EnergyPathways (AIM: EPP) taps Siemens for multi-day CAES tech—can MESH reshape UK storage?

EnergyPathways plc (AIM: EPP) has signed a cooperation agreement with Siemens Energy Global GmbH & Co. KG, marking a major step forward in the development of modular long-duration energy storage systems. The agreement targets a fusion of Compressed Air Energy Storage (CAES) with hydrogen-compatible gas turbines, designed to absorb and discharge multi-day energy from surplus renewable power.

This non-binding framework, announced on November 19, 2025, establishes a global development roadmap with a spotlight on the United Kingdom’s East Irish Sea. The flagship MESH project will serve as the first testbed for the integrated CAES system, aiming to deploy the technology at commercial scale by 2030. The collaboration underscores growing urgency in the UK and globally to commercialize long-duration energy storage (LDES) systems capable of mitigating wind power curtailment and balancing intermittent grids.

EnergyPathways will contribute its proprietary geo-storage expertise, salt cavern access, methane pyrolysis licensing, and project-level execution, while Siemens Energy will provide the engineering muscle and systems integration capabilities. Siemens Energy generated €39.1 billion in revenue in fiscal 2025 and operates in more than 90 countries, offering technical de-risking support that many investors had hoped EnergyPathways would secure ahead of MESH’s development phase.

How will the partnership help absorb wasted wind power at scale?

The rise of renewable energy in the United Kingdom has led to billions of pounds worth of clean power being curtailed every year, particularly from offshore wind farms. Grid bottlenecks, insufficient storage, and a lack of flexible generation have all contributed to this underutilisation. The EnergyPathways–Siemens Energy agreement directly targets this structural inefficiency.

The proposed CAES system will store curtailed power as compressed air in salt caverns located beneath the seabed. During low renewable generation periods, this stored air will be expanded and used to drive turbines, supplemented by hydrogen combustion and thermal systems, to provide flexible, dispatchable power back to the grid. By integrating CAES with hydrogen-compatible gas turbines, the platform is being designed for modularity, cost-efficiency, and multi-day operation.

The collaboration represents one of the first serious attempts in the UK to couple long-duration compressed air storage with clean hydrogen production and usage, allowing a closed-loop decarbonised energy system. Unlike conventional battery systems, which are typically constrained to four to six hours of output, CAES platforms offer multi-day flexibility, making them a better fit for managing seasonal variability and grid-wide storage needs.

Why is the MESH project central to this collaboration?

EnergyPathways’ Modular Energy Storage Hub (MESH) is a large-scale decarbonisation and energy security facility that integrates multiple technologies within one salt cavern-based system. The facility will feature long-duration energy storage, hydrogen production via methane pyrolysis, flexible low-carbon electricity generation, and synthetic graphite production as a by-product.

The MESH concept leverages existing offshore infrastructure and nearby wind resources in the East Irish Sea to create a dispatchable, low-emissions energy hub. The compressed air, hydrogen, and thermal storage units will work in tandem to balance supply and demand, reduce reliance on fossil peaker plants, and enhance grid reliability.

What sets MESH apart is its multi-stream monetisation model. In addition to selling power to the UK grid, the facility plans to produce low-carbon hydrogen, which could feed into the government-backed Project Union hydrogen pipeline. The methane pyrolysis process, for which EnergyPathways holds exclusive UK rights, will generate clean hydrogen and high-purity synthetic graphite, the latter of which has applications in EV batteries, electronics, and other energy storage components.

Investors tracking the space believe that this layered output model strengthens the project’s commercial viability, offering diversified revenue streams that can be attractive to infrastructure and energy transition funds.

What makes Siemens Energy a strategic fit for the project?

Siemens Energy’s involvement brings global credibility, engineering depth, and a rich portfolio of integrated energy systems. The German industrial group is one of the few players globally with end-to-end solutions spanning gas turbines, electrolyzers, grid infrastructure, and thermal systems.

By aligning with Siemens Energy, EnergyPathways can fast-track design validation, navigate regulatory standards more efficiently, and potentially access export markets where Siemens Energy already has installed infrastructure or government-backed partnerships. The taskforce model laid out in the agreement will allow both firms to co-develop modular designs that can be replicated beyond the UK once the MESH pilot is operational.

In the view of analysts covering the energy transition sector, this partnership could open the door for EnergyPathways to position MESH not just as a domestic clean power asset, but as a blueprint for global markets looking for LDES solutions that go beyond lithium-ion batteries or pumped hydro.

What does the current stock performance say about investor sentiment?

As of November 19, 2025, shares of EnergyPathways plc (AIM: EPP) were trading at 5.30 GBX, reflecting a 2.91 percent gain from the previous session. The day’s trading saw an open of 5.60 GBX and a bid/offer spread of 5.20/5.40 GBX.

EnergyPathways’ one-year price chart shows a volatile journey, with a steep decline in mid-2025 followed by a sudden rally in early October, widely attributed to renewed interest in the MESH project and anticipation of strategic partnerships. From trading below 3 GBX in August, the stock surged past 8 GBX before stabilising in the mid-5 GBX range.

The announcement of the Siemens Energy agreement appears to have offered a mild boost in market confidence, especially among small-cap energy transition investors seeking high-upside infrastructure plays. Although the agreement remains non-binding for now, it is perceived as a step toward risk-sharing and project acceleration.

Institutional appetite has yet to fully materialise, but sentiment is improving as the company moves from concept phase into system design, engineering validation, and project-specific execution. Traders and institutional analysts alike will be monitoring whether EnergyPathways can convert this framework into a binding development and commercial agreement in the coming quarters.

What’s next for the MESH project as 2030 targets approach?

EnergyPathways has set a target for MESH to be operational by 2030, a timeline aligned with the UK Government’s Clean Power ambitions. To meet this goal, the company will need to complete several key steps, including engineering feasibility, permitting, environmental approvals, and project financing.

The next six to twelve months are expected to be critical for de-risking the MESH platform. Stakeholders will be watching for front-end engineering design (FEED) milestones, technology integration proofs with Siemens Energy, and potential policy support such as Contracts for Difference (CfD) eligibility or LDES-focused government funding schemes.

The timing also aligns with broader market trends. As national grids like the UK, Germany, and California face growing challenges in balancing intermittent wind and solar, demand for scalable, affordable LDES is rising. Analysts believe that MESH could be among the earliest commercially viable CAES–hydrogen hybrid systems in Europe, if timelines are maintained.

Commercial offtake deals, grid interconnection approvals, and validation of EnergyPathways’ methane pyrolysis hydrogen pathway will also be in focus as institutional investors weigh long-term capital commitments.

What are the key takeaways from the EnergyPathways and Siemens Energy CAES partnership?

• EnergyPathways plc (AIM: EPP) has entered a non-binding cooperation agreement with Siemens Energy Global GmbH & Co. KG to co-develop a modular Compressed Air Energy Storage (CAES) system integrated with hydrogen-compatible power generation.

• The agreement is focused on designing a multi-day long-duration energy storage (LDES) solution capable of repurposing excess offshore wind and other curtailed renewable power.

• The partnership will begin with EnergyPathways’ flagship MESH project in the East Irish Sea and Cumbria, a scalable clean energy hub combining compressed air, thermal, and hydrogen energy systems.

• The MESH facility will also incorporate methane pyrolysis hydrogen production and generate synthetic graphite as a by-product, enhancing the project’s decarbonisation and monetisation potential.

• Siemens Energy brings global-scale engineering and energy system expertise, while EnergyPathways contributes UK-based salt cavern storage access, proprietary LDES IP, and project execution capacity.

• The MESH system is designed to address UK grid stability challenges and contribute to the government’s 2030 Clean Power goals through a flexible, multi-vector energy storage and supply model.

• EnergyPathways shares (AIM: EPP) rose 2.91 percent to 5.30 GBX following the announcement, with analysts cautiously optimistic about institutional interest pending firm contractual milestones.

• The cooperation is currently non-binding but sets the stage for formal project agreements, engineering development, and funding opportunities over the next 12 to 18 months.

• The collaboration positions EnergyPathways as a potential early mover in multi-day CAES plus hydrogen platforms—a sector gaining traction amid rising renewable curtailment and decarbonisation pressure.

• Investors and policymakers will be closely monitoring FEED progress, regulatory clearances, Siemens Energy’s long-term involvement, and how EnergyPathways converts this partnership into a bankable energy infrastructure asset.