Plastic is Forever
Those plastics people are forever clever. In headlines touting "DVDs and CD-ROMs that Thwart Global Warming", chemists describe "innovative ways of making polycarbonate plastics from CO2", which would yield "less expensive, safer and greener products". No mention of bisphenol A by these green inventors -- polycarbonate is a polyester of bisphenol A and carbonic acid.
Thomas E. Muller's research at CAT Catalytic Center, a collaboration of RWTH Aachen University, Bayer Material Science, and Bayer Technology led to the breakthrough. The Center was set up to leverage the expertise at the university, with that at Bayer, a prominent bisphenol-A manufacturer, in order to develop the new chemical processes and products. Muller presented his research at the American Chemical Society meeting this week and called the new process an "economic driving force". Dr Sakakura of the National Institute of Advanced Industrial Science and Technology in Tsukuba, Japan, also presented research on carbon dioxide fixation to synthesize polycarbonates, and said his process is cheaper then a previous one invented in Japan,and has the added benefit of circumventing the use of phosgene, a toxic gas, in the synthesis.
The two investigators did not divulge their processes because of pending patents. However several different methods for producing polycarbonate from CO2 have been described by others and can be found on freepatentsonline.com and patentstorm.com -- if you're curious about other processes. At MoleculeoftheDay.com, the author describes how to make polycarbonate using phosgene and a commenter offers that triphosgene can be substituted for phosgene.1
C02 Reduction: Little Building Blocks
One report notes that rock stars will be pleased to be contributing to carbon emissions reductions. Muller said that consumers may be "drinking from a carbon dioxide product and watching movies on waste-CO2 DVDs sooner than they think." "Millions of tons of polycarbonates already are sold each year with the volume rising", Mueller said, and "using CO2 to create polycarbonates might not solve the total carbon dioxide problem, but it could be a significant contribution."
While polycarbonate makes a nice drinking bottle, so do other materials. DVD's are pretty cheap with today's technology -- 100 blank DVDs for $30 is not too exorbitant. But who needs streaming video and audio if you can continue to purchase (and discard) cheap (bisphenol-A containing) plastic. However the DVD entire production process produces carbon emissions, much of which is not from the actual manufacture of the DVDs. For instance, News Corp published a carbon emissions analysis for the DVD release of the children's product, "Futurama, Bender's Big Score", which totals 447.5 tons of carbon for the DVD release. The site advertises their plan to make this a carbon neutral DVD, but you can get an idea of the carbon emissions breakdown.
Most of the carbon emissions used in producing such products don't come from manufacturing the DVD, and apparently manufacturing DVD's with this new method only sequesters nominal amounts of CO2. CBC News reported that despite Muller's enthusiasm, the scientist also acknowledged "that the sequestration would be "'in the per cent range'"(no number given), and only "a little building block"'.
Cement CO2 Sequestration
In other CO2 sequestration news, Nature reported that a UK researcher stumbled upon a process that occurs when cement breaks down at old building sites then becomes overgrown with weeds and plants. ("Waste concrete could help to lock up carbon":doi:10.1038/news.2008.732). Carbon dioxide is used by plants during photosynthesis then the plants release carbon containing root exudates. These exudates mix with calcium minerals from the cement to form calcium carbonate, thereby permanently removing CO2 from the atmosphere. The process could theoretically "lock up 4 million tonnes of carbon a year in the UK", reports Nature. The UK produces 150 tonnes of annual emissions. Another interesting little building block.
One commenter to that article noted that sequestration isn't as good as not emitting CO2 in the first place.
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1 Polycarbonate synthesis is not our field.
