Electricity demand on the island of Great Britain has been fully covered by the output of clean-energy sources for a record 87 hours in 2025 to date, new Carbon Brief analysis shows.
This is up from just 2.5 hours in 2021 and 64.5 hours in all of 2024, ahead of the government’s clean-power target for 2030.
The target aims for 95% of the electricity generated in the country in 2030 to come from low-carbon sources, as well as for 100% of national demand to be met without fossil fuels.
The National Energy System Operator (NESO) has a separate target to run the electricity grid without fossil fuels for at least 30 minutes by the end of 2025.
100% clean electricity
The government’s 2030 target has been widely reported as a goal for 95% clean power, with no more than 5% of electricity generation coming from gas.
However, there is a second part to its goal, which is that 100% of national demand in 2030 should be covered by domestic clean-electricity generation.
The two elements mean that the country would need to generate 105% of the electricity it needs – no more than 5% of which would come from gas – with the surplus supply being exported.
The 2030 target relates to electricity supply and demand across the whole year. In 2025 to date, 66% of electricity generation was from nuclear or renewables, which covered 59% of demand. (The difference is due to net imports covering around 17% of demand.)
As such, the 2030 targets are a long way from being met.
Still, there have been an increasing number of periods where 100% of electricity demand on the island of Great Britain has been covered by domestic clean power. (Northern Ireland is part of the separate all-Ireland grid.)
The first ever was a 2.5-hour period from 3.30-6.00am on 30 December 2021, when demand averaged 24.4 gigawatts (GW) and the output from clean-energy sources was 24.9GW.
During 2022-2024, clean-energy supply was sufficient to cover 100% of demand for a total of around 70 hours each year, as shown in the figure below.
In 2025 to date, such periods are becoming increasingly frequent. As of 28 September, demand in Great Britain had been fully covered by clean electricity during a record 87 hours.

This translates to some 1.3% of hours in 2025 to date, far short of the 2030 target. However, this year’s figure is up 50-fold from 0.03% of hours in 2021 – and double the 0.7% share in 2024.
Cleaner electricity mix
During the periods in 2025 to date where at least 100% of demand was being covered by clean generation, wind power was contributing an average of 72% of demand, followed by 18% from nuclear, 10% from solar, 4% from biomass and 1% from hydro.
This means that, in total, low-carbon sources were generating 105% of national demand during such periods in 2025. Over these periods, gas was also generating enough, on average, to meet 13% of demand. As a result, the country was exporting the equivalent of 19% of demand via its interconnectors with Ireland, France, Belgium, Denmark, Norway and the Netherlands.
The figure below illustrates the most recent period when 100% of demand was being covered by clean generation, which took place early on Friday 12 September 2025.
For a four-hour period that morning – from 2am until 6am – clean-energy sources (dark blue) were generating enough electricity to cover 100% of national demand (red line).
During this period, clean sources generated an average of 23.5 gigawatts (GW), including 19.1GW from wind and 3.3GW from nuclear. This was more than the average demand of 22.7GW. Gas still generated an average of 3.1GW (black), resulting in net exports of 4.3GW (light blue).

To date, the record for the longest stretch where 100% of demand was being covered by clean energy stands at 15 hours, from midnight on 25 May 2025 through to 3pm on 26 May.
To meet its clean-power target, the government will need to ensure that this record is extended from just 15 hours in 2025 up to a full year by 2030.
A key test of its ability to do so will come in the seventh auction round for “contracts for difference” (CfDs), which offers fixed-price government-backed deals for new clean-energy developers. The results of this round are due to be announced as early as December 2025.
Until then, NESO will be hoping to meet its target – first set in 2019 – of running the GB grid without any fossil fuels for a short period of time, which it refers to as “zero-carbon operation”.
This target only applies to the transmission grid – effectively, the motorways of the network – meaning it excludes almost all solar power and smaller onshore windfarms.
Craig Dyke, NESO’s director of system operations, previously told Carbon Brief that the first-ever period of at least 30 minutes of “zero-carbon operation” was likely to take place this autumn.
Dyke added that NESO was “confident” it could meet the target, which he said would be “absolutely groundbreaking and pretty much world leading”.
The post Analysis: Great Britain has run on 100% clean power for record 87 hours in 2025 so far appeared first on Carbon Brief.
Analysis: Great Britain has run on 100% clean power for record 87 hours in 2025 so far
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New data shows rich nations likely missed 2025 goal to double adaptation finance
New data on international climate finance for 2023 and 2024 suggests that wealthy countries are highly unlikely to have met their pledge to double funding for adaptation in developing nations to around $40 billion a year by 2025 amid cuts to their overseas aid budgets.
At the COP26 climate summit in Glasgow in 2021, all countries agreed to “urge” developed nations to at least double their funding for adaptation in developing countries from 2019 levels of around $20 billion by 2025. Funding for adaptation has lagged behind money to help reduce emissions and remains the dark spot even as the data showed overall climate finance rose to a record $136.7 billion in 2024.
A United Nations Environment Programme report warned last year that wealthy nations were likely to miss the adaptation finance target and the data released on Thursday by the Organisation for Economic Co-operation and Development (OECD) shows that in 2024 adaptation finance was just under $35 billion.
The OECD, an intergovernmental policy forum for wealthy countries, said the increase between 2022 and 2024 was “modest”, adding that meeting the doubling target would require “strong growth” of close to 20% in 2025.
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The OECD’s figures do not go up to 2025, but several nations announced cuts to climate finance last year. The most notable was the abandonment of US pledges to international climate funds by the new Trump administration but the UK, France, Germany and other wealthy European countries also pared back their contributions.
Joe Thwaites, international finance director at the Natural Resources Defense Council, said developed countries were “not on track” to meet the adaptation funding goal.
Power Shift Africa director Mohamed Adow said adaptation finance is needed to expand flood defences, drought-resistant crops, early warning systems and resilient health services as the world warms, bringing more extreme weather and rising seas. “When that money fails to arrive, people lose homes, harvests and livelihoods – and in the worst cases, their lives,” he warned.
Imane Saidi, a senior researcher at the North Africa-based Imal Initiative, called the $35 billion in adaptation finance in 2024 “a drop in the ocean”, considering that the United Nations estimates the annual adaptation needs of developing countries at between $215 billion and $387 billion.
If confirmed, a failure to meet the goal is likely to further strain relations between developed and developing countries within the UN climate process. A previous pledge to provide $100 billion a year of total climate finance by 2020 was only met two years late, a failure labelled “dismal” by the UAE’s COP28 President Sultan Al Jaber and many other Global South diplomats.
Missing that goal would also raise doubts about donor governments’ commitment to meeting their new post-2025 adaptation finance goal. At COP30 last year, governments agreed to urge developed countries to triple adaptation finance – without defining the baseline – by 2035.
African and other developing countries have pointed to lack of funding as a key flaw in ongoing attempts to set indicators to measure progress on adapting to climate change.
Speaking to climate ministers from around the world in Copenhagen on Wednesday, Turkish COP31 President Murat Kurum stressed the importance of climate finance. “It is easy to say we support global climate action,” he said, “but promises must be kept.”
He said the COP31 Presidency will use the new Global Implementation Accelerator and recommendations in the Baku-to-Belem roadmap, published last year, to scale up climate finance – and will hold donors accountable for their collective finance goals.
He noted that developed countries should this year submit their first reports showing how they will deliver their “fair share” of the new broader finance goal set at COP29 in 2024, to deliver $300 billion a year in climate finance by 2035. They are due to report on this once every two years.
Broader climate finance
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While the OECD does not say which countries provided what amounts, data from the ODI Global think-tank suggests that the 2024 cuts to bilateral climate finance were spread broadly among wealthy nations.
Thwaites of NRDC welcomed the fact that overall climate finance provided and mobilised by developed countries exceeded $130 billion in both 2023 and 2024. He said that this was “well above earlier projections” and “shows that when rich countries work together, they can over-achieve on climate finance goals”.
But Sehr Raheja, programme officer at the Delhi-based Centre for Science and Environment, said these figures are “modest” when set against the new $300-billion goal.
“While the headline total figure of climate finance remains alright,” she said, “declining bilateral climate spending raises important questions about the predictability of high-quality, concessional public finance, which has consistently been a key demand of the Global South.”
She also lamented that loans continue to dominate public climate finance and that mobilised private finance is concentrated in middle-income countries and on emissions-reduction measures rather than adaptation projects. “Private capital continues to follow bankability rather than climate vulnerability or need,” she added.
Ritu Bharadwaj, climate finance and resilience researcher at the International Institute for Environment and Development, said the figures painted an outdated picture as climate finance has since declined as rich countries shrink their overseas aid budgets and increase spending on defence.
Last month, the OECD published figures showing that international aid – which includes climate finance – fell by nearly a quarter in 2025. The US was responsible for three-quarters of this decline. The OECD projects a further decline in 2026.
With Thursday’s climate finance report, the OECD is “publishing a victory lap for 2023 and 2024 at almost the same moment its own aid statistics show the funding base eroding underneath it,” Bharadwaj said.
The post New data shows rich nations likely missed 2025 goal to double adaptation finance appeared first on Climate Home News.
New data shows rich nations likely missed 2025 goal to double adaptation finance
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