Researchers at École polytechnique fédérale de Lausanne (EPFL) have seemingly harnessed the energy used in osmosis to create electricity.
Osmosis is a natural phenomenon in which a two liquids, one with a high salt (or other mineral) concentration and another with a low concentration are seperated by a semipermeable membrane.
The salt molecules will transfer from the highly concentrated liquid to the lower one until a state of equilibrium is reached.
Now that the biology lesson is over, we can explain how these researchers created electricity using this natural system.
The researchers used a membrane made of molybdenum disulfide which had a single nanopore. This membrane separated seawater and fresh water and an electrode was attached to it. As the salt ions pass through the membrane they transfer electrons to the electrode and an electric current.
The membrane only allows positively charged ions to pass through while negative ions are are pushed away. This creates voltage which in turn causes the current to flow.
“We had to first fabricate and then investigate the optimal size of the nanopore. If it’s too big, negative ions can pass through and the resulting voltage would be too low,” lead researcher Jiandong Feng told EurekAlert.
Similarly, Feng says that had the nanopore been too small the current would be too weak.
The trouble with this system is that until now researchers have been using a single nanopore, the challenge is finding a way to make multiple pores uniform.
Should the researchers crack that, this system has the potential to generate 1MW of electricity from 1m² of molybdenum disulfide (which is reportedly found in nature and easy to create).
A number of countries including Norway and Japan have made attempts to harness the osmotic energy but these projects deliver low yields.
Osmotic energy has the potential to play a major role in the push for clean and renewable energy sources. Provided the EPFL researchers can find away to scale up generation.[Source – EurkeAlert] [Image – CC BY 2.0 Daniel Boyd]