Government publishes results of £70m long-duration storage demonstrations

What happened

In July 2026, the Department for Energy Security and Net Zero (DESNZ) published the final reports from its Longer Duration Energy Storage Demonstration (LODES) programme, closing out a five-year, roughly £70m effort to test technologies that can store energy for days, weeks or months. The gov.uk programme collection records final-report updates on 7 and 24 July 2026, with trade coverage following on 27 July.

The programme, which ran from 2021 to 2026, was split into two streams: Stream 1, around £15m for later-stage technologies, and Stream 2, around £55m of SBRI contracts for more novel approaches. Stream 2's second phase funded seven projects through to built, working demonstrators. Lithium-ion, conventional pumped hydro and large hot-water tanks were explicitly out of scope — the point was to test what does not yet exist at commercial scale.

The technology

The seven Stream 2 demonstrators cover a deliberately wide spread. StorTera received £5m to build a single-liquid flow battery near Edinburgh: eight modules combining into a 200kW, 1.6MWh system using recyclable materials and wood-industry by-products. Cheesecake Energy's £9.4m FlexiTanker pairs compressed air with thermal storage, with pilot units linked to a Colchester microgrid alongside up to 8MW of solar and a heat network.

RheEnergise took £8.2m for its high-density hydro system, which pumps a fluid denser than water to make pumped storage viable on smaller hills; its prototype delivers 250kW with four hours of storage. SynchroStor's £9.4m pumped-thermal demonstrator converts electricity to heat and back, targeting a grid-connected megawatt-scale plant with ten hours of storage. EDF's £7.7m HyDUS project stores hydrogen in depleted uranium, adapting technology from the fusion industry for safe long-term storage and release.

Two projects tackled heat directly. Sunamp's £9.2m EXTEND trial put thermal batteries with smart controls into 100 UK homes, testing whether fleets of domestic heat stores can help networks ride through low-renewable periods. The University of Sheffield's £2.6m ADSorB project built modular residential heat storage with intelligent controls, with prototypes installed at the University of Nottingham's Creative Energy Homes campus.

According to the published summaries, all seven schemes progressed from feasibility study to full prototype development and demonstration.

Why it matters for UK & Ireland

Britain's decarbonising grid has a well-documented weakness: the extended wind lull. Batteries shift energy by the hour; the hard problem is a still, cold fortnight in January. The government announced a cap-and-floor support regime for long-duration storage in October 2024, administered by Ofgem, with a target of 4–6GW of capacity by 2030 — but regulators and investors need evidence about which technologies actually work, at what cost, and at what round-trip efficiency.

LODES is that evidence base, publicly available, from seven different technical routes tested on UK sites from Edinburgh to Colchester. The House of Lords Science and Technology Committee warned in March 2024 that the rollout was "not being treated with sufficient urgency", noting that large facilities can take seven to ten years to build.

The findings travel well across the Irish Sea. Ireland's wind-heavy grid faces the same low-wind-week arithmetic, and demonstrated, documented UK results on flow batteries, compressed air and domestic thermal fleets shorten the appraisal work for Irish planners considering the same options.

What to watch

The distance from a 200kW or 250kW prototype to a grid-relevant plant is measured in orders of magnitude, and in money. The immediate question is which of the seven graduate into the cap-and-floor regime's project pipeline, and which quietly stop at the demonstrator stage.

Watch for commercial follow-on announcements from StorTera, RheEnergise, SynchroStor and Cheesecake Energy in particular, and for whether the household-scale results from Sunamp and Sheffield feed into network flexibility markets. One caution on the record itself: the reports were published across July 2026 in stages, and the headline claims about each technology's performance are, for now, the participants' own — independent scrutiny of the final reports is the next useful step.