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Tree Composites’ Path to Cheaper Offshore Wind

Global energy demand is surging, and the race to build renewable infrastructure at unprecedented scale has never been more urgent. But some of the most interesting innovations happen out of sight: in the joints and connections that hold everything together.

That’s also where new materials companies have a role to play — and Tree Composites, the TU Delft spinoff that won JEC Startup Booster 2025’s Product & Materials Award, is one such startup. Since then, this Dutch company has been making progress towards making offshore wind farms less expensive to build, COO Eline Spek told Sesamers.

Here’s what she had to say about Tree Composites’ technology, the team’s progress since winning, and what’s next for the tree-inspired company that is now aiming to accelerate the energy transition.

Sesamers: How would you briefly describe what your technology does?

Eline Spek: Tree Composites aims to accelerate the energy transition with innovative composite joints. Our wrapped composite joint replaces welded nodes in steel constructions — for example, jacket foundations for offshore wind. By wrapping steel tubulars with glass fibers and resin, we create joints that are stronger and far more fatigue-resistant than welds. This innovation reduces steel use by 40–60%, lowers CO₂ emissions by up to 50%, and doubles production efficiency, while enabling offshore foundations to last well beyond the typical 25-year design life.

Sesamers: Can you share a concrete example of how it can be used?

ES: Our joints are used in jacket foundations for offshore wind turbines. These jackets are currently welded together, a labor-intensive process that weakens the steel and drives up costs. By replacing those welded nodes with wrapped composite joints, we make it possible to manufacture jackets faster, with less steel, and with much longer service lifetimes. This allows offshore wind farms to be built at scale in deeper waters, reducing costs for developers and helping the industry meet growing global energy demand.

Sesamers: How did winning the JEC Startup Booster change your business?

ES: Winning the Startup Booster gave us even more international visibility and opened valuable conversations with investors. Just as important, the recognition and credibility from across the composites supply chain proved to be a real vote of confidence when speaking with launching customers in offshore wind. It also showed the wider market that we are ready to scale together with our supply chain.

Sesamers: What are the most significant milestones you’ve hit since winning? Any surprises?

ES: We built all of the composite joints needed for our first jacket foundation. Together with our partners, we are now constructing this jacket at a yard in the Netherlands. The design uses 50% less steel than a conventional foundation, and it is incredibly rewarding to see it come to life after years of development and testing.

Sesamers: What’s your top priority for 2026?

ES: Our top priorities are scaling up our production capacity and forming a consortium of partners to realize the first offshore jacket foundation with composite joints.

Note: This article is part of a commercial collaboration between JEC and Sesamers. Our team retained full editorial control over the questions and final content.

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Fundraising 43 minutes ago

London-based AI laboratory Ineffable Intelligence has emerged from stealth with a $1.1 billion seed round at a $5.1 billion post-money valuation, the company confirmed on 27 April 2026. The financing is the largest seed round ever raised by a European company and one of the largest first-money-in rounds in the global history of artificial intelligence. The round was co-led by Sequoia Capital and Lightspeed Venture Partners. Participating investors included Nvidia, DST Global, Index Ventures, Google, and the UK Sovereign AI Fund, the British government’s recently established vehicle for backing strategic AI capacity on home soil. A bet on a different path to general intelligence Ineffable Intelligence was founded in 2025 by David Silver, the former Vice President of Reinforcement Learning at Google DeepMind and the principal architect of AlphaGo, AlphaZero and AlphaStar. He is joined by three further DeepMind alumni: Wojciech Czarnecki, Lasse Espeholt and Junhyuk Oh. All four have spent the past decade at the frontier of reinforcement learning research, the discipline behind some of the most consequential demonstrations of machine learning over the past ten years. The company describes its objective as building a “superlearner” — an AI system capable of acquiring knowledge directly from its own experience rather than from human-generated text or imagery. “Our mission is to make first contact with superintelligence,” Silver said in a statement accompanying the launch. “We are creating a superlearner that discovers all knowledge from its own experience, from elementary motor skills through to profound intellectual breakthroughs.” The framing is a deliberate departure from the dominant industry trajectory. Most leading AI laboratories, including OpenAI, Anthropic and Google DeepMind itself, have built large language models trained primarily on the corpus of the internet, then refined that training with human feedback. Ineffable’s wager is that the marginal returns on scaling text-based pretraining are diminishing and that the next leap in capability will come from agents that learn endlessly from the consequences of their own actions, in much the same way AlphaZero learnt the game of Go without studying any human matches. Why $1.1 billion at seed The size of the round is unusual even by the inflated standards of the 2026 AI capital cycle. Two factors appear to explain it. First, frontier reinforcement learning at the scale Ineffable describes is computationally extraordinarily expensive: the company will need to operate vast simulation environments and train very large models against them, an undertaking that consumes capital at a rate closer to physical R&D than to traditional software. Second, the round signals a strategic move by Europe’s investor and policy ecosystems to retain the most ambitious AI researchers on the continent. The presence of the UK Sovereign AI Fund alongside Sequoia, Lightspeed and Nvidia is the clearest expression of that intent. The British government has publicly framed the investment as a bet on breakthrough AI that “can discover new knowledge”, positioning the country as a willing co-investor in domestic frontier laboratories. For Ineffable, the implication is access not only to capital but to compute, regulatory engagement and the still-resilient academic talent base around UCL, Oxford, Cambridge and Imperial. Founder pledge of historic scale Alongside the funding announcement, Silver disclosed that he is committing 100 per cent of any personal proceeds from his Ineffable equity to charity via the Founders Pledge network — described by the organisation as the largest pledge in its history. At the round’s $5.1 billion valuation, that commitment could ultimately exceed several billion dollars if the company succeeds. It is a meaningful gesture in a sector where the reputational stakes around concentrated AI wealth are escalating, and one likely to be referenced in subsequent founder-led commitments. Implications for the European AI landscape Ineffable’s emergence reshapes the European AI map in three concrete ways. It establishes London as the home of the continent’s largest-ever seed-stage company, complicating Paris’s recent narrative of frontier-AI primacy after Mistral’s earlier rounds. It validates a thesis — that reinforcement learning, not transformer scaling, is the next frontier — that has lately been losing capital share to language-model incumbents. And it confirms that the UK government is now willing to act as a balance-sheet co-investor in domestic AI laboratories, a posture much closer to the French model than to the predominantly grant-based regimes elsewhere in Europe. The execution risk is non-trivial. Reinforcement learning at frontier scale has historically required years of careful environment design before producing competitive systems, and Ineffable’s “first contact” framing sets a high bar against which it will be judged. But for now, with a billion dollars on the balance sheet, four of the discipline’s most accomplished researchers in the founding team and a sovereign co-investor at its back, Ineffable Intelligence is the most heavily resourced new entrant in the European AI cycle. Sesamers covers European fundraising rounds across deeptech, fintech and AI. Source: tech.eu.

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