Emissions from the new data centres set to drive the UK’s AI “revolution” could be hundreds of times higher than government estimates, according to analysis by Carbon Brief.

There are dozens of data centres being developed across the country, potentially driving a surge in electricity demand.

Amid uncertainty about the scale and pace of this expansion, there are mounting concerns that new data centres could pose a threat to the nation’s climate goals.

UK government analysis concluded that the emissions from data centres would be negligible, even if they expand rapidly – a finding one campaigner tells Carbon Brief is “nonsense”.

In contrast, Carbon Brief analysis finds that emissions from powering data centres could be far higher than the government figures suggest, if at least a small amount of the electricity they need is generated by burning gas.

Data centres could run entirely on low-carbon electricity, but some in the sector have argued that the government’s AI ambitions require the UK to use more gas power.

If new data centres source a large amount of their power from gas, it could cause carbon dioxide (CO2) emissions equivalent to at least Denmark’s annual total.

‘AI superpower’

Data centres are energy-intensive computing facilities that are required to train and run complex AI models, among many other things.

The UK is one of the top-ranking nations for data-centre capacity, with roughly 1.8 gigawatts (GW) of facilities consuming more than 2% of national electricity. This could grow rapidly in the coming years as the government aims to make the UK an “AI superpower”.

Companies have already “achieved financial commitment” to invest in 71 new data centres that, if built, would require around 20GW of electricity, according to energy regulator Ofgem.

(For reference, the UK’s average electricity demand in 2025 stood at around 37GW.)

This potential increase in electricity demand has raised concerns from campaigners and some MPs about the impact of data centres on the UK’s climate targets.

Last year, the government’s plan for meeting its 2035 climate target noted that AI growth was “not factored into” emissions projections, although energy secretary Ed Miliband has said new data centres are captured in modelling of “overall electricity demand growth”.

The government is targeting a “clean power system” by 2030, with just a small amount of gas generation remaining. Extra demand from new data centres could require a rollout of clean power that is even faster than the growth already underway.

If clean-power growth does not keep pace, data centres could, therefore, prolong the use of gas power, either by requiring more gas to remain on the grid or by facilities building their own on-site gas generation.

There is significant uncertainty around future emissions from UK data centres, which will depend on the number of centres built, how clean their power is and when they come online.

The government published an analysis of its AI strategy’s climate impact last year, alongside a data-centre “roadmap”.

The analysis, released by the Department for Science, Innovation and Technology (DSIT) suggests emissions from future data centres will be minimal – reaching a maximum of 0.142m tonnes of CO2 (MtCO2) from 11.2GW of AI-related computing power by 2035.

(There is an additional 2.4GW of data-centre demand in this scenario that is not associated with AI, for which emissions are not calculated.)

This figure is based on what DSIT describes as a high-emissions, high-AI growth scenario. Yet it implies that each unit (kilowatt hour, kWh) of electricity supplied to the 11.2GW of AI data centres would be associated with less than 2g of CO2. In other words, their electricity supply would need to be almost completely decarbonised. The government aim is for 50gCO2/kWh by 2030.

In addition, the DSIT figure – for emissions associated with the entire UK data centre fleet in 2035 – is much lower than the emissions estimates reported in planning applications for individual UK data centres made by Google and other companies.

Gas power

The chart below, based on Carbon Brief analysis, shows how data-centre emissions could be far higher than the government’s figures suggest.

Even if gas-fired electricity only accounts for 5% of their supply – indicated by the smallest blue column below – emissions from 11.2GW of data centres would be around 2MtCO2. This is more than 10 times higher than the government’s top estimate for 2035.

If the same data centres rely more heavily on gas, emissions could be hundreds of times higher, exceeding 30MtCO2. This is roughly equivalent to the annual emissions of Denmark. Emissions could rise even higher if capacity increases in line with the extra 20GW of data-centre demand that Ofgem says is in the pipeline, as indicated by the red columns

If data-centre expansion reaches 20GW and those centres rely heavily on gas power, then the figure could be as high as 70MtCO2, the annual emissions of Sweden. This would also be nearly 500 times higher than the government’s upper estimate, which it says is based on a “pessimistic decarbonisation” scenario.

(The numbers are not directly comparable as, unlike the AI-specific 11.2GW figure, it is unclear how much of this 20GW would be for AI, specifically.)

The government’s modelling states that AI emissions in 2035 would be “equivalent to below 0.05% of the UK’s projected total emissions”. It also says “this could be equivalent to the annual emissions of approximately 5,000 to 23,600 UK households”.

On the contrary, Carbon Brief’s analysis suggests data centres could, in fact, be equivalent to as much as 20% of the UK’s projected total emissions in 2035.

As for the number of households, Carbon Brief estimates that future data centres could result in emissions equivalent to as many as 11.4m homes, roughly a third of all UK households.

Dr Tim Squirrel, head of strategy at Foxglove – part of an NGO group calling for more government scrutiny of data-centre emissions – tells Carbon Brief the DSIT figures are “nonsense and threaten to derail our carbon budgets”. He says:

“The figures that DSIT projects here wildly downplay data-centre emissions, even by the standards of the most optimistic energy transition scenario. There is no way that the amount of compute they anticipate can be built and produce the miniscule emissions they’re calculating.”

In its analysis, the government attributes the low emissions figures to “more efficient models and hardware” and “the UK’s ambitious targets for electricity grid decarbonisation”.

When asked by Carbon Brief, DSIT declined to provide any more information about its analysis.

Clean growth

While the UK is prioritising data centres for AI, there is mounting industry pressure to allow gas-power expansion for this “critical” infrastructure, as is happening in, for example, the US and Ireland.

Developers in the UK have reportedly already “turned to gas” via private electricity supplies, due to struggles securing a connection to the public network.

Yet, new data centres could be completely emissions-free if they are powered entirely with on-site clean energy or using electricity from a decarbonised grid.

As it stands, most data centres are connected to the electricity grid. Some enter power purchase agreements (PPAs) in which they financially support renewable-energy operators, allowing them to describe their electricity as clean.

Katie Davies, head of energy and infrastructure policy at techUK, a trade association representing the technology sector, highlights this expansion of PPAs as important for driving the growth of wind and solar power:

“In doing so, data centres actively contribute to additionality by unlocking extra carbon-free capacity that might not otherwise come online.”

A report last year by Aurora Energy Research found that data centres could provide a “route-to-market” worth up to £35bn for 19GW of UK renewables. However, it added:

“If renewables capacity and networks don’t keep pace, additional data centre demand will likely be met by carbon-intensive sources of generation.”

The UK’s “AI opportunities action plan” includes the establishment of “AI growth zones“, which the government says will be in areas with “available clean energy”. It is also overhauling the grid connection queue, which Davies says is important:

“Reducing this queue through strategic alignment and the removal of speculative applications will be vital to ensuring [data-centre] operators do not have to turn to higher-carbon energy sources as a last resort.”

Responding to Carbon Brief’s analysis, a government spokesperson said:

“We want the UK to be at the forefront of AI, but we are clear this must be done sustainably. That is why our AI growth zones are supporting development in areas with access to clean power, while the AI Energy Council is exploring how AI can be powered by responsible, clean-energy sources.”

Methodology

There is considerable uncertainty around data-centre power demand and emissions, with much of the relevant information not in the public domain. Carbon Brief has performed some rough calculations based on available data.

The government figure comes from an annex to DSIT’s UK compute roadmap. DSIT analyses the emissions impact of expanding the UK’s data-centre capacity to between 7.4GW in a “low compute-demand scenario” and 13.6GW in a “high compute-demand scenario” by 2035. (The majority of the demand in each scenario is from AI.)

DSIT also uses an “AI environmental impacts model” to estimate the greenhouse gas emissions from AI compute, only covering the 11.2GW AI component of data-centre capacity. It concludes that AI emissions in 2035 could range from 0.025MtCO2 to 0.142MtCO2. This includes both “direct” and “indirect” emissions, indicating that it covers more than just emissions from the electricity used to power the data centres.

A widely reported consultation by the energy regulator, Ofgem, found that there are proposals for around 140 new data centres in the UK, which would require 50GW of electricity if they were all built.

In reality, it is highly unlikely that all of these data centres will be completed, with a “significant number” expected to fail when trying to secure funding or planning permission.

The 20GW figure used in this analysis is based on the 71 “mature” projects that have “achieved financial commitment with final investment decision”, according to Ofgem.

Carbon Brief used the top government figure of 0.142MtCO2, even though it represents a “pessimistic grid decarbonisation” and “high compute demand” scenario.

To calculate the emissions from powering data centres in the future, Carbon Brief assumes a data-centre “load factor” of 90%, which is in line with other analyses. The analysis uses different shares of gas in the centres’ power supplies to indicate a range of future possibilities, assuming emissions from gas power are 0.4MtCO2 per terawatt hour.

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The post Analysis: CO2 from UK data centres could be ‘hundreds of times’ higher than thought appeared first on Carbon Brief.

Analysis: CO2 from UK data centres could be ‘hundreds of times’ higher than thought

The world’s largest producer of renewable fuel for planes, Neste, is sourcing key ingredients for its “green” fuel from an opaque supply chain that enables fresh palm oil to be passed off as waste, highlighting a global problem facing the aviation industry.

Many governments and airlines are pinning their hopes for more climate-friendly flying on sustainable aviation fuel (SAF). Finnish biofuels giant Neste says it makes SAF with 100% “renewable waste and residue raw material”, such as animal fat and used cooking oil (UCO).

But Climate Home News and Swedish broadcaster SVT found that Neste’s biggest Malaysian supplier of UCO accepted fresh palm oil during a public drive intended to collect waste oil, without asking questions or carrying out checks.

Our investigation did not uncover direct evidence that this or other virgin palm oil has been used by Neste to produce SAF. But industry experts say that, once oil supplies are mixed at source, it is hard for refiners to keep it out of their supply chain.

Neste indicated it would look into our findings, adding that it is currently not aware of any verified cases of fraud that are directly connected to its raw material sourcing.

Planet-heating palm oil

Mounting evidence of widespread fraud risks in the SAF supply chain raises doubts about the climate benefits of the aviation sector’s main green strategy for the years ahead, analysts say.

Palm oil that has not been used for cooking or frying is not permitted under rules on which raw materials can be made into SAF supplied in Europe, Neste’s largest market, because of its links to deforestation.

The clearing of forests for palm oil plantations in Southeast Asia and beyond has long been associated with the loss of carbon-storing jungle, posing a threat to efforts to tackle planet-heating emissions and protect endangered wildlife.

Analysis of Malaysian custom records indicates that Neste sourced around 250,000 tonnes of UCO from Malaysia in 2024. That is more than double the total amount collected in the country annually, according to estimates published by Brussels-based NGO Transport and Environment (T&E). Discrepancies like these have fuelled suspicions about what UCO shipments from Malaysia contain.

A former director at Neste, speaking on condition of anonymity, told Climate Home News that, while the Finnish firm is a highly professional operator, no fuel producer can claim with 100% certainty that its supply chain does not include virgin palm oil or mislabelled raw materials due to the complexity of the sector and weak enforcement by regulators.

The findings add to questions about the integrity of green jet fuel after an investigation by Climate Home News and The Straits Times last year uncovered similar flaws in the supply chain. With more countries mandating the use of small but growing amounts of SAF, and fuel producers scrambling for limited raw materials, barely used and virgin palm oil is being passed off as UCO to traders, industry sources told us.

‘Very high’ fraud incidence

Demand for SAF has surged as governments and airlines promise to cut emissions from a sector with few low-carbon alternatives. Its backers say SAF can reduce planet-heating emissions by up to 80% over kerosene jet fuel when made with waste materials like used cooking oil that do not take up land for food crops or drive deforestation.

But the growing gap between what the world’s kitchens and food factories can realistically provide and what the aviation industry requires has created a clear incentive for fraud.

Is the world’s big idea for greener air travel a flight of fancy?

That holds true in Malaysia, a key sourcing country for SAF suppliers like Neste, where government-subsidised palm oil for cooking can be bought cheaply and then sold on for a higher price as UCO. For that reason, there are additional requirements that the oil should not be deliberately contaminated or manipulated for profit.

“The opportunity, or incidents, of fraud is very high,” Vasu R Vasuthewan, former Malaysia head for the ISCC, a global biofuels certification body, told The Straits Times last year.

No questions asked

On a Saturday in mid-January, dozens of people arrive at the central square in the historic city of Melaka carrying plastic bottles of all shapes and sizes filled with cooking oil.

A banner above a stall advertises a public collection drive organised by Evergreen Oil & Feed, Malaysia’s largest supplier of UCO to Neste and a provider to other multinational fuel companies, including Repsol and Shell.

The idea is simple: individuals bring used cooking oil from home and receive 3 Malaysian ringgit per litre, the equivalent of about $0.65.

Among those bringing greasy containers that morning is an undercover reporter sent by SVT to put the system to the test. She carries a transparent plastic jerry can. Inside it is not waste oil from a kitchen, but fresh palm oil she had poured into the container earlier that day.

The journalist steps forward and hands the jerry can to a volunteer. Without asking any questions about the oil’s origin or contents, the volunteer places it on a scale and notes the weight. He then unscrews the cap and pours the liquid into a large plastic drum, mixing it with oil brought in by other members of the public.

Afterwards, the reporter walks to a nearby table where another volunteer asks her to fill out a simple form before receiving payment for the oil. She writes down a fake name and phone number. No verification is requested, and the cash changes hands.

The blue plastic drum is sealed and loaded onto the back of a truck, which will transport the batch to Evergreen Oil & Feed’s processing facility on the outskirts of Melaka. There, the oil will enter the industrial supply chain that feeds the global market for “waste-based” biofuels, including SAF.

Checks intended to catch fraud

Evergreen Oil & Feed did not reply to a request for comment on what happened at its UCO collection in January. In May 2025, the company’s owner CK Lau told The Straits Times that the firm follows the “proper processes” in its collection based on requirements established by International Sustainability and Carbon Certification (ISCC), the leading certification scheme recognised by the European Commission.

Carl Nyberg, senior vice president for renewable products at Neste, said in an interview with SVT that ensuring the traceability and integrity of the raw materials used in the production of green fuels is of utmost importance for the Finnish firm.

“If we receive concerns or hints that there are anomalies or suspicions around the raw materials we receive, we go in and investigate and then we stop the supplies from such suppliers,” he added.

After watching the footage of the oil collection in Melaka, Nyberg said Neste would “take this on board and dig a bit deeper” to understand the background. “Our objective is, of course, to ensure that we have suppliers that are behaving correctly, delivering the feedstocks that they have promised to deliver us, as we have in the contract,” he added.

A Neste spokesperson later added in a statement that each raw material shipment may undergo additional checks, including “advanced laboratory testing” performed at the company’s own facilities. “Based on the results of analyses on the raw materials we have received, we have not received raw material cargoes with typical profiles of crude palm oil,” they added.

Neste exports outweigh collection

As Neste’s largest provider of UCO in Malaysia, Evergreen Oil & Feed supplied the Finnish giant with more than 50,000 tonnes of the raw material – enough to fill 20 Olympic-sized swimming pools – in the first half of 2025, according to customs data obtained by SVT.

In total, Neste sourced around 250,000 tonnes of UCO from all the Malaysian traders it dealt with in 2024, the data showed.

However, only 100,000 tonnes of UCO are estimated to be collected annually in Malaysia, according to a 2024 analysis by consultancy Stratas Advisors for T&E. “Our suspicion is that not all of these volumes are legit waste oils, suggesting that some of them could be [virgin] palm oil,” said Simon Suzan, a data analyst at T&E.

Explainer: What is Sustainable Aviation Fuel (SAF)?

Under the current system, the entire SAF supply chain largely relies on a long paper trail rooted in self-declarations submitted by restaurants, factories and households providing the UCO, alongside sporadic inspections at the points where the raw material is collected.

In Europe, the verification of green fuel supply chains largely rests on certification systems like ISCC, which is led by the biofuels industry and, according to one source, enjoys “a kind of monopoly” in the sector. The body issues sustainability certificates to commodities traders and fuel suppliers.

ISCC says its certification process supports “sustainable, fully traceable, deforestation-free and climate-friendly supply chains”. But the certifier has come under frequent criticism from campaigners and researchers, who argue that its auditing system relies heavily on company-provided data and can struggle to detect fraud in complex global supply chains.

Watch the full Swedish documentary, “When can I fly green?”, on SVT Play

The problems in Malaysia are not isolated. A separate investigation by AFP and SourceMaterial recently found that Indonesian companies targeted in a palm oil fraud probe had supplied European firms including Neste and Eni.

In February, Indonesian police detained 11 people over suspicions that local companies had conspired with government officials to pass off palm oil as a waste byproduct called palm oil mill effluent (POME), including by offering bribes.

Neste said it had instructed its supplier to exclude the implicated Indonesian companies from its supply chain after the investigation became public. Analysis of periodic samples from shipments between 2023 and 2025 were “consistent with palm-derived waste”, not palm oil, it added. There is no suggestion that Neste had any knowledge of, or involvement in, the alleged Indonesian fraud.

EU ‘not happy’ about fraud risks

Neste turns the raw materials it buys from Southeast Asia and other regions into renewable fuels at its refineries in Singapore, the Netherlands and Finland.

Last year, the company sold nearly three-quarters of its renewable fuels, including SAF, in Europe, where green fuels are central to efforts to reduce the climate impact of aviation. The European Union, alongside the UK, introduced the world’s first SAF mandates in January 2025, requiring fuel suppliers to blend at least 2% SAF with conventional kerosene.

Anna-Kaisa Itkonen, EU spokesperson for climate and energy, said the European Commission is “of course not happy” about the risk of virgin palm oil contaminating the SAF supply chain.

“This was not the purpose when we started the policy and when we wanted to create this global wake-up call of greening aviation,” she added in an interview with SVT. “It undermines the policy because it is basically [de]frauding those who are complying with the rules.”

Itkonen said the European Commission is doing the best it can within its remit, but enforcement is up to individual member states. “We also have the possibility to make these rules more stringent and look into them and revise them,” she added.

Even if regulation is tightened, ensuring fraud-free SAF supplies will not be an easy task, industry insiders warn.

The former Neste director told Climate Home News that, with poor enforcement of the rules especially in source countries, complete control of the supply chain is practically impossible for companies handling enormous volumes of raw materials, like the Finnish firm.

“I don’t think anyone can say 100% putting their hand on a Bible,” the ex-employee added when asked whether Neste could confidently claim no virgin palm oil enters its SAF supply chain.

“The market needs a level playing field. If Neste rejects questionable supply, competitors will accept it. It’s a market-wide problem of fraudulent feedstocks.”

The post Top green jet fuel producer linked to suspect waste-oil supply chain appeared first on Climate Home News.

Top green jet fuel producer linked to suspect waste-oil supply chain

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