The first world-scale chlorine plant based on oxygen depolarized cathode electrolysis technology has been successfully started up in Tarragona, Spain. Covestro and thyssenkrupp nucera worked closely together to develop the innovative and energy-efficient electrolysis technology. The oxygen depolarized cathode electrolysis technology is based on thyssenkrupp nucera’s proven electrolysis technology. The supplier of world-leading technologies for high-efficiency electrolysis plants is also responsible for the engineering, procurement and construction management of the new production plant.The process for producing chlorine and caustic, which was jointly developed by thyssenkrupp nucera and Covestro, requires a lower voltage compared with the prevailing conventional chlor-alkali electrolysis. Therefore, the energy consumption of the plant can be reduced by up to 25 percent and up to 22,000 metric tons of CO2 emissions per year can be avoided (based on the energy mix at the start of construction planning in 2018). The new plant thus makes an important contribution to Covestro’s goal of being operationally climate-neutral by 2035.Covestro is one of the world’s leading manufacturers of high-quality plastics and their components. With the world’s first large-scale chlorine production plant, the company is securing an efficient, permanent and independent supply of chlorine and caustic soda for MDI production in Tarragona, thus strengthening the European production network for MDI. Methylene diphenylene diisocyanate is a precursor for the production of rigid polyurethane foam, which is used to insulate refrigeration appliances and buildings.