Introduction
When fresh water and salt water meet, an amazing phenomenon occurs: osmosis. This natural process, already studied in biology, could revolutionize the way we produce energy. Thanks to blue energy, we have a chance to create a renewable, clean and constant source of energy, using the abundant resources of our aquatic ecosystems.
What is blue energy?
Blue energy, or osmotic energy, comes from the difference in salinity between fresh water and salt water. When these two types of water meet, osmotic forces come into play, generating pressure capable of producing electricity. This technology uses semi-permeable membranes to capture the energy released by this natural phenomenon.
An opportunity for renewable and sustainable energy
With an infinite resource provided by rivers and oceans, blue energy has enormous potential. It is estimated that it could cover nearly 40% of the world's energy needs. In addition, it produces electricity without carbon emissions, offering a valuable solution in the fight against global warming.
Limited impact on the environment
Rising ocean temperatures are one of the main causes of stress for corals. When water temperatures get too high, corals expel their zooxanthellae, the microscopic algae that provide them with essential nutrients. This phenomenon is called coral bleaching , because without these algae, corals lose their color and their main source of energy. If the water doesn't cool quickly, corals can't recover and eventually die.
Coral bleaching events are becoming more frequent and severe. For example, Australia’s Great Barrier Reef experienced massive bleaching events in 2016, 2017, and 2020, causing the death of a large portion of this unique ecosystem.
The challenges to be met
Although promising, blue energy is not yet widely exploited. The high cost of membranes and technical constraints are hampering its development. However, researchers are actively working to improve the efficiency of systems and reduce costs. For example, more efficient nanotechnology membranes are being developed.
The Future of Blue Energy
Europe, and countries like Norway in particular, are at the forefront of osmotic energy projects. With growing support from governments and investors, this technology could become a pillar of the global energy transition.
Conclusion
Blue energy offers a fascinating prospect for a sustainable energy future. By harnessing a simple yet powerful natural phenomenon, this technology embodies the potential for large-scale green solutions. As innovations advance, osmotic energy could transform the way we produce and consume energy.
Scientific references
"High-Performance Nanofluidic Osmotic Power Generation Enabled by Exterior Surface Charges under the Natural Salt Gradient" Authors : Long Ma, Zhongwu Li, Zhishan Yuan, Haocheng Wang, Chuanzhen Huang, Yinghua Qiu Abstract : This study explores the use of external surface charges to enhance osmotic energy conversion in nanopores, increasing both ion selectivity and permeability, leading to increased energy production.
"Vertically-Oriented Graphene Oxide Membranes for High-Performance Osmotic Energy Conversion" Authors : Zhenkun Zhang, Wenhao Shen, Lingxin Lin, Mao Wang, Ning Li, Zhifeng Zheng, Feng Liu, Liuxuan Cao Abstract : Vertically oriented graphene oxide membranes exhibit ultrafast ion permeation, enabling an unprecedented power density of 10.6 W/m², surpassing existing materials for osmotic energy conversion.
"Ion Hydration-Controlled Large Osmotic Power with Arrays of Angstrom Scale Capillaries of Vermiculite" Authors : Rathi Aparna, Dhal Biswabhusan, SS Sarath, Kalon Gopinadhan Abstract : Using Angstrom scale vermiculite capillaries, this research demonstrates a high power density of 9.6 W/m² at 296 K, with an exponential increase to 65.1 W/m² at 333 K, highlighting the impact of ionic hydration on osmotic energy production.
"Beyond Power Density: Unexpected Scaling Laws in Scale Up of Characterization of Reverse-Electro-Dialysis Membranes" Authors : Timothee Derkenne, Annie Colin, Corentin Tregouet Abstract : This study reveals that the power density of reverse electrodialysis membranes varies with their size, with smaller membranes exhibiting higher power densities, a crucial observation for the large-scale development of osmotic energy.
"Pressure-Retarded Osmosis" Authors : Fernanda Helfer, Charles Lemckert, Yuri G. Anissimov Abstract : A comprehensive review of the theory, performance and trends of pressure-retarded osmosis, assessing its potential for renewable energy production from salinity gradients. Link to article