No sooner do the Friends of Earth highlight how the production of nanomaterials probably consumes more energy than it saves, than research at MIT has demonstrated a method for producing carbon nanotubes that reduces emissions of harmful byproducts at least ten-fold and up to a factor of 100 and cuts the amount of energy used in half.The research, which was initially published in the American Chemical Society’s journal ACS Nano, has provided a relatively simple way of reducing the byproducts that come from the catalytic chemical vapor disposition (CCVD) method for making multi-walled nanotubes.
Multi-walled carbon nanotubes (MWNTs) have undergone a huge expansion in capacity over the last three years with one producer, Bayer Material Science, having added nearly 600% more capacity this year from its 2007 levels. Bayer was not alone. Nanocyl and Arkema have been in a capacity race along with Bayer over these last three years, matching nearly every capacity increase.
This may drop the price of MWNTs considerably (by some estimates as much as half over the last five years), but it also is not very eco-friendly. CCVD is estimated to release 97% of its initial feedstock into the air as unreacted compounds, and we’re talking real harmful stuff like benzene.
In coverage of this research over at the AIChE blog, one of the lead authors of the MIT research, Desiree Plata, explains how they replaced the process of heating carbon-based gases and instead added key reactive ingredients into the process to eliminate many of the harmful byproducts. Now it may take some time for this get into the industrial processes of the large MWNT producers, but it could and likely eventually will. What this ultimately will result in is the production of MWNTs that is less energy intensive and better for the environment so that MWNTs can enable things like lighter wind turbines and blades and result in a net energy gain rather than loss. If we just walk away from nanotechnology altogether, especially at this early stage, we may never get there.
Dexter Johnson is a contributing editor at IEEE Spectrum, with a focus on nanotechnology.