How wave energy is making seawater drinkable

12th April 2013 By: Karel Smrcka

Aconcept for producing drinking water from seawater using wave energy has been developed at Aalto University, in Finland.

This appears to be ground-breaking technology, as similar plants currently in operation use either electricity or thermal energy.

The new technology is expected to alle- viate the global chronic lack of potable water. According to an estimate by the United Nations, by 2025, up to 1.8-billion people will live in areas that experience drinking water scarcity.

The AaltoRO Concept
The AaltoRO concept was developed by Finland’s Department of Energy Technology. It is based on a panel that is 25 m to 30 m wide and 20 m tall and moves under the surface of the sea using wave power to pressurise seawater. The pressurised water is piped to a land-based device that uses reverse osmosis to remove salt from the seawater. Further treatment of the water ensures it is fit for drinking.

Depending on the location, the price of the system is estimated to be between €2.3-million and €4.7-million, and the maximum production capacity of a single AaltoRO device is 3 700 ℓ of drinking water a day.

According to the calculations, the AaltoRO system is most suitable for use in Australia, the Canary Islands, Chile, Hawaii, Southern Africa and the western seaboard of the US.

The feasibility of the concept for freshwater production was studied in a thesis by Markus Ylänen as part of a larger project run by the Finnish Funding Agency for Technology and Innovation. The companies involved in the project are AW-Energy, Nurmi Hydraulics, Watman Ab Vedenkäsittely and Waterpumps WP.

Tidal Power’s Huge Potential
Many countries have underestimated the amount of electricity and other benefits that could be generated from tidal sources and there are analyses available that, for instance, estuary barrages and tidal streams could provide more than 20% of countries’ demand for electricity.

According to the International Desali- nation Agency (IDA), 632 freshwater production plants were built between July 2011 and August 2012. The IDA says the production capacity of existing plants is 74.8-million cubic metres of water a day. The world’s largest plant producing freshwater from seawater is in Hadera, Israel. The plant’s production capacity is 350 000 m3 of freshwater a day.

Wave and Tidal Energy Around the World
Despite high costs, many experts insist that tidal power is more reliable than wind. The predictable nature of tides makes them an ideal renewable source of energy.

At present, engineers try to tap tides in two ways. One involves building barrages across tidal estuaries that use the ebb and flow of the waters to turn turbines, and a major project of this type has been proposed for the Tiver Sdevern. The other method involves placing turbines underwater in fast-flowing tidal streams in areas such as in coastal waters, for instance, around Cornwall and Scotland.

The SeaGen project, in Northern Ireland, is at this moment the largest grid-connected tidal turbine in the world. In Perth, Australia, Carnegie Wave Energy has secured environmental and maritime safety approvals for the Perth Wave Energy Project. The commercial-scale project, which uses Carnegie’s CETO wave system, will power Australia’s largest naval base, HMAS Stitring, on Garden Island, in Western Australia.
Cherbourg, in France, is to receive a £60-million makeover for tidal energy. Facilities at the French ports of Cherbourg and Caen Ouisterham are to undergo a multimillion-euro expansion to pave the way for the development of tidal energy projects in the area.