LAUSANNE, Switzerland, July 13 (UPI) -- The simple scientific phenomenon known as osmosis has renewable energy researchers quite excited.
A newly devised osmotic power generation system has produced record-setting yields. The system relies on water, salt and an ultra thin membrane -- three atoms thin, to be exact.
More specifically, the system features two liquid-holding compartments separated by a membrane made of molybdenum disulfide. In one container is saltwater and in the other is freshwater.
The membrane allows saltwater ions to pass through its nanopores until the salt concentrations in each container reach equalibrium. Ions are atoms with an electrical charge. As the salt ions pass through nanopores, an electrode captures the electric charge.
The membrane lets only positively charged ions pass through its nanoholes, which slowly turns the device into a dipole, with all the positively charged ions in one container and negatively charged ions in the other. The separation triggers a flow of electricity as the ions pass through the membrane.
"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, a scientist at the EPFL Laboratory of Nanoscale Biology, said in a news release. "If it's too small, not enough ions can pass through and the current would be too weak."
The key to device's never-before-seen electricity yields is its material and thickness. The thinner the membrane, the higher the voltage created by the ion flow and dipole separation.
"This is the first time a two-dimensional material has been used for this type of application," said Aleksandra Radenovic, the laboratory's head scientist.
The next challenge for researchers is to find a way to scale up the osmotic power generation system while maintaining the uniformity of the membrane's nanopores.
EPFL scientists detailed their latest efforts in the journal Nature.