2040, generating $313 billion of value and 200 million jobs
Farm-level returns potential: 22% IRR achievable at 10-hectare scale; 30× multiples possible in processing
Too much ‘potential’? Well let’s dive into the practicalities. Seaweed can serve multiple high-growth markets simultaneously, from food additives, biostimulants (where it achieves 17% yield improvements), animal feed with methane reduction properties, high-margin cosmetics, thru to emerging bioplastics. Unlike speculative climate tech, seaweed has intrinsic commodity value. It requires no land, no freshwater, no fertiliser. It’s the lowest-carbon food item we can produce at 0.13kg CO₂ per kilogram of dry weight.
Major corporations already understand this. Nestlé, Cargill, Danone, and Estée Lauder are investing. The market is growing. Demand exists. So why is the UK industry still stuck?
The ‘Valley of Death’: a coordination failure
Yesterday’s symposium attempted to throw light on a problem that doesn’t get enough attention: this isn’t a problem of opportunity or innovation. It’s a coordination failure.
Most UK seaweed farms cultivate just 0.5 hectares despite having licenses for 15-20 hectares. Why? Because they have no guaranteed buyers. Without guaranteed offtake, farmers won’t invest in scaling. Without scaling farms, processors can’t justify building biorefineries. Without processing infrastructure, food companies can’t embed seaweed into supply chains. Without demand signals, investors won’t deploy capital. Everyone is rational in their individual decision. And collectively, we’re paralysed.
The (approximate) economics tell the story:
At 0.5 hectares: £1,500 per tonne production cost (loss-making)
At 50 hectares: £750 per tonne (breakeven + profit)
Unit costs halve when you double farm size
We have the licensed marine space. We have the technology. We have the markets. What we lack is simultaneous action across multiple value chain segments.
What Horizon Seaweed’s candid assessment revealed
Back in 2024, Horizon Seaweed published a retrospective on their eight years of farming trials (2016-2023). Their frank account of challenges, detailing biofouling, harvest timing bottlenecks, processing yield losses, and the brutal reality of moving tonnes of wet biomass, revealed why this industry hasn’t scaled naturally. Seaweed farming is hard. The science works. The economics work at scale. But the operational and logistical reality means small farms get crushed by unit economics.
Horizon’s decision to pause farming and focus on wild harvesting and processing is instructive: it’s not farming that’s the constraint; it’s the entire system. They succeeded in farming. They succeeded in processing. But without coordinated scale across both, profitability remained elusive.
The systemic solution needs blended finance
Here’s what emerged from yesterday’s discussions: we don’t need more research or pilots. We need coordinated capital deployment using blended finance.
The model works like this:
Public catalytic capital takes first-loss positions, provides guarantees, and funds technical assistance;
This de-risks the investment enough to attract private capital at a sensible leverage ratio; &,
The total capital pool can fund many investments across the value chain simultaneously: processor biorefinery companies, cooperative processing hubs, environmental applications, and offtake-driven partnerships with food and pharma companies.
When these investments are coordinated, rather than sequential, the catch-22 breaks: processors create demand → farmers can scale → supply aggregates → buyers commit → environmental credits add revenue → returns attract more investment. And yesterday’s most productive insight?: the valley of death isn’t crossed by isolated bets. It’s crossed by systemic investment.
The critical year(s) ahead
Back in 2023, Standard Chartered estimated a ‘now or never’ moment for UK seaweed. If Asia consolidated its position and established supply chains over the next 18 months, Europe missed the window. The threat still holds. If we deploy coordinated capital and secure offtake agreements now, UK farmers can scale into licensed areas within 2-3 years.
The ingredients are, at least partially, present:
Policy momentum (Marine Net Gain requirements, offshore wind integration);
Corporate interest (Cargill, Nestlé, Danone publicly committed);
Proven technology (multiple farming and processing models);
Funding mechanisms (National Wealth Fund mandate, blended finance expertise exists); &,
Urgent need (coastal communities, food security, climate targets).
What’s missing: collective will to act simultaneously across the ecosystem.
So what happens next?
Yesterday’s participants left with specific commitments:
Farmers committing to form aggregation structures
Processors planning offtake negotiations
Investors identifying target investments
Policymakers identifying regulatory streamlining opportunities
Buyers piloting trial partnerships
These aren’t vague aspirations. These are 90- to 180-day commitments with accountable owners and timelines.
We’ll reconvene next year to measure progress. Early movers who secure offtake agreements or investment will have gained enormous advantage. Late movers risk watching the industry scale without them.
The lesson for blue economy investors
Yesterday crystallised something broader for me: the blue economy is hitting its scaling phase. Nature-based solutions have moved from innovation theatre to commercial viability. But they’re all trapped in the same valley of death, too late-stage for venture capital, too early-stage for institutional investors.
Blended finance isn’t charity. It’s the unlocking mechanism for productive assets that generate reliable returns and environmental impact. Seaweed demonstrates this perfectly. But it requires patient capital, systems thinking, and willingness to coordinate across competitors.
The UK seaweed industry stands at an inflection point. This symposium was about recognising that moment and catalysing action. The ‘glimmers of light’ participants mentioned weren’t theoretical. They were commitments from real stakeholders ready to move.
Now we find out if we can sustain the momentum.
If you’re working in the seaweed industry, whether farming, processing, biorefining, academia or policy, and are interested in being part of the coordinated action happening over the next 18 months, reach out. The valley is narrowing, but the window is still open.