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Energy storage technologies are attracting attention, but this is generally reserved for batteries and their limitations, mostly during discussions about range anxiety relating to electric vehicles.

By: David James 

Even though relatively few people are talking about it, Long-Duration Energy Storage (LDES) is arguably the most significant technology to monitor in the new power play. Short-duration storage is measured in minutes, 240 at the most. Medium-duration  storage runs from four to 12 hours and LDES covers everything beyond that. It can stretch to weeks, months or even quarters. The tech has become a hotbed of investment and innovation of late.

What factors are behind this upsurge in R&D activity?

First and foremost, LDES is seen as vital to energy security and market stability, helping the electricity grid to manage peaks and troughs in supply and demand. It minimises the risk of brownouts, unexpected drops in voltage, and blackouts. Given the  proliferation of extreme weather events such as winter storms, such resilience is becoming ever more important. LDES is also vital for high-volume power users such as heavy industry, as well as for consumers in remote areas where grid connectivity and  supply can be limited. In effect, it provides them with a safety net. But the climate emergency means that LDES is more than an insurance policy against shocks to the system. It’s become key to the energy transition. Decarbonising the electricity supply is  crucial to achieving net zero, especially with the electrification of transport and heat fuelling global demand for green power.

Harnessing the full potential of renewable energy sources such as the Sun and Wind requires their variable and intermittent output to be optimised over time. As a result, storage is booming. Growth in the global market broke records last year, capacity was up 68% on the previous year and forecasts that it will grow 15-fold by the end of the decade. But the demand for long-term  storage is growing at an even faster rate. The Long Term Duration Storage Council, an industry body comprising more than 60 members in 19 countries, has forecast that the world’s electricity grids will need to deploy 85TWh to 140TWh of LDES by 2040. This growth trajectory places the market’s potential value by that year somewhere between £1.2tn and £3.2tn. Potential scenarios explored by National Grid suggest that the UK will require at least 50GW of LDES capacity by 2050, in line with the nation’s  net-zero aims.

“Decarbonising the electricity supply is crucial to achieving net zero, especially with the electrification of transport and heat fuelling global demand for green power.”

To put that number in perspective, there is about 5.3GW of LDES operational in Great Britain today. This comprises roughly 2.8GW of pumped hydro and 2.5GW of newer Lithiumion battery storage. In short, there’s a lot of work to be done. But the industry is working hard on the task at hand. As evidenced by the range of projects approved for some of the £69m funding awarded last year under the government’s Longer Duration Energy Storage Demonstration (Lodes) competition, the possible  solutions take many forms. The Lodes portfolio contains all of the core technologies with a genuine prospect of working on a commercial scale.

These include compressed-air energy storage (CAES), liquid-air energy storage (LAES), thermal energy storage,  flow batteries and pumped hydropower; plus power-to-low-carbon gases, developed in conjunction with the production of green hydrogen. The materials in the mix range from metal hydrides to 3D-printed concrete. Some of the more exotic-sounding solutions involve the lifting and lowering of weights in a vertical underground shaft, the use of salt caverns as a hydrogen store and the creation of a 30MWh vanadium flow battery that’s set to be one of the largest of its kind in the world. The real  growth opportunity for LDES lies in the property sector, so tapping into the residential market makes sense. At present, there are really only two operational forms: the solar store and the home surplus storage system.

But neither is scalable in terms of  both space and cost for most people. Some projects have already made it through the demo phase. For instance, the Earba Storage project, which will use two lochs in the Scottish Highlands, is set to provide significant amounts of both power (up to 1.5GW) and stored energy (up to 33GWh), making it the largest pumped-hydro scheme in the UK. While progress is being achieved, If the government cannot afford to explore every avenue at this stage, it should open doors for the private sector, whether  that’s through innovation funds, tax incentives or supporting investor relations.