Chemical companies are eager for new ways to save energy, cut back on hazards, and curtail unwanted byproducts. It’s not just better for the environment. It’s better for the bottom line.
A good target for cleaning up and cutting costs is terephthalic acid—a giant among commodity chemicals. A staggering 100 billion pounds of this white sandy powder are made annually, mostly for use in plastic bottles, easy-care fabrics and food packaging.
“Our novel spray process can make extremely pure terephthalic acid in one step instead of the two required by the existing technology,” said Bala Subramaniam, Director of CEBC.
Fewer process steps often mean less equipment, less cost, less energy, less waste. If CEBC’s process really is cheaper and greener than the current method, companies will take notice.
But the only way to know for sure is to do the math. Former graduate student Meng Li crunched the numbers for every possible expense needed to make terephthalic acid using either the new CEBC process or the conventional one.
As expected, cutting the number of process steps in half is a great way to save money. The new process shrinks operating costs by 16 percent and initial equipment costs by half.
Li also tallied up the potential environmental impacts of the new and old processes. She looked at everything —all the raw materials, products, byproducts, wastes and energy —at every step from pumping crude oil out of the ground to the exit gate of a terephthalic acid factory.
This analysis was tricky. Are greenhouse gases released? Do any materials cause cancer, harm fish or trigger asthma? What about smog? These and many other questions had to be considered.
Fortunately, Li had access to a commercial program’s huge database of air, water and soil toxicity data for all sorts of chemicals and processing techniques. A recent publication in the ACS Sustainable Chemistry and Engineering journal describes her analysis.
“Overall, the new process is better than the old one, but we see a mix of ecological benefits and hotspots,” said Subramaniam. “This often happens when designing green technologies. Fixing one area causes another problem to crop up somewhere else.”
On the bright side, the new process produces fewer air pollutants, such as arsenic, fewer acid rain players like nitrous oxide, and fewer greenhouse gases. This is mostly because the new process takes less electricity than the old one, which cuts back on emissions from coal-fired power plants.
And the downside? The new process uses more acetic acid—the pungent component in vinegar. It can cause a variety of adverse health effects and harm waterways if not treated on-site.
Subramaniam sees this potential ecological risk as an opportunity to improve the process. Finding a way to use less acetic acid is not only better for the environment, but also promises to make a cheaper process even less expensive.
“We now know where to focus our research and development efforts and help our industry partners make business decisions about adopting this new technology,” said Subramaniam.
--Story by Claudia Bode