Subsea desalination moves forward following Waterise partnership

The first major subsea desalination plant is moving ahead following collaboration between Norwegian company Waterise and Rosenberg Worley.

Positive news from Stavanger

Back in the summer, Aquatech Online investigated Norwegian start-up Waterise and its novel approach to operate a modular desalination system 400m underwater on the seabed.

Since then, positive news has emerged from Stavanger, Norway, with the first major subsea desalination plant now moving ahead.

Engineering and fabrication company Rosenberg Worley has been awarded the contract to develop a cost-efficient solution for the plant's modularisation, installation and operation.

Each subsea plant module is expected to produce 13 million gallons of freshwater per day (59,000 m3/day) – said to be enough to support a mid-to-large-city.

Borja Blanco, CEO of consultancy Aqua Advise and chief commercial officer at Waterise, told Aquatech Online that the organisation is "getting pretty close to a real project opportunity" but did not elaborate further.

How sub-sea desalination works

By submerging containerised desalination systems below sea level, the Norwegian company believes it leverages natural hydrostatic “pre-membrane pressure”.

A pilot project in Boknafjorden, Norway, has so far demonstrated a 40 per cent reduction in energy compared to conventional reverse osmosis (RO) technologies.

“An umbilical connection provides electricity and communication, as well as a pipeline that brings water back to the shore.”

The desalination system combines existing RO membrane technology from DuPont Water Solutions with existing Norwegian subsea technology used in oil and gas applications over the last two decades.

At a depth of 400m, the plant is connected via an “umbilical connection”, a cable that provides electricity and communication, as well as a pipeline that brings water back to the shore.

The distance to the shore will depend on the location to reach the 400m depth, but on average, the company said this would be between 5-7km from the shore.

Trial results and Worley partnership

Results from the Boknafjorden trial have shown an energy consumption of 1.8-2 kWh/m3 compared to 3.3 to 3.6 kWh/m3 for land-based, terrestrial desalination.

“We’re now taking our technology into the first full-scale plant.”

Rosenberg Worley will become a strategic partner “based on its competence and capacity in both subsea operation systems as well as desalination,” said Niels Petter Wright, CEO of Waterise AS.

He added: “We’re now taking our technology into the first full-scale plant.”

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