Chemists can now in theory turn carbon dioxide back into coal and light and heat homes with transparent wood. The world has ample energy-saving ideas.
Australian scientists have found a way to take carbon dioxide and turn it back into something like coal.
It is as if they had translated the hundred-million-year process of making fossil fuel – a natural process powered in the Carboniferous Era by immense amounts of time, massive pressures and huge temperatures – in a laboratory in a day.
They used liquid metal catalysts – a catalyst is a compound that can midwife chemical change without itself being changed – to convert a solution of carbon dioxide into solid flakes of carbon.
And in a second reminder of the high levels of ingenuity and invention at work in the world’s laboratories, as chemists, physicists, biologists and engineers confront the twin challenges of climate change and efficient use of renewable energy, Swedish scientists report that they know how to make timber transparent and heat-storing. That is, they have a way of fashioning wood that can transmit light, and at the same time insulate the building it illuminates.
It may be some time before any huge-scale investment finds a way of taking the greenhouse gas from the air to convert it to solid carbon that can then be buried: for the moment, the surest way of soaking up the emissions from car exhausts and power station chimneys is to restore and protect forests.
“We’ve shown it’s possible to turn the gas back into carbon at room temperature, in a process that’s efficient and scalable”
But researchers from Melbourne and Sydney report in the journal Nature Communications that they developed a liquid-metal electrocatalyst that transforms gaseous CO2 directly into carbon-containing solids at room temperature.
They charged their cerium-oxide and liquid gallium catalyst with an electric current and introduced it to a beaker of carbon dioxide dissolved in an electrolyte liquid, to collect solid flakes of carbon, of a quality good enough to be used, they say, to make high performance capacitor electrodes.
“While we can’t literally turn back time, turning carbon dioxide and burying it back in the ground is a bit like rewinding the emissions clock,” said Torben Daeneke of the Royal Melbourne Institute of Technology, known as RMIT Melbourne.
“To date, CO2 has only been converted into a solid at extremely high temperatures, making it industrially unviable. By using liquid metals as a catalyst, we’ve shown it’s possible to turn the gas back into carbon at room temperature, in a process that’s efficient and scalable.”
Hard to accomplish
This would be a first step in safely storing what had once been the atmospheric carbon dioxide that – thanks to humankind’s profligate use of fossil fuels for 200 years – drives global warming and potentially catastrophic climate change. Researchers have been wrestling with the idea of carbon capture technology for years.
They have also been pointing out, for years, that the carbon dioxide from power station emissions could be captured and recycled as the basis for the organic chemical industry, or even for fuel..
None of the technologies explored so far is nearing commercial or large-scale production. But researchers go on trying to find new ways to save energy by making the most of natural materials.
Three years ago Lars Berglund of the Royal Institute of Technology in Stockholm announced an optically transparent wood. He and colleagues took out the light-absorbing lignin from some balsa wood, treated it with acrylic and ended up with timber fabric that they could see through, somewhat hazily, but strong enough to bear a load.
And, his research colleague told a meeting of the American Chemical Society in Orlando, Florida in April, it can now do more. It can absorb and release heat, and it could even be made biodegradable.
It could be the fabric of a new generation of eco-friendly housing, with the addition of polyethylene glycol or PEG, a wood-friendly polymer that melts in the warmth, absorbing heat – but at night solidifies again, releasing heat. In effect, the timber becomes a solar battery.
“Back in 2016, we showed that transparent wood has excellent thermal-insulating properties compared with glass, combined with high optical transmittance. In this work, we tried to reduce the building energy consumption even more by incorporating a material that can absorb, store and release heat,” said Céline Montanari of the Stockholm institute.
“During a sunny day the material will absorb heat before it reaches the indoor space, and the indoors will be cooler than the outside. And at night, the reverse occurs – the PEG becomes solid and releases heat indoors so you can maintain a constant temperature in the house.”
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