“In an era of major climate change and an increasing need for clean energy, we are proud to be presenting a renewable energy source which has never been harnessed until now. We are also most grateful that the Crown Princess wishes to lend her support to this milestone in our development of osmotic power”, says Statkraft CEO, Bård Mikkelsen.
The energy is based on the natural phenomenon osmosis, defined as being the transport of water through a semi-permeable membrane. This is how plants can absorb moisture through their leaves – and retain it. When fresh water meets salt water, for instance where a river runs into the sea, enormous amounts of energy are released. This energy can be utilized for the generation of power through osmosis.
At the osmotic power plant, fresh water and salt water are guided into separate chambers, divided by an artificial membrane. The salt molecules in the sea water pulls the freshwater through the membrane, increasing the pressure on the sea water side. The pressure equals a 120 metre water column, or a significant waterfall, and be utilized in a power generating turbine.
The following are the overly simplified steps to build a new source of clean, renewable energy for the planet::
1) Take a pressure vessel and divide it into two chambers.
2) Somewhere in the division of the chambers install the same type of semipermeable membrane used in reverse osmosis to make fresh water from sea water.
3) Attach a water pressure-driven turbine generator through piping to the chamber of the vessel that will hold sea water.
4) Fill, but not completely, the turbine-attached chamber with sea water. Fill the other with fresh water to about the same level.
5) Stand back and wait: The salt molecules on the sea water side will pull freshwater through the membrane increasing the pressure on the sea water side as the salinity equalizes (That pressure equals 12 bar or about 175 pounds per square inch (psi), a significant head of water.)
6) Allow the pressurized water to flow through the turbine: let it spin to drive the generator to make electricity.
7) Let the electricity do some work, like light some lights.
8) Give it a name, “Osmotic Power” or its other more scientific name “Pressure Retarded Osmosis (PRO).”
There’s certainly a lot more to Osmotic Power than described above: many vessels and membranes are needed for example. But the technology works. The first prototype osmotic power plant is now operating – in Norway.
Statcraft, Europe’s largest renewable energy company, and global partners have been developing osmotic power for a decade and are now introducing it to the world by opening the prototype at Tofte near Oslo, which took about a year to build.
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