AI-generated summary
For years, lithium-ion batteries have been the primary solution for energy storage, yet they face significant limitations including volatile raw material costs, geopolitical supply chain dependencies, and suitability mainly for short-duration energy storage. The challenge lies in maintaining grid stability during extended periods of low renewable energy generation, prompting the emergence of alternative long-duration storage technologies. Innovative approaches such as gravitational energy storage, heat storage, and liquid air storage are gaining traction as viable complements to lithium-ion batteries.
In Finland, the Scottish company Gravitricity is developing a gravity-based system that stores energy by lifting and releasing heavy weights in abandoned mines, while the US firm Energy Vault is combining gravitational storage with batteries to stabilize power grids and repurpose former coal mines. Heat storage is advancing through companies like Rondo Energy and Antora Energy, which use high-temperature refractory bricks and carbon blocks to store energy as heat that can be converted back to electricity or industrial heat on demand. Additionally, Highview Power in the UK is constructing the world’s largest liquid air energy storage facility, compressing and cooling air into liquid to be stored and later used for power generation.
The International Energy Agency predicts a 40% cost reduction in battery storage by 2030, but emphasizes the importance of diversification. Lithium batteries will excel in fast-response and mobility uses, while gravity, heat, and liquid air technologies will address longer-duration storage needs. Countries like Spain have unique opportunities to leverage existing industrial infrastructure and expertise to develop these alternatives. Together with advances in power electronics, these diverse technologies form an integrated energy storage ecosystem crucial for a clean, reliable, and sovereign energy future, supporting the global transition to Net Zero emissions.
Not only alternative materials such as magnesium, calcium, aluminum or zinc, there are systems that take advantage of natural forces and processes to store energy cleanly and efficiently.
For years, lithium-ion batteries have been touted as the almost unique answer to the challenge of energy storage. However, this technology has known limitations: volatile raw material costs, dependence on supply chains in certain countries and regions, and optimal performance only on minute or hour scales. The big question is how to ensure grid stability during days or even weeks of low renewable generation. And that is where alternatives come into play that, little by little, begin to become a reality.
In an abandoned Finnish mine, the Scottish company Gravitricity is experimenting with a system that is as simple as it is ingenious: lifting and releasing large weights to store and release electricity. This “giant elevator” harnesses gravity as a clean, long-lasting battery. The company has already built a demonstrator in Scotland and is collaborating with ABB, the multinational electrification and automation company, to accelerate projects in European mine shafts. Hundreds of kilometres away, in Switzerland and Italy, the US company Energy Vault is developing the “Miniera d’Energia” project in Sardinia: a hybrid solution of gravitational storage and batteries to stabilise the island’s grid and convert a coal mine into a technology hub.
Heat has also become a storage vector.
US-based Rondo Energy, backed by Breakthrough Energy Catalyst and the European Investment Bank, has launched its first “heat batteries” in Portugal and Germany: blocks of refractory bricks that accumulate energy at temperatures of more than 1,000 degrees. The company plans to deploy up to 2 GWh in industrial projects in the coming years. California-based rival Antora Energy, funded by BlackRock and Temasek, is betting on carbon blocks capable of storing heat for days, which can then be transformed into electricity or industrial heat on demand. Last year it closed a round of 150 million dollars to accelerate its commercial deployment.
The third path is opened by liquid air.
In Manchester, Highview Power is building the world’s largest cryogenic plant, with a capacity of 300 MWh. The principle is simple: compress and cools air into a liquid, store it in insulated tanks, and release it again to drive turbines when the grid requires it. The project has the support of the Bank of England and companies such as Centrica and Rio Tinto. Its aim is to demonstrate that long-duration storage is possible with relatively conventional infrastructures.
The International Energy Agency (IEA) estimates that the cost of battery storage for electricity will decrease by up to 40% by 2030, facilitating a faster transition to renewable sources versus fossil fuels. Beyond the final percentage,
Spain has an obvious opportunity in this area.
Engineering companies such as SENER have accumulated experience in thermal storage in solar thermal plants for more than a decade. In addition, the network of abandoned mines and the strength of the national ceramic and cement sector offer industrial capacities that could be reoriented towards heat or gravity storage projects.
Finally, Madrid-based Frenetic, part of the Bankinter Innovation Foundation’s portfolio, develops custom-made transformers and inductors for power electronics, thus improving the efficiency and integration of storage systems. This “invisible” innovation is decisive: without advanced electronics, technologies such as gravity, heat or liquid air would not be able to operate successfully on the grid.
The energy transition requires solutions that do not depend on a single material or a single geography. With creativity and
