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Hundreds of thousands of chemicals are manufactured by the chemical industry, which transforms raw materials – usually fossil fuels – into useful end products. Due to its size and its use of fossil fuel feedstocks, the chemical industry is responsible for roughly 6% of global carbon emissions.

But researchers, led by the University of Cambridge, are developing new methods that could one day lead to the ‘de-fossilisation’ of this important sector.

They have developed a hybrid device that combines light-harvesting organic polymers with bacterial enzymes to convert sunlight, water and carbon dioxide into formate, a fuel that can drive further chemical transformations.

Their ‘semi-artificial leaf’ mimics photosynthesis: the process plants use to convert sunlight into energy, and does not require any external power source. Unlike earlier prototypes, which often relied on toxic or unstable light absorbers, the new biohybrid design avoids toxic semiconductors, lasts longer, and can run without additional chemicals that previously hindered efficiency.

In tests, the researchers used sunlight to convert carbon dioxide into formate and then used it directly in a ‘domino’ chemical reaction to produce an important type of compound used in pharmaceuticals, with high yield and purity.

Their results, reported in the journal Joule, mark the first time that organic semiconductors have been used as the light-harvesting component in this type of biohybrid device, opening the door to a new family of sustainable artificial leaves.

The chemical industry is central to the world economy, producing products from pharmaceuticals and fertilisers, to plastics, paints, electronics, cleaning products, and toiletries.

“If we’re going to build a circular, sustainable economy, the chemical industry is a big, complex problem that we must address,” said Professor Erwin Reisner from Cambridge’s Yusuf Hamied Department of Chemistry, who led the research. “We’ve got to come up with ways to de-fossilise this important sector, which produces so many important products we all need. It’s a huge opportunity if we can get it right.”

Reisner’s research group specialises in the development of artificial leaves, which turn sunlight into carbon-based fuels and chemicals without relying on fossil fuels. But many of their earlier designs depend on synthetic catalysts or inorganic semiconductors, which either degrade quickly, waste much of the solar spectrum, or contain toxic elements such as lead.

“If we can remove the toxic components and start using organic elements, we end up with a clean chemical reaction and a single end product, without any unwanted side reactions,” said co-first author Dr Celine Yeung, who completed the research as part of her PhD work in Reisner’s lab. “This device combines the best of both worlds – organic semiconductors are tuneable and non-toxic, while biocatalysts are highly selective and efficient.”

The new device integrates organic semiconductors with enzymes from sulphate-reducing bacteria, splitting water into hydrogen and oxygen or converting carbon dioxide into formate.

The researchers have also addressed a long-standing challenge: most systems require chemical additives, known as buffers, to keep the enzymes running. These can break down quickly and limit stability. By embedding a helper enzyme, carbonic anhydrase, into a porous titania structure, the researchers enabled the system to work in a simple bicarbonate solution — similar to sparkling water — without unsustainable additives.

“It’s like a big puzzle,” said co-first author Dr Yongpeng Liu, a postdoctoral researcher in Reisner’s lab. “We have all these different components that we’ve been trying to bring together for a single purpose. It took us a long time to figure out how this specific enzyme is immobilised on an electrode, but we’re now starting to see the fruits from these efforts.”

“By really studying how the enzyme works, we were able to precisely design the materials that make up the different layers of our sandwich-like device,” said Yeung. “This design made the parts work together more effectively, from the tiny nanoscale up to the full artificial leaf.”

Tests showed the artificial leaf produced high currents and achieved near-perfect efficiency in directing electrons into fuel-making reactions. The device successfully ran for over 24 hours: more than twice as long as previous designs.

The researchers are hoping to further develop their designs to extend the lifespan of the device and adapt it so it can produce different types of chemical products.

“We’ve shown it’s possible to create solar-powered devices that are not only efficient and durable but also free from toxic or unsustainable components,” said Reisner. “This could be a fundamental platform for producing green fuels and chemicals in future – it’s a real opportunity to do some exciting and important chemistry.”

The research was supported in part by the Singapore Agency for Science, Technology and Research (A*STAR), the European Research Council, the Swiss National Science Foundation, the Royal Academy of Engineering, and UK Research and Innovation (UKRI). Erwin Reisner is a Fellow of St John’s College, Cambridge. Celine Yeung is a Member of Downing College, Cambridge.
 

Reference:
Celine Wing See Yeung et al. ‘Semi-artificial leaf interfacing organic semiconductors and enzymes for solar chemical synthesis.’ Joule (2025). DOI: 10.1016/j.joule.2025.102165

Researchers have demonstrated a new and sustainable way to make the chemicals that are the basis of thousands of products – from plastics to cosmetics – we use every day.

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By 2040, the energy demands of the tech industry could be up to 25 times higher than today, with unchecked growth of data centres driven by AI expected to create surges in electricity consumption that will strain power grids and accelerate carbon emissions.  

This is according to a new report from the University of Cambridge’s Minderoo Centre for Technology and Democracy, which suggests that even the most conservative estimate for big tech’s energy needs will see a five-fold increase over the next 15 years. 

The idea that governments such as the UK can become leaders in AI while simultaneously meeting their net zero targets amounts to “magical thinking at the highest levels,” according to the report’s authors. The UK is committed to net zero greenhouse gas emissions by 2050.

Researchers call for global standards in reporting AI’s environmental cost through forums such as COP, the UN climate summit, and argue that the UK should advocate for this on the international stage while ensuring democratic oversight at home.

The report, published today, synthesises projections from leading consultancies to forecast the energy demands of the global tech industry. The researchers note that these projections are based on claims by tech firms themselves. 

At the moment, data centres – the facilities that house servers for processing and storing data, along with cooling systems preventing this hardware from overheating – account for nearly 1.5% of global emissions.

This figure is expected to grow by 15-30% each year to reach 8% of total global greenhouse gas emissions by 2040, write the report’s authors. They point out that this would far exceed current emissions from air travel. 

The report highlights that in the US, China, and Europe, data centres already consume around 2-4% of national electricity, with regional concentrations becoming extreme. For example, up to 20% of all power in Ireland now goes to data centres in Dublin’s cluster.

“We know the environmental impact of AI will be formidable, but tech giants are deliberately vague about the energy requirements implicit in their aims,” said Bhargav Srinivasa Desikan, the report’s lead author from Cambridge’s Minderoo Centre.

“The lack of hard data on electricity and water consumption as well as associated carbon emissions of digital technology leaves policymakers and researchers in the dark about the climate harms AI might cause.”

“We need to see urgent action from governments to prevent AI from derailing climate goals, not just deferring to tech companies on the promise of economic growth,” said Desikan.

The researchers also use data from corporate press releases and ESG reports of some of the world’s tech giants to show the alarming trajectory of energy use before the AI race had fully kicked into gear.

Google’s reported greenhouse gas emissions rose by 48% between 2019 and 2023, while Microsoft’s reported emissions increased by nearly 30% from 2020 to 2023. Amazon’s carbon footprint grew around 40% between 2019 and 2021, and – while it has begun to fall – remains well above 2019 levels.

This self-reported data is contested, note the researchers, and some independent reporting suggests that actual emissions from tech companies are much higher.  

Several tech giants are looking to nuclear power to defuse the energy timebomb at the heart of their ambitions. Sam Altman, CEO of OpenAI, has argued that fusion is needed to meet AI’s potential, while Meta have said that nuclear energy can “provide firm, baseload power” to supply their data centres.

Microsoft have even signed a 20-year agreement to reactivate the Three Mile Island plant – site of the worst nuclear accident in US history.

Some tech leaders, such as former Google CEO Eric Schmidt, argue that environmental costs of AI will be offset by its benefits for the climate crisis – from contributing to scientific breakthroughs in green energy to enhanced climate change modelling.

“Despite the rapacious energy demands of AI, tech companies encourage governments to see these technologies as accelerators for the green transition,” said Prof Gina Neff, Executive Director of the Minderoo Centre for Technology and Democracy.

“These claims appeal to governments banking on AI to grow the economy, but they may compromise society's climate commitments.”

“Big Tech is blowing past their own climate goals, while they rely heavily on renewable energy certificates and carbon offsets rather than reducing their emissions,” said Prof Neff.

“Generative AI may be helpful for designing climate solutions, but there is a real risk that emissions from the AI build-out will outstrip any climate gains as tech companies abandon net zero goals and pursue huge AI-driven profits.”

The report calls for the UK’s environmental policies to be updated for the “AI era”. Recommendations include adding AI’s energy footprint into national decarbonisation plans, with specific carbon reduction targets for data centres and AI services, and requirements for detailed reporting of energy and water consumption.  

Ofgem should set strict energy efficiency targets for data centres, write the report’s authors, while the Department for Energy Security and Net Zero and the Department for Science, Innovation and Technology should tie AI research funding and data centre operations to clean power adoption.

The report’s authors note that that UK’s new AI Energy Council currently consists entirely of energy bodies and tech companies – with no representation for communities, climate groups or civil society.  

“Energy grids are already stretched,” said Prof John Naughton, Chair of the Advisory Board at the Minderoo Centre for Technology and Democracy.

“Every megawatt allocated to AI data centres will be a megawatt unavailable for housing or manufacturing. Governments need to be straight with the public about the inevitable energy trade-offs that will come with doubling down on AI as an engine of economic growth.”
 

With countries such as the UK declaring ambitious goals for both AI leadership and decarbonisation, a new report suggests that AI could drive a 25-fold increase in the global tech sector’s energy use by 2040.

The text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright ©University of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.