Enough electricity for half of Europe.
Have you ever heard of blue energy?
Climate change as well as the Ukraine conflict and the existing dependence on Russia make it necessary to expand renewable energies and to consider innovative ways of generating energy. Water is also considered the elixir of life: why not use water as a source of energy? However, according to the Federal Environment Agency in 2021, electricity generation from hydropower accounted for only 8.2 percent of the renewable energies.
On the one hand, there are ways of using the power of flowing water to generate energy. An example of small and traditional hydroelectric power plants are mills. Energy can also be generated or stored by artificially damming up water. However, research has been going on into another method since the 1950s, as reported by the online portal Research and Knowledge and the SZ: Even when salt water and fresh water mix, energy is produced. This is called osmosis energy. The reason for this is that molecules move to compensate for the salinity.
As a result, up to 2.2 kJ of energy is released for every liter of fresh water that mixes with salt water. So far, the water basins of fresh and salt water were separated from each other by a specific material to generate electricity. When the water passed through this so-called membrane, energy could be gained. A first power plant in Norway was opened in 2009, but proved unprofitable and was closed, according to Statkraft. According to BR, the power plant produced just enough energy to cook food on a stovetop. In order to supply a small town with 30,000 inhabitants with electricity, the power plant would have to be the size of a soccer stadium.
Exactly this could soon change: Using nanotubes to produce a “BNNT membrane” could increase the profitability of “Blue Energy” again. Researchers at Rutgers University in the USA are working on optimizing this membrane. If all the freshwater that flows into the sea was used, the optimized membrane could generate up to 2.6 terawatts of electricity per year. According to research and knowledge, this would be equivalent to the electricity production of 2,000 average nuclear power plants.
Another concept is the use of a specific battery: researchers from Stanford developed a battery in 2019 that is intended to make “Blue Energy” more usable and competitive. They presented the results of their investigations in the specialist magazine ACS Omega. In the new method developed by the researchers from Stanford, a battery based on two electrodes is used instead of a membrane.
The battery is filled alternately with seawater and freshwater. In the process, electrically charged salt particles flow in and out of the electrodes. An external circuit is created from which energy can be obtained. Above all, the material of the electrodes is new and makes the principle more robust. Water from sewage treatment plants that is discharged into the sea is particularly suitable for the battery. According to the researchers, the battery was able to completely cover the electricity requirements of these sewage treatment plants in a model project. In the future, the batteries could generate 625 terawatt hours of electricity annually at river mouths. This covers around three percent of global electricity requirements.
“Blue energy is a huge and untapped source of renewable energy,” said study co-author Kristian Dubrawski, according to a Stanford University press release. “Our battery is a big step towards the practical capture of this energy without membranes, moving parts or energy input.” The advantage of blue energy is also that power plants could be built wherever fresh water flows naturally into the sea and is not dependent on wind and weather is.