Japan has opened its first osmotic power plant in Fukuoka, making it only the second such facility operational in the world, and kickstarting Japan’s adoption of blue energy as a renewable source of electricity generation.
‘Blue energy’, or ‘salinity gradient’ power plants as they are also known, work by using osmosis to drive a turbine. At present there are two methods at the advanced development stage within the osmotic energy segment, these are Pressure Retarded Osmosis (PRO) and Reverse Electrodialysis (RED)[i].
The new plant in Fukuoka uses PRO. Here concentrated salt water is separated from fresh water by a semi-permeable membrane; this membrane does not allow impurities other than water to pass. As the fresh water moves through and into the salt water it increases pressure, this in turn is used to drive a turbine, generating power. The Fukuoka plant uses concentrated seawater for the saline aspect, and processed water from a sewage treatment facility for the fresh water. The energy generated will be used to power a desalinisation plant which in turn will supply freshwater to Fukuoka city and neighbouring areas.
This plant is only the second such power plant in the world, possessing the capability to generate about 880,000 kilowatt hours of electricity each year, enough to power around 220 Japanese homes. The Fukuoka District Waterworks Agency describes it as "a next-generation renewable energy source that is not affected by weather or time of day and emits no carbon dioxide."[ii]
Osmotic power is not a new concept, with the idea explored in the 1970s. However, in practice its use has seen significant hurdles including cost, efficiency of the membranes in use, and scalability. Further, the energy required to pump the two streams of salt water and fresh water into a power plant can reduce the net gain in energy, making it less desirable than other renewable technologies such as wind or solar.
However, significant advances in the osmotic membrane technology required for effective ion exchange have provided a platform for osmotic power to become a reality rather than a pipe dream. It is now thought that if properly scaled, as much as 15% of the world's electricity, or 13,000 terawatt hours, could be generated by osmotic energy by 2050[iii]
Whilst ‘large-scale’ osmotic plants are limited to a site in Mariager Denmark owned by SaltPower (operational since 2023), and the new plant in Fukuoka, there are several other osmotic projects currently in development. These include Sweetch Energy’s pilot plant, OsmoRhône, which is located at the confluence of the Rhône River and the Mediterranean Sea. Other pilot schemes have taken place previously in Norway and in South Korea.
[ii] Japan's 1st osmotic power plant begins operating in Fukuoka | News | Science Japan
Lauren has extensive experience as an analyst and market researcher in the digital technology and travel sectors. She has a background in researching and forecasting emerging technologies, with a particular passion for the Videogames and eSports industries. She joined the Critical Information Group as Head of Reports and Market Research at GRC World Forums, and leads the content and data research team at the Zero Carbon Academy. “What drew me to the academy is the opportunity to add content and commentary around sustainability across a wealth of industries and sectors.”
