Five energy technologies to watch in 2026 as the UK’s flexibility challenge comes into focus

For much of the past decade, the energy debate has focused on adding capacity. That phase is largely over. The next challenge is managing variability, when supply and demand no longer line up neatly, and resilience depends on how well the system can adapt. Against that backdrop, a handful of technologies are emerging as central to how the UK thinks about flexibility. Here we look at five tech areas that are looking to address this issue.

1) Long-duration energy storage beyond lithium-ion

Short-duration batteries have moved rapidly from niche to mainstream. What they have not solved is endurance. As variable renewables take a larger share of the system, attention is shifting towards storage technologies that can operate for tens of hours or longer, rather than simply smoothing intraday peaks.

The International Energy Agency (IEA) consistently draws this distinction. Lithium-ion batteries are highly effective for fast response and short-cycle balancing, but they are not designed to provide multi-day or seasonal resilience at scale. BloombergNEF’s analysis reinforces this view, showing continued growth in battery deployment alongside rising interest in alternatives that prioritise duration over power density.

At the research end of the pipeline, laboratory advances are also pushing diversification. Recent academic work on faster-charging sodium-ion batteries points to efforts to reduce safety risks and supply-chain exposure associated with lithium, even if large-scale deployment remains some way off.

What has changed most in the past two years is not a breakthrough in chemistry, but in expectations. Long-duration storage is increasingly seen as a complementary layer in the flexibility stack, rather than a like-for-like replacement for lithium-ion.

2) Hybrid flexibility systems: combining storage, demand, and networks

One of the clearest indicators from UK policy is that flexibility is no longer expected to come from standalone assets. The Department for Energy Security & Net Zero (DESNZ) Clean flexibility roadmap explicitly frames the future energy system as one in which flexibility is delivered through combinations of storage, demand-side response, interconnection, and controllable generation.

That shift matters because it changes how innovation is judged. Instead of asking which technology will “win”, planners are focused on how assets interact under stress. Hybrid configurations – batteries paired with flexible demand, or storage optimised alongside interconnectors – are increasingly treated as the default assumption rather than an edge case.National Grid ESO’s system planning reinforces this direction, with future scenarios built around coordination and optionality rather than single-asset solutions. The implication is clear: value is moving away from raw capacity and towards orchestration.

3) Hydrogen storage as long-duration, system-stress infrastructure

Hydrogen storage has moved into a narrower, but arguably more credible, role. Rather than being positioned as a general balancing solution, it is increasingly discussed as an option for rare but severe system stress – prolonged periods of low renewable output, seasonal imbalances, or industrial resilience.

That reframing is reflected in recent government-commissioned analysis. Work by Baringa Partners for DESNZ on hydrogen-to-power highlights turbine derating, start-up requirements, and rising system costs when hydrogen is expected to operate frequently. Separate DESNZ-backed research into the geomechanics of hydrogen storage in salt caverns is equally direct about geological limits and the operational consequences of frequent cycling.

UK research is also starting to focus more directly on how hydrogen would be used in a real energy system. One example is the HyDUS project, led by the University of Bristol, EDF and Urenco. Rather than treating hydrogen as a standalone solution, the project looks at how hydrogen storage and use would sit alongside other flexibility options such as batteries, demand-side response and grid constraints. The aim is to understand practical questions, such as how often hydrogen would be used, in what situations, and what that means for infrastructure design, rather than assuming it runs all the time.That approach reflects a broader shift in the hydrogen debate, away from ambition-led targets and towards evidence about where hydrogen can play a useful, but limited, role. Market outlooks point in the same direction. Wood Mackenzie argues that hydrogen deployment is entering a more selective phase, shaped by capital discipline and the need for firm offtake rather than broad ambition. Cost remains a further constraint. PwC’s analysis underlines that green hydrogen competitiveness depends heavily on electricity prices, utilisation rates, and policy support, reinforcing why storage economics remain challenging.

4) Mechanical and gravity-based storage: old physics, new constraints

Mechanical storage technologies, including pumped hydro, compressed air, and liquid air energy storage, sit in a corner of the energy debate, but one with growing relevance. Their appeal lies in durability. These are long-life assets with relatively low degradation and limited exposure to volatile materials supply chains.

The IEA continues to highlight mechanical storage as a credible option for medium- to long-duration flexibility, particularly where geography and infrastructure align. In the UK, recent innovation has focused less on reinventing the physics and more on expanding the range of viable sites. Projects using higher-density fluids aim to make pumped storage feasible beyond traditional mountainous locations.

This is a story of incremental, infrastructure-led deployment, rather than rapid scaling.

5) Digital optimisation and AI-enabled flexibility

The least visible, but potentially most influential, innovation trend is digital. As flexibility assets multiply, the energy system becomes harder to operate using static assumptions and manual intervention alone. Advanced forecasting, optimisation and predictive-maintenance tools are increasingly used to extract more value from existing infrastructure.

The IEA identifies digitalisation as a critical enabler of future energy systems as complexity rises. The World Economic Forum takes a similar view, framing AI and digital tools as system-level enablers that improve coordination and efficiency rather than driving demand in their own right.

In this context, AI acts as a force multiplier. It does not replace physical infrastructure, but it influences how much of it is needed, and how hard it is worked.