My Wacker Chemie sustainability stories are still in the line-up but with this news from Bayer MaterialScience last week about their eco-friendly electrochemical chlorine production, I might as well include some tidbits from Wacker's chlorine production as well.
Bayer said it is building a new chlorine plant that uses common salt with annual capacity of 20,000 metric tons/year at its Chempark Krefeld-Uerdingen in Germany. The new facility will use a oxygen depolarized cathode technology, which the company said, will reduce electricity consumption by up to 30% lower than in standard membrane technology, resulting in an indirect reduction of up to 10,000 metric tons of CO2 emissions each year.
Like what Wacker mentioned during my press field trip to their Burghausen, Germany, site, chlorine production is currently one of the most energy-intensive processes in the chemical industry. Currently, chlorine is mainly produced using the membrane process.
Bayer said their new technology enables electrolysis to be performed at a lower voltage. The company has been using its oxygen depolarized cathode technology based on hydrochloric acid electrolysis on a large industrial scale at the Bayer Integrated Site Shanghai (BISS) in China and in Brunsbuettel, Germany. The Chempark chlorine facility is scheduled to start operating in the first half of 2011.
Now for Wacker's chlorine production in Burghausen, Germany, (if I understand my scribbled notes correctly), is that they also use common rock salt that came from their own salt mine in Stetten as raw material.
The salt goes to a an ion-exchange membrane electrolysis process that consumes about 2,200 KWh/ton of NaOH. This process, according to Wacker, is 25% more energy efficient compared with mercury and asbestos processes. The facility produces 155 tons/day of chlorine and 170 tons/day of caustic soda
Now, based on these information, it seems the Bayer processing is greener but there are other factors to be considered such as sustainability of energy source perhaps? or how does a facility uses their chlorine, the waste streams if they can be recycled, logistics and sustainable sourcing of raw materials, and so on and so forth...I'm not an expert in chemical processing so I leave it to the readers to decide.
The good news is that major chemical companies are always trying to improve their processing especially if they can save money (by reducing energy use) and lower their GHG emissions at the same time.