Long-duration energy storage (LDES), often defined as storage for four hours or longer, will be essential as the world strives to meet ambitious net zero targets. The transition to renewable energy sources such as wind and solar, which are intermittent by nature, necessitates reliable energy storage to ensure a consistent and stable supply of clean power.

LDES systems will need to be deployed throughout the grid to store energy generated from renewable sources for extended periods.  

For example, the need for reliable, 24/7 renewable energy availability is increasingly critical as the deployment of artificial intelligence (AI) infrastructure accelerates. To support AI, power demands from data centres are forecast to increase by 50% by 2026. LDES will be vital to maintain these energy-intensive operations and power AI with renewable energy.

We will also need LDES systems to support the distributed grid infrastructure necessary for the wider adoption of electric vehicles (EVs). The mass rollout of EVs will necessitate a substantial overhaul of electricity transmission infrastructure to accommodate the increased demand and variation in the hourly demand cycle, while ensuring grid reliability.

Importantly, the deployment of LDES can help mitigate the need for extensive upgrades to existing grid infrastructure by providing decentralised energy storage options throughout the generation and transmission system.

The transition to renewable energy sources such as wind and solar, which are intermittent by nature, necessitates reliable energy storage to ensure a consistent and stable supply of clean power.

The evolution of LDES
Long-duration energy storage is not a new concept. Pumped hydro-electric storage was first installed in Switzerland in 1907. However, its dependence on suitable geography and available water supply naturally limits its application.

The last two decades have witnessed substantial progress in other LDES technologies, driven by the growing necessity to integrate intermittent renewable energy sources. Recent innovations have encompassed advancements in thermal storage, compressed air energy storage (CAES), and the development of flow batteries and other electrochemical storage methods.

New technologies have achieved higher efficiency, scalability and cost-effectiveness, making them more feasible for widespread, large-scale deployment. One innovation in LDES has been the invention of iron flow batteries that provide a new approach to energy storage.

A key advantage of iron flow LDES is its scalability and flexibility, allowing for integration into various grid applications, from large-scale utility projects to smaller distributed energy storage systems. Additionally, iron flow LDES systems promise cost-effective bulk storage through the use of low-cost materials. Furthermore, these systems are safer and more sustainable than other battery alternatives, thanks to their inherently non-flammable and low toxicity electrolyte which relies upon widely available iron, salt and water.

The global expansion of LDES is rapidly accelerating, with the latest data from the LDES Council indicating that over 8 GW and 80 GWh of capacity are currently either announced or operational worldwide. Projections anticipate even more substantial growth, with forecasts suggesting that by 2040, LDES deployments could range between 2–3 TW in power capacity and 100–160 TWh in energy capacity globally. This trajectory positions LDES to potentially store up to 15% of the world’s electricity consumption by 2040.

Already in action
In the Netherlands, Amsterdam Airport Schiphol aims to enhance its energy efficiency and reduce carbon emissions by integrating an iron flow battery system. The scheme will see the installation of an ‘Energy Warehouse’, an iron flow battery system developed by ESS, to recharge mobile batteries which will replace the diesel ground power units currently used to supply electrical power to aircraft when parked at the airport. A flow battery is an electrochemical cell in which two chemical solutions are separated by a membrane. Ions are exchanged across this membrane, producing chemical energy and electricity.

The adoption of LDES at Schiphol Airport highlights its capacity to support electrified transportation infrastructure and provide reliable power when needed, essential for maintaining uninterrupted airport operations while contributing to environmental sustainability goals.

In Germany meanwhile, Boxberg power station is looking to transform the coal-burning site into what will be the largest clean energy hub in Europe. Lausitz Energie Bergbau (LEAG), which operates four open-cast coal mines in the region, is planning to build an initial 50 MW/500 MWh iron flow battery system, expected to come online in 2027, encouraged by Germany’s commitment to phase out all coal-generated electricity, without the use of natural gas, by 2038.

A greener future
With projections indicating exponential growth in LDES deployments globally, the trajectory is set for long-duration energy storage to become a cornerstone of future energy systems, storing a significant portion of the world’s electricity consumption by 2040.

The views and opinions expressed in this article are strictly those of the author only and are not necessarily given or endorsed by or on behalf of the Energy Institute.

• Further reading: ‘Australia’s first eight-hour battery to be co-located at NSW solar farm’. RWE is to build what will be Australia’s first eight-hour battery near Balranald, in New South Wales.
• The UK Parliament’s Science and Technology Committee’s new report on LDES says the government must act fast to ensure that energy storage technologies can scale up in time to decarbonise the electricity system and ensure energy security by 2035.