Eco-fuels produced with greenhouse gases and plastic waste, using only solar energy? It sounds like a dream: two of the greatest threats to life on Earth are eliminated and green fuel is created using clean energy. All without emitting a gram of CO2. It is the idea of a group of chemists from theUniversity of Cambridgewho developed a “reactor” capable of taking energy from the sun and use it to transform carbon dioxide and the more common plastics produced by man, in chemical components useful in the industrial field, from cosmetics to automotive.
In the tests presented on Nature Synthesisthe CO2 has been converted to syngasconsidered the fundamental building block from which the main ones can then be obtained sustainable liquid fuels. Not only that: another test was conducted by obtaining glycolic acidan element widely used in cosmetics, starting from the common polyethylene terephthalate (Pet) bottles.
“The strong point of this system is undoubtedly its versatility – he explains Subhajit Bhattacharjee, researcher at the Cambridge chemistry department and first author of the work – . For now we have managed to generate very simple carbon-based molecules, but with a little development we can arrive at much more complex compounds.”
Recycling in the sunlight: the chemical mechanism
That of Bhattacharjee and colleagues is not the only project that allows to recycle CO2 or plastic and give it new life, but it is undoubtedly the first to do it in a completely green way, obtaining energy from the photons of the Sun. “In general, converting CO2 it is a very energy-intensive and expensive process – observes Bhattacharjee – . Our system only needs to be illuminated, and immediately begins to transform elements harmful to the environment into new raw material”.
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To convert light into energy, similar to what happens with photovoltaic panels, the reactor uses an “absorber” in perovskitea mineral composed of calcium titanateconsidered today the most efficient alternative to the silicon for the photovoltaic cells of the future. The real transformation then takes place inside, with the help of a catalyst. The scientists designed the device intelligently, so as to allow the final product to be obtained selectively, starting from the catalyst used. The process is known as photo/electro-catalytic conversion of CO2 and some plastic. Glycolic acid e syngas to date the “secondary materials” obtained, “but our reactor is flexible: it will be possible to obtain a wide range of other compounds of high value in an efficient way”, write the experts in the conclusions of the work.
“Solar recycling plants in the future”
Every year, according to data from United Nations Environment Programme, around 300 million tons of plastic are produced and discarded. To give a better idea, it is approximately the weight of the entire human population: all the more than 8 billion individuals alive today. Of this huge amount of waste, only 9% is recycled and re-enters the value chain; the rest goes to landfill or, worse, ends up in the sea in large pieces or in the form of microplastics.
“Developing the circular economy, a model in which we create value and put useful products back on the market, starting from waste that would instead be directed to who knows what landfill is vital for tackling the great ecological and climate challenge we face”, underlines Erwin Reisnerprofessor of Energy and Sustainability at Cambridge, senior author of the study who led the team of young researchers. Reisner is among the world’s leading experts in solar-powered plastic recycling technologies, so much so that his project has received funding from the European Union and the European Research Council. “This idea could allow us in the future to develop a waste treatment and recycling plant completely powered by the energy of the Sun”, conclude the British scientists.