Stenungsund is the backbone of Swedish PVC production. The old mercury-based process is now replaced – a move that will save 20 percent energy, make the product cleaner, and reduce emissions to the sea.

A northbound current ripples the surface of the Askerö Fjord. Salt-white formations pile up against the backdrop: storage vessels and cooling towers, a wickerwork of pipelines that connect them; a dispersed organism.

We are in the petrochemical heartland of Sweden. The organism is INOVYN’s production facility, feeding on salt and natural gas from the North Sea, excreting polyvinyl chloride and sodium hydroxide. Electrolytic cells deep in the core of the structure round up bubbles of gas that rise to the surface, harnessing them in a raw material for industries around the world: versatile and relatively climate-efficient.

”We are putting a lot of effort in reducing our environmental impact and our energy consumption. We have been able to keep up a positive trend, with a steady decline in negative environmental effects from our operations”, says Mikael Rogestedt, CEO of INOVYN Sweden.

A plastic with special properties

Inovyn’s waste water treatment plant. Waste water from the process receives biological treatment. Nitrogen is reduced, and solid particles filtered off. PVC residues are recovered and recycled from the waste stream. Chlorine present in the residual gases is recovered to produce concentrated hydrochloric acid. Photo: INOVYN.

PVC is the third most common plastic material in the world (after polyethylene and polypropylene). Annually in the world, 20 million tonnes are produced. While most other plastics are made from oil only, PVC is made from 40 percent natural gas – and the rest of the raw material is sodium chloride, common salt.

According to statistics from the European plastic industry, PVC is the most energy-efficient plastic, and the one that emits the least carbon dioxide from its production. Its properties are more adjustable than other plastics, too – it can be turned into products as flexible as garden hoses, or stiff as drainpipes – and this versatility allows it to be used in many different applications. Thanks to its durability and longevity, 80 percent is used in the building and construction industry.

Mercury-free chlorine production

PVC differs from other basic plastic materials in that it contains chlorine instead of only carbon and hydrogen. The chlorine is extracted from a salt solution using electrolysis. The by-product is sodium hydroxide, an important input for the pulp industry. In the fall of 2016, the company began to convert the electrolysis process to employ a newer and better technology, replacing old mercury cells with modern membrane cells.

”By the end of the decade, INOVYN will have invested in the region of €1 billion across its European assets through a range of safety, sustainability and innovation-led projects including its complete transition from mercury to membrane cellroom production”, says Chris Tane, CEO of the INOVYN group.

While the Stenungsund facility has recorded the lowest mercury emissions among all chlorine factories in Europe with mercury cellrooms, the cleaner membrane method is always preferrable. In 2001, the chlor-alkali industry in Europe made a voluntary commitment to make the large investments necessary to phase out mercury cells by 2020. Two thirds of the facilities switched to membranes between 2001 and 2015. In 2017, only a sixth of the volume of chlorine produced in Europe came from a mercury process. When membranes where so well established, the mercury process was no longer considered best available technology by EU standards. It was prohibited as of December 2017, and in May 2018, as covered by an exemption granted by the Swedish Chemical Agency, INOVYN Stenungsund’s old facility was shut down.

Several environmental benefits

”Many colleagues and a great number of entrepreneurs are involved in building the new chlorine membrane cellroom. The project leads to a number of substantial advantages for the environment; mercury will not be used, and the new membrane technology will reduce energy consumption significantly”, Mikael Rogestedt explains. He adds that the new chlorine production marks the beginning of a major investment in the Stenungsund facility.

The energy-intensive electrolysis process is responsible for 70 percent of the company’s energy consumption. With membrane cells, 20 percent less energy will be required – saving the equivalent of heating for 4000 homes every year.

”We continually strive to improve our performance in all key areas of our operations to make INOVYN fully sustainable. This investment will deliver long term, competitive and sustainable supplies of chlorine and caustic soda to key industry sectors across Sweden and the wider Northern European markets”, says Filipe Constant, Business Director at INOVYN.

VinylPlus: an industry commitment

”Sustainable development and circular economy is assuming more and more significance in our internal strategies and our internal company development, but we are also working side-by-side with others”, Mikael Rogestedt says.

PVC is a versatile material, and the most used plastic in the construction industry, for instance in pipes and cables. It is also frequently used elsewhere, such as in vehicles, electronic appliances and medical products.

In a collaboration with other companies in the Stenungsund petrochemical cluster, INOVYN has begun to examine ways to recycle plastics chemically, by gasifying them to create new raw materials. At the European level, INOVYN also participates in the voluntary commitment VinylPlus. It was initiated by the European PVC industry in 2000 to lead the way towards sustainable development throughout the material’s value chain.

VinylPlus phased out lead as a stabilizer in 2015, and a sustainability label for PVC products is under development. Recycling is one of the focus areas; since the commitment’s inception, 4.2 million tonnes of PVC has been recycled by way of VinylPlus.

”For nearly 20 years, VinylPlus has led the way to a circular economy by improving the sustainability performance of PVC. Our programme brings together the entire value chain – PVC manufacturers, additives producers, converters and recyclers”, says Brigitte Dero, VinylPlus’ General Manager

“We are confident that we will achieve our goal of recycling 800 000 tonnes of PVC annually in Europe by 2020”, Mikael Rogestedt concludes.

The article was published in October 2018.