The manufacture of high-purity salt from brine is a process that requires large amounts of electricity. But at our site in Mariager, Denmark, the exact reverse is also taking place – salty discharge from the manufacturing plant is being used to produce electricity in a pilot project being developed with Danish startup firm SaltPower.

Features - March 2019

It relies on an effect called osmotic power, or “salinity gradient energy” – the energy originating from the difference in salinity between two solutions which is released when they are mixed. The higher the salinity difference, the more energy is available. This effect has also been proposed on a larger scale as a way of generating electricity when rivers flow into the seas and has been dubbed “blue energy.”

“A first mobile demonstration system was completed last year and we are currently undergoing tests of the technology,” said Torben Braendgaard, Manager of the Mariager site. “The test facility uses two discharge streams as input – for the saline solution, it uses brine left over after the evaporation process in our factory. The condensate evaporated from the salt process is used as fresh water.”

"The combined knowledge of Nouryon and SaltPower could lead to the world's first osmotic power plant"

The testing will allow for an accurate determination of the amount of power that can be produced from the streams and at which operational costs the energy can be recovered, Braendgaard explained. “The first results are going into the right direction and the aim is to develop a fully autonomous process. The combined knowledge of Nouryon and SaltPower could lead to the world's first osmotic power plant.”

The project is another example of our search for innovative solutions to improve energy efficiency and sustainable use of energy. We are already using bio-steam at our salt manufacturing plants at Delfzijl and Hengelo, the Netherlands. We also signed a new energy contract that increases renewable energy use in Sweden and initiated a unique green energy purchasing consortium, enabling the construction of two Dutch wind farm projects. Currently, almost half our worldwide energy consumption is from renewable sources.

SaltPower is also working on a related technology to produce electricity using hypersaline water from geothermal wells at Sønderborg, Denmark. “By coupling salinity gradient energy with the heat generation in the geothermal process, we achieve a unique synergy that increases the overall economic viability of geothermal plants,” said SaltPower owner Jørgen Mads Clausen.

“At SaltPower, we have identified the salt industry as a perfect niche for osmotic power, which can bring this clean energy technology to the market. The world needs osmotic power. Looking at the global salt reserves, there is more energy stored away in salt than in oil and it can play an important role in the future energy mix.”

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