̽��ֱ�� of Cambridge - Motiar Rahaman

Clean, sustainable fuels made ‘from thin air’ and plastic waste

sc604 — Mon, 19 Jun 2023 15:15:53 +0000

̽��ֱ��researchers, from the ̽��ֱ�� of Cambridge, developed a solar-powered reactor that converts captured CO2 and plastic waste into sustainable fuels and other valuable chemical products. In tests, CO2 was converted into syngas, a key building block for sustainable liquid fuels, and plastic bottles were converted into glycolic acid, which is widely used in the cosmetics industry.

Unlike earlier tests of their solar fuels technology however, the team took CO2 from real-world sources – such as industrial exhaust or the air itself. ̽��ֱ��researchers were able to capture and concentrate the CO2 and convert it into sustainable fuel.

Although improvements are needed before this technology can be used at an industrial scale, the results, reported in the journal Joule, represent another important step toward the production of clean fuels to power the economy, without the need for environmentally destructive oil and gas extraction.

For several years, Professor Erwin Reisner’s research group, based in the Yusuf Hamied Department of Chemistry, has been developing sustainable, net-zero carbon fuels inspired by photosynthesis – the process by which plants convert sunlight into food – using artificial leaves. These artificial leaves convert CO2 and water into fuels using just the power of the sun.

To date, their solar-driven experiments have used pure, concentrated CO2 from a cylinder, but for the technology to be of practical use, it needs to be able to actively capture CO2 from industrial processes, or directly from the air. However, since CO2 is just one of many types of molecules in the air we breathe, making this technology selective enough to convert highly diluted CO2 is a huge technical challenge.

“We’re not just interested in decarbonisation, but de-fossilisation – we need to completely eliminate fossil fuels in order to create a truly circular economy,” said Reisner. “In the medium term, this technology could help reduce carbon emissions by capturing them from industry and turning them into something useful, but ultimately, we need to cut fossil fuels out of the equation entirely and capture CO2 from the air.”

̽��ֱ��researchers took their inspiration from carbon capture and storage (CCS), where CO2 is captured and then pumped and stored underground.

“CCS is a technology that’s popular with the fossil fuel industry as a way to reduce carbon emissions while continuing oil and gas exploration,” said Reisner. “But if instead of carbon capture and storage, we had carbon capture and utilisation, we could make something useful from CO2 instead of burying it underground, with unknown long-term consequences, and eliminate the use of fossil fuels.”

̽��ֱ��researchers adapted their solar-driven technology so that it works with flue gas or directly from the air, converting CO2 and plastics into fuel and chemicals using only the power of the sun.

By bubbling air through the system containing an alkaline solution, the CO2 selectively gets trapped, and the other gases present in air, such as nitrogen and oxygen, harmlessly bubble out. This bubbling process allows the researchers to concentrate the CO2 from air in solution, making it easier to work with.

̽��ֱ��integrated system contains a photocathode and an anode. ̽��ֱ��system has two compartments: on one side is captured CO2 solution that gets converted into syngas, a simple fuel. On the other plastics are converted into useful chemicals using only sunlight.

“ ̽��ֱ��plastic component is an important trick to this system,” said co-first author Dr Motiar Rahaman. “Capturing and using CO2 from the air makes the chemistry more difficult. But, if we add plastic waste to the system, the plastic donates electrons to the CO2. ̽��ֱ��plastic breaks down to glycolic acid, which is widely used in the cosmetics industry, and the CO2 is converted into syngas, which is a simple fuel.”

“This solar-powered system takes two harmful waste products – plastic and carbon emissions – and converts them into something truly useful,” said co-first author Dr Sayan Kar.

“Instead of storing CO2 underground, like in CCS, we can capture it from the air and make clean fuel from it,” said Rahaman. “This way, we can cut out the fossil fuel industry from the process of fuel production, which can hopefully help us avoid climate destruction.”

“ ̽��ֱ��fact that we can effectively take CO2 from air and make something useful from it is special,” said Kar. “It’s satisfying to see that we can actually do it using only sunlight.”

̽��ֱ��scientists are currently working on a bench-top demonstrator device with improved efficiency and practicality to highlight the benefits of coupling direct air capture with CO2 utilisation as a path to a zero-carbon future.

̽��ֱ��research was supported in part by the Weizmann Institute of Science, the European Commission Marie Skłodowska-Curie Fellowship, the Winton Programme for the Physics of Sustainability, and the Engineering and Physical Sciences Research Council (EPSRC), part of UK Research and Innovation (UKRI). Erwin Reisner is a Fellow and Motiar Rahaman is a Research Associate of St John’s College, Cambridge. Erwin Reisner leads the Cambridge Circular Plastics Centre (CirPlas), which aims to eliminate plastic waste by combining blue-sky thinking with practical measures.

Reference:
Sayan Kar, Motiar Rahaman et al. ‘Integrated Capture and Solar-driven Utilization of CO2 from Flue Gas and Air.’ Joule (2023). DOI: 10.1016/j.joule.2023.05.022

For more information on energy-related research in Cambridge, please visit Energy IRC, which brings together Cambridge’s research knowledge and expertise, in collaboration with global partners, to create solutions for a sustainable and resilient energy landscape for generations to come.

Researchers have demonstrated how carbon dioxide can be captured from industrial processes – or even directly from the air – and transformed into clean, sustainable fuels using just the energy from the sun.

We’re not just interested in decarbonisation, but de-fossilisation – we need to completely eliminate fossil fuels in order to create a truly circular economy

Erwin Reisner

Ariffin Mohamad Annuar

Carbon capture from air and its photoelectrochemical conversion into fuel with simultaneous waste plastic conversion into chemicals.

̽��ֱ��text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, 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.

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Driving on sunshine: clean, usable liquid fuels made from solar power

sc604 — Thu, 18 May 2023 15:01:02 +0000

̽��ֱ��researchers, from the ̽��ֱ�� of Cambridge, harnessed the power of photosynthesis to convert CO2, water and sunlight into multicarbon fuels – ethanol and propanol – in a single step. These fuels have a high energy density and can be easily stored or transported.

Unlike fossil fuels, these solar fuels produce net-zero carbon emissions and are completely renewable, and unlike most bioethanol, they do not divert any agricultural land away from food production.

While the technology is still at laboratory scale, the researchers say their ‘artificial leaves’ are an important step in the transition away from a fossil fuel-based economy. ̽��ֱ��results are reported in the journal Nature Energy.

Bioethanol is touted as a cleaner alternative to petrol, since it is made from plants instead of fossil fuels. Most cars and trucks on the road today run on petrol containing up to 10% ethanol (E10 fuel). ̽��ֱ��United States is the world’s largest bioethanol producer: according to the U.S. Department of Agriculture, almost 45% of all corn grown in the US is used for ethanol production.

“Biofuels like ethanol are a controversial technology, not least because they take up agricultural land that could be used to grow food instead,” said Professor Erwin Reisner, who led the research.

For several years, Reisner’s research group, based in the Yusuf Hamied Department of Chemistry, has been developing sustainable, zero-carbon fuels inspired by photosynthesis – the process by which plants convert sunlight into food – using artificial leaves.

To date, these artificial leaves have only been able to make simple chemicals, such as syngas, a mixture of hydrogen and carbon monoxide that is used to produce fuels, pharmaceuticals, plastics and fertilisers. But to make the technology more practical, it would need to be able to produce more complex chemicals directly in a single solar-powered step.

Now, the artificial leaf can directly produce clean ethanol and propanol without the need for the intermediary step of producing syngas.

̽��ֱ��researchers developed a copper and palladium-based catalyst. ̽��ֱ��catalyst was optimised in a way that allowed the artificial leaf to produce more complex chemicals, specifically the multicarbon alcohols ethanol and n-propanol. Both alcohols are high energy density fuels that can be easily transported and stored.

Other scientists have been able to produce similar chemicals using electrical power, but this is the first time that such complex chemicals have been produced with an artificial leaf using only the energy from the Sun.

“Shining sunlight on the artificial leaves and getting liquid fuel from carbon dioxide and water is an amazing bit of chemistry,” said Dr Motiar Rahaman, the paper’s first author. “Normally, when you try to convert CO2 into another chemical product using an artificial leaf device, you almost always get carbon monoxide or syngas, but here, we’ve been able to produce a practical liquid fuel just using the power of the Sun. It’s an exciting advance that opens up whole new avenues in our work.”

At present, the device is a proof of concept and shows only modest efficiency. ̽��ֱ��researchers are working to optimise the light absorbers so that they can better absorb sunlight and optimising the catalyst so it can convert more sunlight into fuel. Further work will also be required to make the device scalable so that it can produce large volumes of fuel.

“Even though there’s still work to be done, we’ve shown what these artificial leaves are capable of doing,” said Reisner. “It’s important to show that we can go beyond the simplest molecules and make things that are directly useful as we transition away from fossil fuels.”

̽��ֱ��research was supported in part by the European Commission Marie Skłodowska-Curie Fellowship, the Cambridge Trust, and the Winton Programme for the Physics of Sustainability. Erwin Reisner is a Fellow and Motiar Rahaman is a Research Associate of St John’s College, Cambridge.

Reference:
Motiar Rahaman et al. ‘Solar-driven liquid multi-carbon fuel production using a standalone perovskite-BiVO4 artificial leaf.’ Nature Energy (2023). DOI: 10.1038/s41560-023-01262-3

Researchers have developed a solar-powered technology that converts carbon dioxide and water into liquid fuels that can be added directly to a car’s engine as drop-in fuel.

Shining sunlight on the artificial leaves and getting liquid fuel from carbon dioxide and water is an amazing bit of chemistry

Motiar Rahaman

A photoreactor with an artificial leaf working under solar irradiation.

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Solar-powered system converts plastic and greenhouse gases into sustainable fuels

sc604 — Mon, 09 Jan 2023 16:00:00 +0000

̽��ֱ��researchers, from the ̽��ֱ�� of Cambridge, developed the system, which can convert two waste streams into two chemical products at the same time – the first time this has been achieved in a solar-powered reactor.

̽��ֱ��reactor converts carbon dioxide (CO2) and plastics into different products that are useful in a range of industries. In tests, CO2 was converted into syngas, a key building block for sustainable liquid fuels, and plastic bottles were converted into glycolic acid, which is widely used in the cosmetics industry. ̽��ֱ��system can easily be tuned to produce different products by changing the type of catalyst used in the reactor.

Converting plastics and greenhouse gases – two of the biggest threats facing the natural world – into useful and valuable products using solar energy is an important step in the transition to a more sustainable, circular economy. ̽��ֱ��results are reported in the journal Nature Synthesis.

“Converting waste into something useful using solar energy is a major goal of our research,” said Professor Erwin Reisner from the Yusuf Hamied Department of Chemistry, the paper’s senior author. “Plastic pollution is a huge problem worldwide, and often, many of the plastics we throw into recycling bins are incinerated or end up in landfill.”

Reisner also leads the Cambridge Circular Plastics Centre (CirPlas), which aims to eliminate plastic waste by combining blue-sky thinking with practical measures.

Other solar-powered ‘recycling’ technologies hold promise for addressing plastic pollution and for reducing the amount of greenhouse gases in the atmosphere, but to date, they have not been combined in a single process.

“A solar-driven technology that could help to address plastic pollution and greenhouse gases at the same time could be a game-changer in the development of a circular economy,” said Subhajit Bhattacharjee, the paper’s co-first author.

“We also need something that’s tuneable, so that you can easily make changes depending on the final product you want,” said co-first author Dr Motiar Rahaman.

̽��ֱ��researchers developed an integrated reactor with two separate compartments: one for plastic, and one for greenhouse gases. ̽��ֱ��reactor uses a light absorber based on perovskite – a promising alternative to silicon for next-generation solar cells.

̽��ֱ��team designed different catalysts, which were integrated into the light absorber. By changing the catalyst, the researchers could then change the end product. Tests of the reactor under normal temperature and pressure conditions showed that the reactor could efficiently convert PET plastic bottles and CO2 into different carbon-based fuels such as CO, syngas or formate, in addition to glycolic acid. ̽��ֱ��Cambridge-developed reactor produced these products at a rate that is also much higher than conventional photocatalytic CO2 reduction processes.

“Generally, CO2 conversion requires a lot of energy, but with our system, basically you just shine a light at it, and it starts converting harmful products into something useful and sustainable,” said Rahaman. “Prior to this system, we didn’t have anything that could make high-value products selectively and efficiently.”

“What’s so special about this system is the versatility and tuneability – we’re making fairly simple carbon-based molecules right now, but in future, we could be able to tune the system to make far more complex products, just by changing the catalyst,” said Bhattacharjee.

Reisner recently received new funding from the European Research Council to help the development of their solar-powered reactor. Over the next five years, they hope to further develop the reactor to produce more complex molecules. ̽��ֱ��researchers say that similar techniques could someday be used to develop an entirely solar-powered recycling plant.

“Developing a circular economy, where we make useful things from waste instead of throwing it into landfill, is vital if we’re going to meaningfully address the climate crisis and protect the natural world,” said Reisner. “And powering these solutions using the Sun means that we’re doing it cleanly and sustainably.”

̽��ֱ��research was supported in part by the European Union, the European Research Council, the Cambridge Trust, Hermann and Marianne Straniak Stiftung, and the Engineering and Physical Sciences Research Council (EPSRC), part of UK Research and Innovation (UKRI). Erwin Reisner is a Fellow of St John’s College, Cambridge.

Reference:
Subhajit Bhattacharjee, Motiar Rahaman et al. ‘Photoelectrochemical CO2-to-fuel conversion with simultaneous plastic reforming.’ Nature Synthesis (2023). DOI: 10.1038/s44160-022-00196-0

Researchers have developed a system that can transform plastic waste and greenhouse gases into sustainable fuels and other valuable products – using just the energy from the Sun.

A solar-driven technology that could help to address plastic pollution and greenhouse gases at the same time could be a game-changer in the development of a circular economy

Subhajit Bhattacharjee

Reisner Lab

Solar-powered reactor for converting plastic and greenhouse gases into sustainable fuels

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, 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.

Yes