There are few efficient ways of producing energy and sometimes these ways have their limitations. What could be a better alternative to solar power and wind power? Solar power is becoming more expensive than usual, apart from that what if the sun doesn’t shine on some days? the same goes to wind power, what if the wind doesn’t blow? looking at these natural limitations you would agree there’s a little problem somewhere, if not huge.
A group of researchers at the Ecole Polytechnique Fédérale de Lausanne (EPFL) seem to have found a simple way to produce a lot of energy through osmosis. Osmosis is the movement of water molecules from the region of the higher concentration, to that of the lower concentration via a permeable membrane, in essence when salty water hits fresh water across a permeable membrane osmosis occurs. Atom with an electrical charge (salt ions) passes through the membrane until the amount of salt is equal on both sides.
Since there is production of electrical charge, researchers simply captured the charges as it moved across the membrane separating the fresh and salty water. They achieved this by creating two tiny membranes, which is three atoms thick, made of molybdenum disulfide and then they made a tiny hole in the membranes, after this osmosis pushed the electrically charged salt ions through this nanopore. According to Jiandong Feng, lead author of the research;
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. If it’s too small, not enough ions can pass through and the current would be too weak
This technique is unique thanks to the fact that nanopore allows positively charged ions through, and keeps out most of the negatively charged ions. A generator attached to the membrane collects this energy.
According to the researchers, a one meter square membrane with nanopores across about 30 percent of its space could produce one megawatt of energy, this is enough to light 50,000 standard energy efficient light bulbs, cool right?
Although a nice idea, but will require lots of work “We can control with sub-nanometer precision pore size when we work with the single nanopore. To scale the process and have millions or trillions of pores, that would require a different nanopore fabrication process.” Radenovic says that’s exactly what they’re working on now. If all goes as planned, huge amounts of energy will be created through this method.
Osmotic power, salinity gradient power or blue energy is the energy available from the difference in the salt concentration between seawater and river water. Two practical methods for this are reverse electrodialysis (RED) and pressure retarded osmosis(PRO). Both processes rely on osmosis with ion specific membranes. The key waste product is brackish water. This byproduct is the result of natural forces that are being harnessed: the flow of fresh water into seas that are made up of salt water.
The method of generating power by pressure retarded osmosis was invented by Prof. Sidney Loeb in 1973 at the Ben-Gurion University of the Negev, Beersheba, Israel. The idea came to Prof. Loeb, in part, as he observed the Jordan River flowing into the Dead Sea. He wanted to harvest the energy of mixing of the two aqueous solutions (the Jordan River being one and the Dead Sea being the other) that was going to waste in this natural mixing process. In 1977 Prof. Loeb invented a method of producing power by a reverse electrodialysis heat engine.