It is widely known that the sea and the rivers are a source of green energy such as hydro and tidal power. But it has been recently discovered that they are also the source of osmotic power, popularly known as blue energy.
Shortly, when fresh water comes into contact with seawater, it releases large amounts of energy that we can use to generate electricity.
How is blue energy produced?
This type of green energy is produced mainly at the mouths of the rivers, where fresh water flows into the sea or the ocean. This is where takes place a physical-chemical process named osmosis in which a semipermeable membrane allows only certain substances to pass into the cells of living beings. And we certainly still don’t lack living beings in waters – we have it all from fish, bacteria, corals, sea plants etcetera. (Hopefully this type of “fuel” never disappears).
An osmotic power plant aims to copy nature using an artificial membrane separating two chambers: one with freshwater and one with sea water. Fresh water is able to pass through the membrane increasing the volume in the salt water reservoir. This produces a significant increase in pressure, equivalent to a 120 meters waterfall! With this power you can easily move a turbine and generate electricity.
Blue energy has two main advantages: it does not imply any gas emissions or contamination (unlike the fossil fuels) and it can produce electricity continuously as it does not depend on weather conditions (unlike solar and wind energy).
Blue energy today
People have started being interested in this type of green energy: especially the Norwegians and the Dutch are very aware of its great potential (Of course they are!). But aside from being aware of it they started working on power plants.
The Norwegian company called Statkraft launched in 2009 the first prototype of blue energy plant. It was placed in an industrial area, south of Oslo and had the objective to generate 10 kW of electricity. The two tanks were filled with 10 liters of fresh water and 20 liters of sea water per second, while several pipes filtered the fluids to prevent the clogging of the membrane.
On the other hand, the Dutch idea is to create a power plant at the mouth of Rhine and channel the water from the river and from the sea to harness their potential. They estimate that the estuary could generate 1 GW of power – enough to supply clean electricity to 650,000 homes (which is small city, a new eco city in that matter).
Obstacles in using blue energy
The main drawback of the osmotic energy is the cost. Compared to a conventional power plant (using fossil fuels) a blue energy power plant is 36 times more expensive, due to the fact that the artificial membrane is very hard to produce with the current technology.
Also, we have to take into consideration engineering problems: building a large power plant and lower it deep in the sea or in the ground (which is what the Dutch plan to do) it is extremely difficult. We also need to protect the marine organisms from the turbines and the salinity fluctuations.
Blue energy used worldwide
Are we ever going to use blue energy at a large scale? That is the main question. While the Norwegian and the Dutch go ahead with their prototypes, the rest of us are waiting for a new cheaper artificial membrane to appear before we install a blue power plant in our countries. Hopefully this doesn’t take too long, as the need of green, effective energy solutions is constantly increasing.