MoltexFLEX Ltd – Written evidence (LES0027)


MoltexFLEX, Ltd. is a UK-based company, wholly owned by Moltex Energy Ltd, also based in the UK.


MoltexFLEX’s primary business is developing, demonstrating, and commercialising the FLEX nuclear reactor, a 60MWth/24MWe molten salt design, which will deliver electricity at less than £30/MWhe and process heat at less than £10/MWhr.


MoltexFLEX is pursuing an ambitious schedule to technically demonstrate the design around the turn of the decade, enabling scalable commercial rollout globally from the early 2030s.


In developing the FLEX reactor, MoltexFLEX recognised the importance of future nuclear systems being able to load-follow as effectively as gas plants, thereby offering a low-carbon solution to the need for dispatchable energy to accompany renewables and in doing so driving greater and deeper decarbonisation by enabling increased integration of renewables into the electricity mix and reducing the role of gas.


To address this need, MoltexFLEX developed its proprietary GridReserve® thermal energy storage system, which also employs molten salt, to accompany the FLEX reactor. GridReserve® enables grid-scale quantities of thermal energy generated by the reactor to be stored for hours or days at a time, with minimal efficiency losses, before being deployed for electricity generation or for process uses.


MoltexFLEX believes this demand-responsive generation capability is crucial for grid stability and enabling a net zero energy system, and seeks ongoing discussion with Government including but not limited to Great British Nuclear (GBN) on the use of FLEX reactors and the GridReserve® system to support a stable, net zero grid.


While the GridReserve® system is currently in the concept design stage, the basic system configuration is relatively straightforward, and MoltexFLEX has a well-established engineering development plan within its overall product development programme. The salt blend for GridReserve® has also been selected, following options appraisals and reviews of test data.


MoltexFLEX recognises the historical challenges of corrosion control, metallurgy and leak prevention associated with molten salt technologies, and is confident it has a market-leading USP, leaving the business well-positioned to secure a lead for the UK in the international market.


Moltex Energy, Ltd. was established a decade ago, and since then has conducted extensive scientific research and development aimed specifically at addressing these challenges. The portfolio of patents and proprietary data available to MoltexFLEX provides strong assurance that the fundamental challenges in molten salt management have been addressed, and that the business can now accelerate detailed system design and commercial engagement. This is a market leading position.


Looking forward, it is an emerging priority for MoltexFLEX to explore the potential for deploying GridReserve® more widely – and crucially more quickly – than the FLEX reactor, to make a more immediate and substantial contribution to decarbonisation. There are two primary ways in which this accelerated contribution to decarbonisation could be achieved:


  1. MoltexFLEX could license the use of GridReserve® to other technology developers and operators for partnership with thermal energy generation systems. From a technical perspective, this approach would be straightforward.
  2. Alternatively, MoltexFLEX could provide GridReserve® to developers and operators of renewable generation assets to create a way of storing energy generated before dispatching it to the grid. This would enable the UK to optimize its varied natural generating conditions independently of real-time demand, delivering this energy to the grid when needed.


The second of these solutions presents a notable opportunity for progress towards a net zero UK grid.


While the round-trip efficiency (RTE) for an electrical-thermal-electrical process would inherently be limited to c.40%; the low capital cost of molten salt thermal storage, along with the ability to harness abundant generation capacity from sources like wind and solar, means the economics of this approach are attractive – especially compared to an electricity-hydrogen-electricity approach proposed by some.


MoltexFLEX is also pursuing a wider programme of experimentation into novel methods of salt heating, which could significantly enhance the economics. Subject to the outcome of these ongoing experiments, MoltexFLEX intends to further engage potential clients to secure advanced Front End Engineering and Design (FEED) collaborations.



In response to the specific questions raised in the call for evidence:


3. Which technologies can scale up to play a major role in storage?


The MoltexFLEX GridReserve® thermal energy storage system offers a low-cost, high-capacity, long-duration and flexibly deployable solution for energy storage across various timeframes, capable of addressing both thermal and electrical storage challenges.


The GridReserve® system is relatively large and requires a standard fossil-fuel turbine alongside it. It is worth noting that many turbines and associated assets on decommissioned fossil fuel plant sites could be investigated for potential re-powering with GridReserve® units, unlocking systems infrastructure efficiencies. However, GridReserve® has relatively few restrictions or natural site requirements, making it widely deployable across diverse geographies in the UK.


GridReserve® technology is currently intended for commercial mobilisation in the early 2030s, alongside the FLEX nuclear plant. This schedule is governed by the regulatory and commercial timeframes associated with deploying a new nuclear technology – which are necessarily longer than for a pure storage plant. If there was sufficient market signal and Government enabling measures in place, MoltexFLEX believes GridReserve® could be commercially available within approximately three years.


In a balanced net zero energy system, GridReserve® could complement batteries for rapid response applications and other storage mechanisms where suitable. The system would also work well with hydrogen technologies, offering a potentially lower capital cost solution to energy storage. Indeed, the FLEX reactor is ideally suited to the production of green hydrogen.



4. What policy support is currently in place to support deployment of storage technologies? Is it sufficient to support deployment at scale?


In this context, MoltexFLEX, primarily a nuclear-focused business, is a relative newcomer to the storage sector and it must be recognised that there may be policy and enabling mechanisms of which the company is not yet fully aware.


That said, an initial view is that a clearer and more centralised means to engage with Government on storage technology solutions and understanding the available enablers would be beneficial for companies in this position.


As a UK-based business, MoltexFLEX seeks to develop an incredibly lucrative export product in GridReserve® and would benefit from better understanding what sort of low-level enablers might be available from Government, to help justify diverting limited internal resource from the company’s core projects (nuclear plant development) into the storage solution.


Such enablers could include access to a site to develop and demonstrate GridReserve®, FEED support grants, or a specific programme of engagement with global end-users to support companies developing storage products for export to the global energy sector.


Regarding the long-term market, it is vital for the energy sector, especially the electricity market, to be structured in a way that rewards dispatchable energy. The current market model, as understood, does not provide specific mechanisms to incentivise energy asset developers to ensure their plants are entirely dispatchable 24/7. The establishment of such a mechanism – through an asymmetric Contract for Difference (CfD), or amendments to the capacity market, for example – would place a far greater onus on energy project developers to incorporate storage provisions into their projects, and as such would strengthen the case for private financing in the development of energy storage products.



7. What steps should the Government take now to ensure this storage can come online later in the current decade?


If the UK Government wants to incentivise UK-based companies like MoltexFLEX to divert resources into accelerating the readiness of its storage products – and to facilitate raising private financing for storage products – the following measures should be explored:



MoltexFLEX appreciates the opportunity to respond to this consultation and would be delighted to offer oral evidence.


11 September 2023