A grid overwhelmed by its own success
The UK’s green revolution has been so successful that we now produce more electricity than we can use when the wind is up. On blustery days, turbines are ready to flood the grid with clean power. The problem is time. Demand peaks when the air stills and darkness falls, not when the gusts arrive across the North Sea.
Here is the challenge in plain terms. We cannot store that surplus in any meaningful way and bring it back hours or days later when it matters most. The physics of wind are indifferent to the rhythms of a nation making dinner, charging cars and boiling kettles at six in the evening. A system built for a steady fossil supply struggles to catch the peaks and carry them through the troughs.
There is a cost to that mismatch. Because of the way the market is structured, generators are paid to switch off on windy days. Curtailment has become a line item of national life. The total is roughly £2.7 billion a year at present. That is money for electricity not produced. It also shows up on household bills. Call it £90 to £100 each year per home. Without resolution, the figure could climb to as much as £8 billion by 2030, which would be about £280 on the average bill for power you never see.
The fragility of Britain’s gas buffer
The second vulnerability is Britain’s limited gas storage. Think seven to ten days of cover, and half of that cushion sits in a single asset, Centrica’s Rough facility. Rough has been life support as North Sea production fades and gas backup power is needed in winter spikes when no wind is available. Without a long-term deal between Centrica and the UK Government, the facility could close. Imagine a sharp, cold snap with no wind, and the calculus becomes difficult. The UK would be bidding in global markets for cargoes of LNG that may not be there at any price. France and Germany treat storage as a strategic asset and their reserves are measured in months, not days.
A proposal built around time
EnergyPathways PLC (AIM:EPP) enters this story with a proposition that takes those awkward facts seriously. If time is the problem, build time into the system. The company’s Marram Energy Storage Hub (MESH for short) in North West England is designed to capture wasted wind, hold it for days and release it as firm power on demand. It has been designated a development of national significance by the Secretary of State for Energy Security & Net Zero, which matters because planning is often the invisible brake on energy projects. Target start-up is 2030, subject to financing, planning and permits.
"We stand on the cusp of replacing that vulnerability with strategic strength and in doing so securing our energy future,” says Ben Clube, CEO of EnergyPathways. "In short: this is the right idea at the right time and it already has political tailwinds"
Tackling the transmission pinch points
Location is strategy. Much of Britain’s wind sits in Scotland and the North, while demand clusters further south. Two well-known constraint boundaries on the transmission network, B6 and B7a, limit how much power can flow south on windy days. When those boundaries pinch, the grid pays to turn off turbines in the North and runs gas-fired power plants closer to London and the South East where demand is highest. EnergyPathways proposes to park a long-duration energy store on the northern side of that bottleneck, soak up the excess and send it back when the country needs it. The site has multiple grid access points and sits within reach of a large concentration of operating and planned offshore wind farms in the Irish Sea.
"It turns a national infrastructure bottleneck into a competitive advantage," says Clube.
Multi-day storage at industrial scale
At the heart of the plan is long-duration energy storage measured in days rather than minutes. On windy days, cheap or curtailed power drives compressors that push air into salt caverns while capturing heat that would otherwise be lost. When the system is tight, the stored air expands through a turbine to generate electricity, with the stored heat improving efficiency. The initial build targets 350 megawatts of dispatchable capacity and about 57 gigawatt hours of energy, enough for more than seven days of continuous supply at full output. Ramp from cold start is five to ten minutes, which puts MESH in the fast response category that the grid prizes.
Costs are where the concept sharpens.
EnergyPathways estimates a ‘levelised’ cost of its flexible power could be up to a third less than the typical ranges for alternatives. The cost of maintaining separate backup power systems, such as new combined cycle gas generation plants with carbon capture, unabated gas reciprocating engines and other flexible gas options, will be a costly affair once fuel and carbon are included on current assumptions. The point is not that gas disappears. Is it that a multi-day store fed by cheap wind can compete with the marginal plant that currently keeps the lights on today? "Clean firm power, economically competitive with fossil flexibility that is the convergence investors, consumers and policymakers have been waiting for," says Clube.
Geology, cost and longevity
Capital cost matters just as much as the £ per megawatt hour headline. Long-duration energy storage can be prohibitive in some forms and impossible to finance in others without support. Here, the geology helps. Thick salt sequences (layers/strata) under the Irish Sea allow large caverns to be created at comparatively low unit cost. On EnergyPathways’ figures, storage capacity capex comes out near £11,000 per megawatt hour of capacity for MESH. By contrast, today’s grid battery fleet sits around £430,000 per megawatt hour on average for storage capacity, while pumped hydro typically ranges from about £70,000 to £300,000 per megawatt hour depending on the site. Asset life is modelled at more than 25 years for the MESH store, less than 15 years for many batteries and 50 years or more for pumped hydro. The message is that MESH aims for a hydro-scale duration with battery-like responsiveness, while undercutting both on unit storage cost.
The industrial backbone
Partnerships and industrial pedigree are central to the pitch. Siemens Energy is the core technology partner for compressed air and heat storage, hybrid hydrogen power plant and gas turbine systems that anchor the dispatchable block. Wood Group leads front-end engineering and design, with Costain and Zenith involved on civils and storage infrastructure.
EnergyPathways plans to lead on the hydrogen side to help decarbonise the UK’s energy system. It has exclusive rights to use KBR Inc. and Hazer Group's globally licensed methane pyrolysis technology to produce hydrogen within the UK, with Mitsui supporting commercial scale-up. This is not a science project assembled from lab prototypes. It is a system built from known machines and processes, integrated in a way that meets the specific constraints of the UK grid.
Hydrogen as the second revenue pillar
Hydrogen adds a second economic pillar that improves the power metrics. Rather than rely entirely on electrolysis at today’s prices, the company plans to produce low-carbon hydrogen on site using methane pyrolysis, which will be at a fraction of the cost of green hydrogen. In that process, natural gas splits into hydrogen and solid carbon. Instead of producing carbon dioxide that must be captured and stored, you get high-quality graphite that can be sold into industrial markets (for example, for use in EV batteries). On EnergyPathways’ assumptions, hydrogen lands at about £3 per kilogram or roughly £75 per megawatt hour on a higher heating value basis. If you credit the graphite by-product at a conservative price, the effective cost falls to the equivalent of about £46 per megawatt hour. The initial train is 20,000 tonnes per year at around 90 megawatts. "Clean Hydrogen, with revenue-generating byproduct, a commercially viable business not dependent on subsidy,” says Clube.
Ammonia as a seasonal outlet
With KBR Inc’s hydrogen technology, ammonia provides a straightforward bolt-on market outlet for hydrogen production. Britain currently imports ammonia for fertilisers and chemicals, exposing industry to volatile prices and potential carbon border costs in the coming years. EnergyPathways proposes a domestic plant of roughly 110,000 tonnes a year, fed by the low-carbon hydrogen stream, located onshore at Barrow-in-Furness in Cumbria. With carbon border adjustments likely to raise the delivered cost of high-emission imports, the project’s indicative levelised cost in the mid three hundreds of dollars per tonne becomes competitive. It also gives the hydrogen system seasonal flexibility. If power demand does not absorb all output in a windy spring, ammonia synthesis provides an alternative sink that supports the economics of the whole hub.
Gas security built into the model
Security sits underneath the spreadsheets. The project includes gas storage of around 17 terawatt hours, which can be developed without needing Government subsidy. The plan is to produce indigenous gas from the Marram gas field reservoirs to storage, with onshore compression and connections into the National Transmission System at Barrow. In a country that could be about 80% dependent on imported gas by 2030 and that would have only a handful of days of cover if Rough shut, adding a Rough-sized store in the North West is not just a commercial proposal; it is an insurance policy.
The alternatives and the trade-offs
Set the project against the main alternatives and the trade-offs are clear. Batteries are superb for frequency response and short-duration balancing, but the typical grid-scale installation delivers only a couple of hours of energy. That is perfect for smoothing a lunchtime wobble and poor at carrying energy through a weather system. Pumped storage hydro is proven and long-lived, but site-constrained and capital-intensive. New gas with carbon capture can deliver firm power, but it relies on CO₂ transport and storage networks that are still being built and on fuel whose price Britain does not control. EnergyPathways’ claim is that MESH offers multi-day duration at a unit storage cost that undercuts the competition, with a services stack broad enough to finance a multi-decade life, and with an emissions profile that trends down as hydrogen ramps.
The risks and the policy gap
None of this is automatic. Integration projects can suffer from the curse of interfaces, where perfectly decent components do not play nicely together. Environmental questions must be answered with rigour, from brine disposal to coastal works. Development budgets must bridge the gap to a final investment decision. Most of all, policy must recognise system value. Long-duration storage saves money that is otherwise spread thinly across the grid. It reduces curtailment, avoids some network upgrades, displaces gas in the wrong places and dampens price volatility. Those savings do not accrue to a single buyer. They accrue to households. If Britain wants infrastructure that solves a system problem, markets will need to pay for the solution.
A question of readiness
Yet a decade into the renewables surge, it is also risky to waste what we build. Curtailment is not a rounding error. Households are already paying for electricity that never reaches the socket. Gas storage remains shallow and relies on one asset that may not always be there. Our neighbours stockpile energy like it is strategic because it is.
EnergyPathways offers one attempt to change the terms of trade. Catch the wind when it blows. Hold it underground and in molecules. Send it back when the industry needs it, and when people cook their tea and put their children to bed. Add a week of gas cover when a cold blast settles in. Tie it together with partners who build things for a living, from Siemens Energy to Wood, Costain, KBR, Hazer and Mitsui.
If we want a clean energy system that works on ordinary days and on the worst days, we need places that can turn a gusty Saturday into a steady Tuesday. We need stores that pull risk out of winter. We need projects that stitch together power, gas and hydrogen into something more than the sum of their parts. The wind is already here. The question now is whether we are ready to hold it.