More than two years after the first osmotic power prototype was opened at Tofte, is a new project on the way! Another Norwegian location seems to have been identified as the most suitable for the new facility: Sunndalsøra.

In the autumn of 2009 the world’s first osmotic power generator was launched in the village of Tofte in Norway.

Statkraft, a state owned electricity company known for being the leader in the development of osmotic power, has long investigated a viable solution to generate electricity through the osmotic process. At the time the first prototype was opened in 2009 efforts were focused on testing components, processes and membranes. The main aim of the company was to make the whole process much more efficient and less expensive in order to apply this technology for renewable energy production.

Since now one of the most difficult hurdle to get over has been to create more efficient membranes. However, according to a recent declaration released by Stein Erik Skilhagen, head of osmotic power at Statkraft, the company has managed to increase membranes efficiency and now they are testing components that are ten times more efficient than those first used in 2009.

This represents an important step forward in the development of osmotic power generation even if better results are expected in order to make the new technology competitive with conventional and non-conventional sources of energy.

Water shortages and the increased demand for energy are probably two of the main issues at the centre of the international agenda. And very often some of the most striking events on the news headlines are driven by one of the above-mentioned issue. This is the reason why it is important to understand what is happening in these fields all around the world. And how is the research evolving.

Is any proposal presented as a viable one a real opportunity to be developed? What are the pros and cons?

If we consider the new technology briefly introduced in this article, it is first important to understand its meaning.

Osmotic power or salinity gradient is the energy obtained from the difference in salt content of fresh and salt water. In fact, having two communicating tanks, respectively containing fresh and salt water, and having a semi-permeable membrane in-between the two. And assuming that our membrane is permeable to smaller solvent molecule (i.e. water), but not to larger solute molecules (i.e. salt). We define the osmosis process as the natural flux of water molecules from the tank containing fresh water to the one containing salt water in order to equalize the solute concentration on each side.

In an osmotic power plant, fresh water flows from its tank to the one aside containing salt water. The level in the brackish tank increases until it flows out of the tank and run a turbine that activates a generator to produce electricity.

One of the strongest arguments in favour of the osmotic power production lies in its environmental friendliness. In fact, the required mix of fresh and salt water is something that already exists in nature every time a river flows into the sea or into a salt water lake. It means that, having assessed the right location for the new plant, this technology simply takes advantage of a natural process.

Furthermore, experts say that, contrary to the other renewable energy sources, this one is not dependent on weather conditions - as it’s the case for solar panels or wind turbines - making this technology much more efficient.

In reality, it’s a simplistic generalization to say that renewable energy sources are dependent to weather conditions. Some important steps forward have been taken to break it. I remember having written an article a few months ago about solar panels being able to produce energy 24 hours a day, 7 days a week through the supply of a storage tank.

Generally speaking, we could say that the world of renewable sources has been developing new viable solutions in all fields and that we hope this trend will increase even more in the years to come.

It could seem that no obstacles exist to limit the push towards a more conscious management of our planet. Of course this is not the case and besides the strong arguments in favour of the osmotic power, we can’t underestimate some contre-arguments. The first one has to do with semi-permeable membranes production. As already mentioned, it is important to cut costs while increasing efficiency otherwise this technology won’t be competitive enough. Secondly, the electricity generation process requires another important factor: an efficient use of water resources. The latter is particularly important because it reminds to the issue of water shortage. In fact, we are now pumping water from rivers faster than nature can regenerate making our main basic need – water – not renewable anymore. As a consequence, reducing waste is paramount, and therefore it is important to assess realistic locations for osmotic power plants where water won’t be applied to different uses as to irrigate croplands. It’s is difficult though important to prioritise our needs through a careful and respectful analysis of all the aspects involved.