Insight and inspiration

GridReserve®: the future of energy storage

At MoltexFLEX, our mission is to bring low-cost, carbon-free energy to the world. And of course, our focus is our ground-breaking FLEX advanced nuclear reactor.  

But MoltexFLEX is more than just a nuclear reactor developer – a vital part of our offering is the GridReserve® thermal energy storage system, which gives the FLEX reactor the flexibility to rapidly respond to grid demand.

So, let’s take a closer look at GridReserve® and how it could hugely benefit electricity production around the globe.

Firstly, how does GridReserve® work? The system consists of a group of insulated tanks filled with a molten salt mixture that stores thermal energy produced by the FLEX reactor, and is similar in approach to that used to store thermal energy in concentrated solar power plants. The mixture is made up of sodium, potassium, and magnesium chlorides.

The tanks store heat for several days at temperatures of about 700°C. This stored heat can then be used to create steam to run conventional generation turbines, enabling the system to load-follow – filling peaks in demand, or dips in production from other sources.

The GridReserve® system stores heat in tanks of molten salt, allowing the energy to be used to cover peaks in demand.

Whereas some small modular reactor designs aim to increase or reduce their power output to provide flexible electricity, which the FLEX reactor can also do, GridReserve® allows the FLEX reactor to continue running at full power while putting several times more power onto the grid for shorter durations. This enables the combined FLEX and GridReserve® system to easily cover peaks in demand – a role currently filled by CO2-producing fossil fuels, typically gas-fired power plants.

Installed capacity costs are projected to be as low as those of a gas-fired power plant. Used with the FLEX reactor, the levelised cost of thermal storage with GridReserve® will be approximately £10/MWh, which translates to a levelized cost of electrical storage of roughly £50/MWh. This is much more cost-effective than many other proposed energy storage systems currently in development. GridReserve® fills a gap for large scale, low-cost storage.

GridReserve® will be significantly more cost-effective than other forms of energy storage.  

However, there may be an opportunity for GridReserve® to make a big difference to the electricity generation landscape – and the race to Net Zero – even before the FLEX reactor is ready for deployment.

MoltexFLEX has years of experience and has invested heavily in corrosion control, chemistry and metallurgy research. This is an area where others have struggled when considering molten salt energy storage. It would therefore be entirely possible to use this expertise to bring GridReserve® into operation before the FLEX reactor.

While the optimum source of heat for GridReserve® is of course the high-temperature output of a nuclear reactor such as the FLEX reactor, it would also be possible to store energy in the form of renewable-generated electricity. It is already clear that failure to de-couple generation from demand is hindering our ability globally to extract maximum value from low-carbon sources, as seen in examples like wind farms being paid to shut down when supply outstrips demand, or grid capacity limits on solar projects.

Implementing a low-cost, reliable, large-scale, long-duration energy storage system like GridReserve® could be transformational for low-carbon energy producers. Moreover, this system can be deployed anywhere, at any time, without complex infrastructure – making it the ideal partner to a range of developments. 

An increased focus on GridReserve® would not come at the expense of the FLEX reactor – our nuclear technology will always remain our primary goal. But in the face of ever more serious predictions about the effects of climate change, it would be wrong to leave GridReserve® ‘on the shelf’ until the FLEX reactor is ready. Instead, if its development were to be accelerated, GridReserve® could contribute to the energy transition in the nearer term.

In fact, if we were to boost the development of GridReserve®, it would also support the development of the FLEX too. MoltexFLEX now has massive skill in handling molten salt and in controlling corrosion for extended periods – by demonstrating this capability with GridReserve®, it would provide governments and investors alike with early demonstration of a key component of the technology solution, and provides very valuable operating experience of molten salts to support the licensing of the FLEX technology. Plus, the revenue from rolling out GridReserve® could be ploughed back into development of the FLEX reactor.

At the moment, MoltexFLEX is only considering the possibility of fast-tracking the development of GridReserve®, and not making a cast-iron decision on the future path of the business. Nevertheless, informal discussions with potential stakeholders around the globe have already revealed that many are interested in such an approach as they can see the considerable benefits that GridReserve® could bring to their power grids.

Few small modular reactor developers are proposing a suite of technologies in the same way that MoltexFLEX is – namely, to provide a solution for flexible energy generation and storage for zero-carbon heat and electricity generation. It’s just another example of the flexibility that gives us our name – which will make MoltexFLEX and GridReserve® key players in winning the fight against climate change.

David Landon, CEO, MoltexFLEX

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