Long-duration energy storage: Are we there yet?

As the world accelerates towards net zero, one challenge continues to dominate the energy conversation: how do we store renewable energy for long enough to keep power flowing when solar and wind generation drops?

The answer may lie in long-duration energy storage (LDES) – one of the fastest-growing sectors in the global energy transition.

But while investment and interest continue to rise, the question remains: are we actually there yet?

What is long-duration energy storage?

Long-duration energy storage refers to technologies capable of storing electricity for extended periods, typically 8 hours or longer.

Unlike short-duration battery systems designed for rapid balancing and peak shaving, LDES technologies are intended to provide longer-term backup power, improve grid resilience and support renewable-heavy energy systems. As renewable penetration increases, grids must also cope with longer periods of low generation caused by weather changes, seasonal demand fluctuations and extended periods of low wind or solar output.

Why is long-duration energy storage important?

1. Renewable energy is intermittent

Solar panels only generate electricity during daylight hours, while wind generation fluctuates based on weather conditions.

Long-duration storage allows excess renewable electricity to be captured and used later when generation falls.

This is critical for achieving:

• Stable electricity grids

• Reduced fossil fuel dependence

• Lower carbon emissions

• Energy independence

2. Grid stability is becoming more challenging

As coal and gas plants retire, power systems lose traditional sources of grid inertia and dispatchable generation.

LDES technologies can help provide:

• Capacity reserves

• Frequency regulation

• Peak demand support

• Emergency backup power

This matters even more as electricity demand continues to grow through:

• EV adoption

• Electrification of heating

• AI and hyperscale data centres

• Industrial decarbonisation

3. AI and data centres are driving new demand

The rapid growth of AI infrastructure is significantly increasing electricity demand worldwide.

Hyperscale data centres require:

• Continuous uptime

• Reliable power quality

• Low-carbon energy supply

This is creating strong commercial interest in long-duration storage solutions capable of supporting 24/7 clean power strategies..

The technologies shaping the LDES market

There is currently no single technology dominating the LDES market. Instead, several different solutions are emerging.

Pumped hydro remains the most established form of long-duration storage. It works by pumping water uphill using excess electricity and releasing it through turbines when power is needed. The technology is proven and reliable, although projects can be expensive and geographically limited.

Flow batteries are attracting growing interest from industry. Unlike lithium-ion batteries, they store energy in liquid electrolytes, making them better suited to longer discharge durations. They also offer strong safety and lifespan advantages, although costs remain relatively high.

Iron-air batteries have generated significant attention in recent years due to their potential to deliver low-cost, multi-day storage using abundant materials such as iron, water and air. While promising, the technology is still in the early stages of commercial deployment.

Compressed air energy storage (CAES) is also attracting investment. These systems store excess energy by compressing air and releasing it later to generate electricity. Although the technology offers strong potential for large-scale storage, infrastructure and efficiency challenges still need to be addressed.

So, are we there yet?

The short answer is: not quite.

The technology itself is no longer the main challenge. Many long-duration storage systems are already operating successfully across pilot and commercial projects worldwide. Governments are introducing support schemes, and private investment in the sector continues to rise.

However, the industry still faces several barriers. Costs remain high compared to more established technologies like lithium-ion batteries, and electricity markets are not always structured in a way that rewards long-duration storage properly. Many technologies also still need to prove themselves at a larger commercial scale.

Even so, the sector is moving in a positive direction. As renewable energy deployment accelerates, the need for longer-duration storage will only increase. The sector may not yet be fully mature, but it is moving closer to becoming a critical part of the future energy system.

For more insights into energy storage, backup power and the technologies shaping the future, explore the latest articles from DMS technologies.