Today, Norway's Aftenposten News announced that the government energy provider, Statkraft, has made the decision to build the world's first pressure retarded osmosis (PRO) power plant prototype in Hurum, Norway. In the process, two solutions with different salt-concentrations are used (often freshwater and salt-water). A semipermeable osmotic membrane separates the solutions and only lets small molecules like water-molecules pass through. The water attempts to decrease the salt-concentration on the side of the membrane that contains the most salt. The water therefore streams through the membrane and creates a pressure on the other side. This pressure can be utilised in order to gain energy, for example by using a turbine and a generator.

Here is a simple schematic of such a system to be used in a 100 kW plant :

This new development marks the first step in a technology that may one day provide a significant portion of the world's energy. Statkraft is the first company to venture into this technology because it is far more costly than fossil fuel. (However, if the total cost to the environment of fossil fuels were to be calculated, these differences may disappear.) Norway is seriously committed to reducing global warming and this new technology is in keeping with that commitment.

While freshwater/seawater gradients are rather costly, there is a much greater short term economic potential for freshwater/brine and seawater/brine gradients . As a result, utilizing brine from inland salt lakes, solution mines and solar salt operations may be a more economically feasible approach than the Statkraft operation. Whatever the case, through this new development, we can look forward to a green future with the incredible Saline Turbine!