The UK Energy Glut: Why Free Electrons Make the Efficiency Argument Irrelevant
The Problem We're Not Talking About
The UK energy glut has arrived — and it's costing consumers £1.8 billion a year. While everyone celebrates the UK's renewable energy records — solar hitting a new generation record of 14.4 GW in March 2026, with the sunniest March since 1910 contributing to a 37% year-on-year surge in solar output — a parallel crisis is unfolding. Ten terawatt-hours of clean power were curtailed in 2025 — enough to power every household in London for a year — deliberately switched off at a cost of £1.8 billion to the system.
The UK energy glut is structural, not seasonal. Solar capacity additions reached 2.8 GW in 2025, with generation up 37% year-on-year. Wind and solar together now generate over 52% of UK electricity. The result: negative electricity prices are projected to double from 149 hours in 2025 to 306 hours in 2026, with 1,000 hours of negative electricity prices forecast by 2027 as renewable capacity continues outpacing demand and grid upgrades. SmartestEnergy's January 2026 analysis confirmed curtailment hit record levels, while Carbon Brief reported that record wind and solar output in March 2026 alone saved £1bn of gas imports — yet the grid still couldn't absorb it all.
The economics are perverse. We pay Scottish wind farms £363 million to switch off while simultaneously firing up gas plants in England to meet demand. Total constraint costs hit £1.8 billion in 2024/25. According to the Montel EnAppSys GB curtailment report, over 98% of the curtailed volume — and 94% of curtailment costs — were due to turning down wind turbines in Scotland, where only 61% of potential wind power makes it to the grid.
Solar is now a major and accelerating driver of the UK energy glut. Unlike wind, which peaks unpredictably, solar creates a highly predictable midday surplus every clear spring and summer day — the “duck curve.” On 1 April 2026, the UK set a new solar generation record of 12.2 GW and wholesale prices collapsed below zero for extended periods. Solar is also geographically dispersed across England and Wales, meaning it compounds the Scottish wind curtailment problem: the grid faces simultaneous surpluses in different regions with limited interconnection. Solar Energy UK confirmed spring 2026 records are being broken repeatedly, with 45 GW of solar capacity targeted by 2030.
I've written before about the economic reality of wind curtailment costs in the UK. This field note focuses on the solution.
Green Hydrogen: Converting Waste Into Value
Green hydrogen production via electrolysis offers a direct pathway to monetise otherwise wasted energy. Electricity costs represent 60–70% of the levelised cost of hydrogen (LCOH), so removing that cost entirely is transformational. My modelling shows the following LCOH scenarios using 2030 assumptions (£400/kW electrolyser CAPEX, 20-year project life, 5% discount rate):
| Scenario | Electricity Source | Capacity Factor | LCOH (2030) |
|---|---|---|---|
| Grid-connected | £50/MWh grid power | 90% | £2.92/kg |
| Hybrid (curtailed + grid) | Mix, avg ~£33.5/MWh | 60% | £2.09/kg |
| Curtailed-only | Free curtailed power | 20% | £1.26/kg |
That £1.26/kg figure is transformational — 57% cheaper than grid-based production and well below the £2/kg threshold widely cited as the tipping point for competitiveness. RenewableUK and Hydrogen UK identified access to curtailed electricity as the single most powerful lever to reduce LCOH.
Shooting Down the Efficiency Argument
Here's where hydrogen sceptics jump in: “But hydrogen is only 35% efficient round-trip! Batteries are 88% efficient!”
This argument is completely irrelevant when the input electricity is free. Let's do the maths on 1 MWh of curtailed renewable electricity — electricity that would otherwise be wasted:
Battery Storage
- Round-trip efficiency: 88%
- Output: 0.88 MWh
- Value at £50/MWh: £44
- Input cost: £0
H₂ → Electricity
- Round-trip efficiency: 35%
- Output: 0.35 MWh
- Value at £50/MWh: £17.50
- Input cost: £0
H₂ Direct Industrial Use
- Electrolysis efficiency: 70%
- Output: 20 kg hydrogen
- Value as industrial fuel: £80
- Input cost: £0
Curtailment
- Nothing produced
- Clean energy wasted
- Bill payers pay £36/MWh
- for not generating
Hydrogen's direct use in industrial applications — steel, chemicals, shipping — creates nearly double the value of battery reconversion to electricity. When the alternative is discarding clean electrons, any positive value creation represents infinite returns.
Complementary Storage — Not Competitive
Batteries, pumped hydro, and hydrogen serve complementary roles across different timescales. The UK's Clean Power 2030 target requires all three. The National Energy System Operator (NESO) estimates flexibility capacity must grow four-to-five times by 2030.
| Technology | Duration | Efficiency | Ideal Use Case | 2030 Target |
|---|---|---|---|---|
| Battery | 0.5–4 hours | 85–90% | Intraday balancing, frequency response | 25 GW |
| Pumped Hydro | 4–24 hours | 70–85% | Daily load shifting, grid stability | ~8 GW |
| Green Hydrogen | Days to months | 30–40% (P2P) / 70% direct | Seasonal storage, industrial decarbonisation | 6 GW electrolysers |
Hydrogen addresses the fundamental challenge of seasonal variation — capturing summer solar abundance for winter use, something batteries and pumped hydro cannot do economically at scale. The recently approved 1.8 GW Earba pumped hydro facility will help with daily balancing, but months-long storage remains the missing piece that only hydrogen can fill.
The Deployment Economics
| Deployment | Curtailed Energy Absorbed | H₂ Production | System Savings/yr | LCOH |
|---|---|---|---|---|
| 1 GW curtailed-only | 1.75 TWh/yr | 35,000 t/yr | £111m | £1.26/kg |
| 3 GW curtailed-only | 5.26 TWh/yr | 105,000 t/yr | £333m | £1.26/kg |
| 3 GW hybrid | 7.88 TWh/yr | 315,000 t/yr | £499m | £1.67/kg |
| 5 GW hybrid | 10.95 TWh/yr | 526,000 t/yr | £667m | £1.88/kg |
The 3 GW hybrid scenario is the sweet spot: absorbing most available curtailment while maintaining sufficient capacity factor to optimise capital utilisation — producing green hydrogen at £1.67/kg while saving the energy system £499 million per year.
What Needs to Happen
- Location-based deployment: Site electrolysers where curtailment occurs — Scotland, north of the B6 transmission boundary. 98% of UK curtailment happens here.
- Curtailment contracts: Instead of paying generators to curtail, contract with electrolysers to provide flexible demand during surplus periods.
- Hybrid operation models: Combine curtailed power with off-peak grid electricity to achieve 50–60% capacity factors and optimise capital recovery.
- Reformed electricity access: NESO's LCOH data confirms near-zero-cost electricity is the single most powerful lever. Policy should enable this, not create barriers through levies on electrolysers.
- LDES support: The government's Long Duration Energy Storage cap-and-floor scheme — with first awards expected in 2026 — provides revenue certainty that improves project bankability.
The Bottom Line
The UK is paying £1.8 billion per year to waste clean energy while struggling to produce affordable green hydrogen. The ClimateXChange analysis and Scottish Enterprise's constrained renewables study both confirm the answer: deploy electrolysers to absorb curtailed power.
With 3–6 GW of strategically deployed electrolysers, the UK can simultaneously:
- Reduce the £1.8bn annual balancing cost burden on consumers
- Produce green hydrogen at £1.26–2.09/kg — competitive with grey hydrogen
- Provide seasonal storage that batteries and pumped hydro cannot deliver at scale
- Accelerate industrial decarbonisation with affordable clean hydrogen feedstock
