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https://science.sciencemag.org/content/371/6532/873 (subscription)
Plastics are a climate problem. Making precursors for common plastics, such as ethylene and carbon monoxide (CO), consumes fossil fuels and releases plenty of carbon dioxide (CO2). In recent years, chemists have devised bench-top reactors called electrochemical cells that aim to reverse the process, starting with water and waste CO2 from industrial processes and using renewable electricity to turn them into feedstocks for plastics. But that green vision has a practical problem: The cells often consume highly alkaline additives that themselves take energy to make.
“This has been a very challenging scientific problem,” says Peidong Yang, a chemist at the University of California, Berkeley. Now, his team and a second group are reporting strides toward solving the alkalinity hurdle. One advance links two electrochemical cells in tandem to bypass the problem altogether, and another turns to an enzymelike catalyst to generate a desired chemical without consuming alkaline additives. The plastics industry isn't about to abandon fossil fuels for CO2 and renewable electricity, but “the field is picking up steam,” says Feng Jiao, an electrochemist at the University of Delaware, Newark.
Companies currently make ethylene, a clear, sweet-smelling gas, by using superheated steam under pressure to “crack” the larger hydrocarbons in oil. Honed for decades, the process is extremely efficient, capable of producing ethylene for about $1000 per ton. But its production generates about 200 million tons of CO2 annually, 0.6% of the world's emissions.
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Electrochemical cells, which operate like batteries in reverse, offer a greener alternative. In contrast to batteries, which convert chemical energy into electricity, electrochemical cells feed electricity to catalysts that make chemicals.
I've toured a plant in France that had a big electrochemical cell for making caustic (sodium hydroxide) & chlorine gas by the electrolysis of salt water. Very energy intensive but that's old technology.
Plastics are a climate problem. Making precursors for common plastics, such as ethylene and carbon monoxide (CO), consumes fossil fuels and releases plenty of carbon dioxide (CO2). In recent years, chemists have devised bench-top reactors called electrochemical cells that aim to reverse the process, starting with water and waste CO2 from industrial processes and using renewable electricity to turn them into feedstocks for plastics. But that green vision has a practical problem: The cells often consume highly alkaline additives that themselves take energy to make.
“This has been a very challenging scientific problem,” says Peidong Yang, a chemist at the University of California, Berkeley. Now, his team and a second group are reporting strides toward solving the alkalinity hurdle. One advance links two electrochemical cells in tandem to bypass the problem altogether, and another turns to an enzymelike catalyst to generate a desired chemical without consuming alkaline additives. The plastics industry isn't about to abandon fossil fuels for CO2 and renewable electricity, but “the field is picking up steam,” says Feng Jiao, an electrochemist at the University of Delaware, Newark.
Companies currently make ethylene, a clear, sweet-smelling gas, by using superheated steam under pressure to “crack” the larger hydrocarbons in oil. Honed for decades, the process is extremely efficient, capable of producing ethylene for about $1000 per ton. But its production generates about 200 million tons of CO2 annually, 0.6% of the world's emissions.
=================================================================================================================
Electrochemical cells, which operate like batteries in reverse, offer a greener alternative. In contrast to batteries, which convert chemical energy into electricity, electrochemical cells feed electricity to catalysts that make chemicals.
I've toured a plant in France that had a big electrochemical cell for making caustic (sodium hydroxide) & chlorine gas by the electrolysis of salt water. Very energy intensive but that's old technology.