- Caudal Energy, an Oxford University spinout formerly known as Porpoise Power, has raised £4.3M led by Oxford Science Enterprises and Empirical Ventures to test a fin-based tidal generator that operates in mid-flow sites conventional turbines cannot reach.
- The raise brings total funding to £5.5M and funds full-scale testing at Strangford Lough, Northern Ireland, ahead of a first commercial deployment targeted for 2028.
- The tidal energy market stands at $1.4B in 2025 and is forecast to reach $3.66B by 2030 at a 21.1% CAGR, according to The Business Research Company.
Tidal energy has one advantage no other renewable can match: it is completely predictable. The tides run on lunar cycles, not weather systems. Every grid operator in the world knows exactly how much tidal power will be available at any given hour, decades in advance. And yet tidal energy remains a rounding error in the global renewables mix, because the technology built to harness it has always been too complex, too expensive, and too site-specific to deploy at scale.
Caudal Energy, the Oxford-headquartered spinout founded in 2024 and formerly known as Porpoise Power, is trying to change that. The company has raised £4.3M in a round co-led by Oxford Science Enterprises (OSE) and Empirical Ventures, with participation from returning investors Zero Carbon Capital and Creator Fund, and new backers Kibo Invest and Oxford Innovation Finance. Total funding now stands at £5.5M, following a £1.2M pre-seed in 2024 led by Zero Carbon Capital.
The company was co-founded by Hilary Struthers, CCO and former Shell commercial energy executive with 20 years of experience in commercial energy strategy and sustainability, alongside Professor Adrian Thomas, whose breakthrough hydrodynamic research at the University of Oxford forms the scientific foundation of the technology, marine systems engineer Martin Hall, and CEO John Kennedy, previously MD at Wayfair and CEO at MOO.
The problem and what Caudal built to solve it
Conventional tidal turbines need peak flows above 5 knots to operate economically, restricting viable deployment to a handful of extreme tidal sites globally. Caudal’s modular, surface-mounted fin-based system, inspired by the efficiency of the caudal fins of marine mammals, operates in mid-flow tidal locations where peak flows exceed 3 knots, dramatically expanding the number of sites where tidal energy can be deployed commercially. The simpler architecture also reduces installation costs and ongoing maintenance complexity compared to deep-water turbine systems.
Caudal currently sits at Technology Readiness Level 5. The £4.3M funds full-scale testing at Strangford Lough in Northern Ireland, with first commercial deployment targeted for 2028 at TRL8.
CEO John Kennedy said: “The future energy system needs renewable power that is not only clean, but dependable and built to scale. We founded Caudal to challenge the assumption that tidal energy has to remain complex, costly and niche. By unlocking the potential of mid-flow tidal sites, we believe Caudal can dramatically expand where tidal energy can be deployed and how commercially competitive it can become.”
Struthers brings something the technology alone cannot: two decades of Shell commercial relationships and a current NED seat at renewables developer Low Carbon, giving Caudal a direct line into the utility and industrial procurement conversations that most early-stage energy hardware companies spend years trying to access.
The investors
OSE, the University of Oxford’s affiliated venture builder with over £2.5B committed from more than 300 investors, recorded two landmark exits in 2025: Oxford Ionics, acquired by IonQ for $1.08B in June, and OrganOx, acquired by Terumo Corporation for $1.5B in August, the largest acquisition of any UK university spinout to date.
Andy Straiton, Investment Lead at OSE, said: “Caudal Energy is addressing one of the most important challenges in the transition to renewable energy: how to provide predictable, scalable generation that complements intermittent power sources such as wind and solar. Importantly, Caudal’s approach is designed around the economics required for large-scale deployment, not just technical performance.”
Johnathan Matlock, General Partner at Empirical Ventures, added: “Grid operators are increasingly pricing predictability into the system, and the renewables that benefit are the ones that can deliver deterministic output without storage costs. Caudal is one of the only tidal platforms we have assessed with a credible path to LCOE parity with offshore wind, and the team has done the detailed engineering work to back up the modular deployment claim at scale.”
The competitive landscape
Caudal enters a market where most competitors have struggled to cross the commercial viability gap. Orbital Marine Power, the Scottish turbine developer that raised $9.33M in December 2025, operates floating platforms with underwater rotors requiring high-flow conditions and deep-water infrastructure, the precise constraints Caudal’s architecture avoids. Minesto, the Swedish listed company with a market cap of $22.2M, uses an underwater kite system targeting lower-velocity sites but remains pre-commercial. Nova Innovation, deploying fixed-bed turbine arrays in Orkney as part of a Horizon Europe consortium, focuses on established high-flow sites. None of the three uses an oscillating foil architecture at Caudal’s target cost and site profile.
The tidal energy market stands at $1.4B in 2025 and is forecast to reach$3.66B by 2030 at a 21.1% CAGR, according to The Business Research Company. Europe holds the largest regional share, theEU’s 2020 Offshore Renewable Energy Strategy sets a target of at least 1GW of installed ocean energy capacity by 2030, with the UK running parallel investment programmes in tidal specifically.
For context on the broaderUK cleantech funding landscape, TFN tracked over £400M raised across green tech in 2025, with energy storage and predictable generation among the most active categories. The unanswered question for Caudal and for the tidal sector broadly is whether a £4.3M raise and a 2028 commercial deployment target is fast enough to secure a place in a renewables market that is already consolidating around offshore wind and utility-scale solar — and before the next wave of grid-scale battery storage removes the premium that grid operators currently pay for predictable baseload power. It is a race Caudal cannot afford to lose slowly.Other Oxford spinouts have shown the university’s deep tech pipeline can reach commercial scale — the question is whether the tidal window stays open long enough.
