This. The real question is, "Can CO2 be given more value by using it to make plastics than the value of the energy used to power the process?" This is a much

This. The real question is, "Can CO2 be given more value by using it to make plastics than the value of the energy used to power the process?" This is a much harder problem. A good start might be a thermodynamic analysis. Ethylene monomers have an enthalpy of formation from pure CO2 and H2O of 12.9 kWh/kg, plus losses due to process inefficiency. It's only 7.3 kWh/kg if you have a "free" source of hydrogen to provide the remaining energy, but typically industrial hydrogen comes from fossil fuels. Industrial electricity prices in the US and China are around 10c(=0.66 Yuan)/kWh, so that much electricity goes for about $1.30. But ethylene prices are only around $1.07/kg,[1] so from this admittedly simplistic analysis it would seem the answer is no, it's not worth it. This is before considering the extra energy required to concentrate CO2 from dilute form in the atmosphere or an exhaust flue. Someone else on this thread said it best -- the tree wins the technology contest. Self replicating, solar powered, soil building, carbon sequestering, water/air cleaning, etc. Oh yeah, and trees are literally[2] what makes it rain. [1] http://asia.nikkei.com/Markets/Commodities/Ethylene-prices-up-despite-cheaper-crude http://asia.nikkei.com/Markets/Commodities/Ethylene-prices-u... [2] By transpiring coastal rainfall, trees "kick it back up" and transport water to the inner parts of the continent like an irrigation system. Hence why deforestation leads to desertification. http://www.nature.com/nature/journal/v496/n7445/abs/nature11983.html http://www.nature.com/nature/journal/v496/n7445/abs/nature11...