Energy breakthrough: How long-duration storage could solve the renewable puzzle

Lithium-ion batteries can power minutes. Long-duration energy storage can power days — and reshape entire power systems.

If lithium batteries are sprinters, long-duration energy storage (LDES) is the marathon runner the energy transition desperately needs.

LDES includes pumped hydro, compressed air, flow batteries, thermal storage, and gravity-based systems.

long-duration energy storage is the real game-changer in clean energy: Turns out it isn’t just more solar or wind — it’s storage that lasts beyond sunset, storms, and grid shocks.

This solution offers a number of benefits: it raises reliability of energy and system flexiblity, while reducing overall cost.

In other words, it's not just simple energy storage: It ramps up overall value.

LDES refers to technologies that can store energy for extended periods, typically 8 hours or more, and release it when needed.

These solutions are vital for balancing intermittent renewable sources like solar and wind, ensuring grid stability during low production periods.

For instance, pumped hydro stores energy by pumping water uphill and generating power as it flows down.

As countries shift to low-carbon power systems, renewables are expected to dominate electricity generation.

However, solar and wind are variable, creating mismatches between supply and demand.

LDES addresses this by storing excess energy for days or weeks, improving reliability, reducing costs, and cutting emissions.

IRENA reports show LDES could enable up to 90% renewable integration in grids, delivering system-wide savings.

Without it, grids risk blackouts or reliance on fossil fuels.

Global deployment is accelerating, with targets like California's 1 GW of multi-day LDES by 2037.

It's just the tip of the iceberg: India already has 10 operational PSHP projects, with a total capacity of ≈7.2 GW, the an additional 10 projects totaling about 11.6 GW of capacity being built.

There's a massive pipeline of future capacity with total of ~74 GW generating capacity is in early planning stages.

China, for its part has over 75 pumped hydro power stations either in operation or currently being built, with a total combined capacity of around 94 GW, as per industry sources.

China’s national plans targeted around 120 GW by 2030, likely reaching ~130 GW this decade.

The International Renewable Energy Agency (Irena), based in Abu Dhabi, works with the Long Duration Energy Storage Council (LDESCouncil) co-hosting webinar series titled "Unlocking the Value of LDES."

It builds on IRENA's work in renewable integration and LDESCouncil's advocacy for storage tech.

According to the Irena, LDES provides system-wide value, not just energy storage

Among policy makers, LDES is gaining greater attention.

For example, the EU's Electricity Market Design requires member states to evaluate flexibility needs, prioritising non-fossil solutions like LDES.

The European electricity market is the largest integrated electricity market in the world, using 11.3 million km of power lines and cables across the EU alone -- enough to encircle the Earth 282 times -- to bring electricity to 266 million customers.

An integrated EU energy market is the most cost-effective way to ensure secure, sustainable and affordable energy supplies to EU citizens.

Common energy market rules and cross-border infrastructure allows energy to be produced in one EU country and delivered in another.

The EU internal energy market saves consumers €34 billion annually and, with deeper integration, this could rise to €40-43 billion by 2030.

The European Commission seeks deeper electricity market integration in the continent, ‘White Paper’ onis due for publication in early 2026.

The session highlights real-world deployments, such as Ireland's 2.8 GW LDES need for an 80% renewable grid by 2030.

Challenges include high upfront costs, uncertain revenues, and regulatory gaps.

Solutions involve policy signals like targets (e.g., China's 120 GW pumped storage by 2030) and funding mechanisms.

Market designs must value LDES's flexibility, such as through capacity markets or long-term contracts.

Reports emphasise assessments of LDES needs, like in Australia and the UK, to attract investments and ensure technology diversity.

Irena reckons that pricing signals can accelerate LDES scaling, while regulatory frameworks woulc increase bankability, revenue certainty, and fair competition.