Long-duration energy storage: the key to power decarbonisation
Why is long-duration energy storage essential?
On the road to a cleaner, safer and more resilient power system, long-term energy storage is an essential solution to ensure supply stability on the path to a zero-emission model. From advanced chemical batteries to thermal, mechanical and gravitational solutions, the development of new storage capacities not only multiplies the use of clean energy, but also drives efficiency, innovation and energy independence.
Long-duration energy storage (LDES) refers to systems capable of storing energy for more than 8–12 hours — and in some cases days or weeks — to release it when needed. Unlike storage solutions that last only a few hours, such as conventional batteries, LDES can balance energy supply and demand over time, making it possible to integrate massive amounts of renewable energies, reducing dependence on fossil fuels and improving the stability of the electricity grid.
Each technology has its strengths, so the different technologies need to be compared and the one that best suits the needs to be met chosen.
Overcoming the intermittency of renewable energies
Solar and wind energy, although clean and abundant, are variable by nature, as they depend on the weather. Their use requires adapting the planning and operation of the electricity system to ensure a continuous and stable supply. This variability poses technical challenges such as frequency management, balancing supply and demand in real time, and responding quickly to unforeseen changes.
To address these challenges, complementary solutions are being deployed to strengthen the energy system: storage technologies such as batteries or hydraulic pumping systems; smart grids that optimise energy flow; improvements in weather forecasting models; and greater cross-country communication to share surpluses and increase grid resilience.
What is Energy Storage
Keys to current technologies and why they are so necessary.
Battery Sizes
Battery dimensions: their importance and their influence on performance
Sodium-Ion Batteries
The revolution in renewable energy storage
Lithium-Ion Batteries
Essential for energy storage
Ensuring supply stability and security
Although there are technological solutions to the challenges of intermittency, the real challenge in achieving a sustainable energy model lies in ensuring the stability and security of electricity supply in a system with a high penetration of renewable energies. The key is to combine several strategies: strengthening grid infrastructure, diversifying the energy mix, increasing operational flexibility and deploying energy storage technologies.
Storage — in the form of batteries or hydraulic pumping — allows renewable surpluses to be absorbed and released at times when generation is low, ensuring a constant and reliable flow of power. Other elements such as advanced control systems, grid-forming inverters and improved international interconnections, which are essential to respond quickly to imbalances, are also key.
All of this, backed by decentralised territorial planning and regulation that encourages resilience and quality of supply, is essential to ensure that the transition to a cleaner energy model does not compromise the power system’s security and stability.
Enabler of a 100% renewable electricity grid
Long-duration storage is the key enabler for a 100% renewable electricity grid. This is because it allows clean surpluses to be stored and released when production is low, ensuring a continuous and reliable supply. It brings flexibility and stability to the electricity system, makes it possible to integrate massive amounts of renewables and prevents wasting clean energy. It also improves efficiency and drives decarbonisation.
To achieve this, a set of enabling technologies and strategies must be deployed:
Digitalisation of smart grids
Digitalisation transforms the traditional electricity grid into a dynamic, automated and data-driven infrastructure. Smart grids use sensors, automation, artificial intelligence and advanced communication systems to monitor and operate the system in real time.
Advanced control technologies (grid forming)
Grid forming technology is key to the stability of a 100% renewable grid. With it, renewable generation and storage systems can act as virtual synchronous generators, providing synthetic inertia and stabilising the grid in the event of sudden frequency variations.
Infrastructure expansion and modernisation
The reinforcement and modernisation of transmission and distribution girds are essential to evacuate renewable generation from high-potential areas and avoid bottlenecks. Technologies such as Dynamic Line Rating (DLR) make it possible to increase the capacity of existing lines by up to 30%, optimising the use of infrastructure and integrate more clean energy.
Storage and flexibility
Energy storage, both large-scale and distributed, is a fundamental pillar for absorbing renewable surpluses and releasing power when production is low. Together with active demand management and sector coupling (integration with transport, heating or green hydrogen production), this makes the grid more flexible and resilient, capable of adapting to fluctuations in renewable generation.
Integrated planning and innovative regulation
The transition to a fully renewable grid requires integrated energy planning that considers generation, transmission, storage and consumption, as well as regulatory frameworks that drive innovation, the public’s participation and investment in new technologies. Examples such as the Renewable Energy Control Centre (Cecre) in Spain demonstrate the importance of real-time monitoring and control to maintain the quality and security of supply.
A 100% renewable electricity grid is technically feasible and increasingly necessary to achieve decarbonisation targets. Its implementation depends on a combination of digital technologies, storage, reinforced infrastructure and smart and flexible management of the electricity system, under regulations that encourage innovation and resilience.
These technologies are aligned with global trends in the industry and backed by market reports that project exponential growth: the global energy storage market is estimated to reach $620B by 2025, driven by the massive adoption of renewables and technological innovation.
The integration of artificial intelligence into these systems will also optimise loading and offloading, improve operational efficiency, extend service life and anticipate grid imbalances through predictive analytics.
Many of these solutions are being developed with modular and scalable approaches, making it possible to roll them out at residential, commercial and industrial levels. This flexible approach is key to building a more resilient, sustainable and 100% renewable electricity grid.
Strategic benefits of long-term energy storage
Beyond its technical role in stabilising the electricity system, long-duration energy storage offers key strategic benefits that position it as a fundamental tool for the future of energy. Some of these benefits are:
Electrical system stability and security:
by enabling better management of generation and demand imbalances, even when renewable production is low or unpredictable.
Acceleration of decarbonisation:
thanks to a more efficient integration of clean sources without compromising continuity of supply.
Greater grid resilience:
by providing backup in the event of extreme events, consumption peaks or unexpected interruptions in generation.
Optimisation of resources and economic efficiency:
by reducing waste of unused renewable energy and decreasing the need to maintain fossil fuel infrastructure as a backup.
Strengthening energy independence:
by reducing dependence on fossil fuel imports and diversifying backup sources.
Boosting innovation and the green economy:
by encouraging the creation of new business models, attracting technological investment and creating skilled jobs.
Flexible and smart grid management:
with advanced services such as energy arbitrage, frequency regulation and decongestion of critical nodes.
Together, these benefits make long-duration storage a strategic element in ensuring the sustainability, competitiveness and security of the energy system of the future.
Challenges and barriers to large-scale implementation
Despite technological advances, long-duration energy storage faces some challenges to its mass deployment. The main obstacles include high investment and operating costs, especially in emerging technologies that have not yet achieved economies of scale. The volatility in the price of raw materials such as lithium and nickel hinders structural cost reduction and limits competitiveness compared to conventional solutions.
There are also regulatory and administrative barriers, such as the lack of a clear regulatory framework, red tape and the absence of well-defined capacity markets that encourage private investment. Access to the electricity grid and the need to adapt infrastructure to integrate storage systems also pose significant technical and logistical challenges. Finally, the lack of robust business models and mechanisms to monetise the services provided by storage (such as demand management, energy arbitrage or grid backup) slows down its large-scale adoption.
Iberdrola's role in promoting long-term storage
Iberdrola is one of the key players in promoting long-duration energy storage worldwide. The company is leading flagship pumped hydro storage projects and investing in advanced technologies such as large-capacity batteries and hybrid systems, integrating storage with renewables to maximise the use of clean energy.
We also actively participate in the development of new business models and public–private partnerships to accelerate the integration of these technologies into the electricity system. In addition, we support innovation and industrialisation in the industry, creating jobs and strengthening the national value chain in energy storage. Our strategic commitment strengthens the resilience of the grid and facilitates the transition to a more sustainable and secure energy system, in line with the climate and energy independence objectives of Spain and Europe.