We know that real trees soak up carbon from the atmosphere — but fake trees?
A cheap plastic that removes carbon dioxide (CO2) from the atmosphere? “Yes,” says a team of chemists at the University of Southern California’s (USC) Loker Hydrocarbon Research Institute, led by Nobel Prize winner George Olah. Science Now reports on their work with an inexpensive polymer called polyethylenimine or PEI.
But how to maximize its absorption capabilities? Olah’s team dissolved the polymer in a solvent and spread it out, peanut-butter-style, on fumed silica — you know, like the stuff in those desiccant packets in your electronics packaging (“Do not eat,” by the way). It’s also used as a stabilizer for lipstick and other make-up.
Here are the geeky details from Science Now:
When the researchers tested the new material’s CO2-grabbing abilities, they found that in humid air—the kind present in most ambient conditions—each gram of the material sopped up an average of 1.72 nanomoles of CO2. That’s well above the 1.44 nanomoles per gram absorbed by a recent rival made from aminosilica and among the highest levels of CO2 absorption from air ever tested, the team reported last month in the Journal of the American Chemical Society. Once saturated with CO2, the PEI-silica combo is easy to regenerate. The CO2floats away after the polymer is heated to 85°C. Other commonly used solid CO2 absorbers must be heated to over 800°C to drive off the CO2.
Team member Surya Prakash says the polymer could also be used to make vast farms of artificial “trees” that could suck CO2 out of the atmosphere, much like real ones do. Prakash and Olah have been trying to stand the carbon paradigm on its ear for the past several years, exploring it as a positive rather than a negative for the planet. “People tend to think of CO2 as a problem rather than a resource,” he explained. “We want to take CO2, and instead of burying it underground, use it as a raw material, and convert it with alternative energy sources back to fuels and feedstocks.”
6 thoughts on “How Plastic Trees Could Help Pull Carbon Dioxide Out of the Air”
Are plastic trees more effective than real ones? Why not just plant real ones?
Ha! That’s an excellent question. One possible answer might be that real ones can take a long time to grow. But a related question might be: What’s the carbon footprint of making these things and transporting them to where they’d be “planted?”
Where does the comment “We want to take CO2, and instead of burying it underground, use it as a raw material…” lead? We need to take CO2 out of the atmosphere. We need to at least absorb the amounts we, as a planet, burn from fossil fuels. But in order to slow down global warming, we need to absorb more than we burn at some point. It would be great if we could get the atmosphere back to what would be considered “normal” levels. But just capturing it and releasing it again is not going to be helping. Is it?
Surely you folks know that REAL TREES remove CO2 from the atmosphere.
You all bring up great question that can be easily answered with a little research. Real trees do remove CO2 from the atmosphere, but do it at a rate much slower than PEI. Plus real trees require water and care (if grown at the farm level) which will require pumping water which is very energy intensive in CA. What they mean by capture and release is that the CO2 molecule captured in the PEI will be released in a controlled manner, captured and reused as a fuel, and this cycle can continue on indefinitly, which would make us carbon neutral. When they say ‘instead of stored underground’ they are referring to carbon sequestration, in which carbon is capture and stored indefinitly underground, for which we don’t know the long term ramifications of.
I reached Professor Surya Prakash at his USC office here in Los Angeles this morning to pose both these questions. True, “nature does a wonderful job recycling CO2” he says, but that effort also takes “nurture:” water, fertilizer and time to grow trees large enough to make a big difference. His idea of an artificial tree farm, while requiring energy to make it and move it where it needs to be, wouldn’t require any of those other three. He supports carbon-based products per se — think of his PEI material inside space suits and submarines and SCUBA gear, eating up CO2, or the advanced medical devices that used highly engineered plastics. But he’s working on simplifying what we use for energy. He and his colleague, George Olah, envision the elegance of a methanol economy, a simple liquid alcohol, and have spent more than a decade on the project in cahoots with the Jet Propulsion Lab in Pasadena, with funding from DARPA. “Keep It Simple, Stupid” Prakesh told me: harvest all that CO2 from the atmosphere, combine it with hydrogen stripped from water, and power the future.
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