Energy-saving chlorine manufacture

That vital volt less

Chlorine is needed for some two-thirds of all chemical products, including plastics. And that comes at a cost. The production of this important basic chemical is one of the most energy-intensive processes in the chemical industry. Covestro has co-developed a process that reduces the amount of electricity required by up to 30 percent.
Covestro co-developed a technology for chlorine production which uses up to 30 percent less electricity than the conventional process.
Chlorine is highly reactive and forms compounds with virtually all other elements. It does not occur naturally in its pure form, however, and is only found in combination – as in the case of table salt, from which chlorine can be obtained using electrolysis.

This uses a great deal of energy, though. As a result, Covestro co-developed oxygen depolarized cathode (ODC) technology, which uses up to 30 percent less electricity than the conventional process. Researchers across the globe had been trying to find a solution of this kind for decades.

Just two volts instead of three

The new technology is based on the membrane process in chlor-alkali electrolysis, which has become the standard for chlorine production. In this process, chlorine, caustic soda and hydrogen are usually produced from table salt and water.

In ODC technology, the hydrogen-generating electrode normally used in the membrane process is replaced by an oxygen-depolarized cathode. Supplying the cathode – the negative pole – with oxygen suppresses the formation of hydrogen. Only chlorine and caustic soda are produced. As a result, a voltage of just two rather than three volts is required – around one-third less.

If for example all chlorine producers in Germany were to introduce the process, which is market-ready, the country’s total electricity consumption could be cut by one percent. That is roughly equivalent to the electricity consumed annually by the large city of Cologne. ODC technology could thus play a key role in Germany’s energy revolution, which focuses in particular on improving energy efficiency. The process can also help protect the climate, because the electricity savings go hand in hand with up to 30 percent lower CO2 emissions.

Huge sales potential

This innovation delivers outstanding economic benefits, too, and can help German technology succeed on the global market. Development partners Covestro and ThyssenKrupp Uhde Chlorine Engineers believe that ODC technology has a huge sales potential over the coming years.

The process has been operating successfully on an industrial scale at Covestro’s plant in Krefeld-Uerdingen in Germany since 2011 and has been commercialized worldwide since 2013.