EuroWire May 2020

Transatlantic cable

when heated. Metal-organic frameworks (MOFs) proved the most promising because they could store a large amount of water and, so, take away more heat when heated. “Previously, researchers have tried to use MOFs to extract water from the desert air,” Mr Wang said, “but MOFs are still really expensive, so large-scale application isn’t really practical. Our study shows electronics cooling is a good real-life application of MOFs. We used less than 0.3g of material in our experiment, and the cooling e ect it produced was signi cant.” For the experiment, the team selected a type of MOF called MIL-101(Cr) because of its water-absorbing capacity and its high sensitivity to temperature changes. Three 16cm 2 aluminium sheets were coated with di erent thicknesses of MIL-101(Cr) – 198µm, 313µm and 516µm – and subjected to heating. The MIL-101(Cr) coating delayed the temperature rise of the sheets, with the e ect increasing in line with the coating thickness. While an uncoated sheet took 5.2 minutes to reach 60°C, the thinnest coating doubled this time, so that it took 11.7 minutes for a sheet to reach 60°C. For the sheet with the thickest coating, it took 19.35 minutes of heating to reach 60°C. “In addition to e ective cooling, MIL-101(Cr) can quickly recover by absorbing moisture again, once the heat source is removed, just like how mammals rehydrate and [are] ready to sweat again,” Mr Wang said. “So this method is really suitable for devices that aren’t running all the time, like phones, charging batteries and telecommunications base stations, which can get overloaded sometimes.” To investigate the cooling e ect of MIL-101(Cr) on actual devices, Mr Wang’s team tested a coated heat sink on a micro- computing device. Compared to an uncoated heat sink, the coated heat sink reduced the chip temperature by up to 7°C when the device was run at heavy workloads for 15 minutes. Researchers plan to improve the material’s thermal conductivity. First author Chenxi Wang said, “Once all the water is gone, the dried coating will become a resistance that a ects devices’ heat dissipation,” so research will be expanded into incorporating thermal conductive additives, such as graphene, into the material to help address the problem. For MOFs to be used in mobile phones, however, the costs will need to fall considerably, but “by nding MOFs a practical application we hope to increase the market demand for them, and encourage more research on MOFs to bring down the costs.”

Aerospace

UK Sustainable Aviation coalition backs government target

Members of the UK Sustainable Aviation coalition have given their backing to the UK government’s commitment to achieve net zero carbon emissions by 2050. The move follows the publication of the Sustainable Aviation review, “Decarbonisation road-map: a path to net zero”, which explains how reductions could be made by using a range of measures that include smarter ight operations, new aircraft and engine technology, modernising UK airspace, the use of sustainable aviation fuels, and market-based policy measures. Sustainable Aviation members believe the UK could still grow its passenger numbers by the forecast 70 per cent, while reducing net emissions to zero (from the current 30 million tonnes of CO 2 per year). Its “Sustainable aviation fuels road-map” was released at the same time as the Decarbonisation road map, identifying the speci c role that sustainable aviation fuels could play in meeting the zero commitment. It forecasts that the UK could be a world leader in the development of sustainable aviation fuels, meeting 32 per cent of the nation’s demand for aviation fuel by 2050. Neil Robinson, chair of Sustainable Aviation, said, “Climate change is a clear and pressing issue for people, businesses, and governments across the world. We know aviation emissions will increase if decisive action is not taken, and that’s why UK aviation [is committed] to achieving net zero carbon emissions by 2050 through an international approach, working with governments around the world and through the UN. “The UK is well positioned to become one of the leaders in the green technologies of the future, including sustainable aviation fuels and electric ight, creating highly skilled and well paid jobs in the process, and we look forward to working in partnership with ministers to help realise these opportunities.” Responding, the UK secretary of state for transport Grant Shapps said, “The ght against climate change is one of the greatest challenges facing the modern world, but the aviation sector’s commitment is a huge step forward in creating a greener future. Aviation has a crucial role to play in reducing carbon emissions, and with the help of new technologies, renewable fuels, and our continued international cooperation through the UN agency, the International Civil Aviation Organisation, we’ll be able to strike that balance, creating a greener and cleaner future.”

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May 2020