Last month, Japan opened its first osmotic power plant in the city of Fukuoka, and only the second of its kind in the world. The plant is expected to generate 880,000 kilowatt hours of electricity per year, which would help power a local desalination plant that provides fresh water to, and in areas near, the city.
Developing power from osmotic energy is an emerging technology that is still far from being able to fill a larger chunk of the power grid. However, this renewable energy holds great potential since it is available regardless of weather or other conditions — a common problem with solar and wind energy.
What is osmotic energy, and how does it work?
Osmotic energy is generated through the phenomenon of osmosis and is being tested in areas where freshwater enters saltwater. In such a case, the water moves from an area of lower solute concentration, the freshwater, into an area of higher solute concentration, the saltwater. This movement causes a difference in pressure between both sides that can be harnessed to produce electricity.
The main component of this technology is a semipermeable membrane that sits at the point between the two different concentrations of water. This membrane blocks salt from moving across, and as a result, freshwater pushes into the saltwater to dilute it. Eventually, as this side increases in pressure and decreases in salinity, water is channeled through a turbine to produce power.
The amount of electricity that can be generated from this method, consequently, depends greatly on the efficiency of the membrane. The concept of osmotic power has been around since the 1970s, but its practical implementation has consistently faced the challenge of developing membranes that are efficient enough to generate a meaningful amount of electricity.
Before Japan’s Fukukoka plant, the company SaltPower built an osmotic power plant in Mariager, Denmark, in 2023. Furthermore, there have been demonstration installations in Norway and France.
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The road to renewable energy and lower carbon emissions
Osmotic energy is a clean energy source, unlike hydroelectric or fossil fuel-based energy sources, as it does not generate carbon dioxide emissions. It is also a renewable energy source, unlike nuclear, as it relies on the natural and continuous mixing of freshwater and seawater — a process that will persist as long as rivers flow into the ocean.
More research is still required to gain deeper insight into long-term effects on the environment, but at the moment, the ecological impact is minimal as water returns to its original environment.
The scalability and lower raw material cost of osmotic energy could make it a very good avenue to power isolated subjects such as a desalination plant or a small town. French company Sweetch Energy even estimates that their osmotic plant in the Rhone River will have a production capacity of 500 megawatts, enough to power 1.5 million households, far bigger than just an isolated subject.
Osmotic energy is estimated to have the capability to meet up to 20% of global electricity demand. For comparison, nuclear energy currently provides around 10% of the world’s electricity, while solar and wind together account for roughly 12–15% and are rapidly expanding.
None of these sources is expected to meet global needs on its own; however, if osmotic power can scale successfully, it could become a vital addition to the world’s renewable energy portfolio.
Editor’s Note: The opinions expressed here by the authors are their own, not those of Impakter.com — Cover Photo Credit: NASA.
