Traditional hydropower relies on flowing water to generate electricity. However, it is possible to use standing water as a power source. Currently, all methods that use stagnant water to generate energy must manually move the water in some form, typically with a pump. Here are three of the most promising ways to take advantage of standing water.
While this technique is still under development, it shows great promise for using stagnant water as an energy source. In 2020, scientists from the Indian Institute of Technology published a paper outlining their method for using a graphene-based generator to create electricity.
The researchers collected water from rivers, lakes and seas. They then dipped the generator — created with modified graphene flakes coated on filter papers — in the stagnant water samples. The device produced a voltage of up to 570 millivolts and retained its efficiency for several days.
The scientists also invented a generator using silica spheres and small channels to generate energy from flowing water. By changing the number and diameter of the spheres, they were able to make the device even more efficient at generating electricity.
Currently, neither device creates enough electricity for commercial purposes, but they show promise as a new form of energy generation. The method does not release any greenhouse gases, making it an environmentally friendly way to utilize stagnant or running water.
Another way to use stagnant water as an energy source is via pumped-storage hydroelectricity. This widely used energy storage method also works with flowing water. During periods of low energy demand, a pump moves water to a higher elevation to raise its gravitational potential. The higher the water is, the more potential energy it holds.
During periods of peak energy demand, the water flows through turbines back down to a lower elevation, producing electricity. Pumped-storage hydroelectricity does not actually generate energy — it merely stores it and converts it from one form to another. That is because pumping it upward uses energy in the first place. However, this technology is very useful for taking advantage of stagnant water sources to generate electricity during periods of high demand.
Stagnant water can contain environmental toxins and serve as a breeding ground for mosquitos, making it a less-often-considered choice for energy generation. However, as the world population grows, droughts intensify and the demand for energy increases, underutilized resources take on a new value — even those previously thought of as mere hazards.
Around 97% of the world’s water is in the ocean. Much of the remaining 3% is untreated wastewater and sewage that currently has no use. However, scientists at Myongji University in Seoul and the Korea Institute of Science and Technology have pioneered a material that purifies wastewater and generates electricity.
The device consists of a conductive polymer and porous membrane to accomplish two tasks at once, turning sewage into a valuable resource. It relies on pumps to make stagnant water flow across it. As it captures ions, the membrane generates power continuously. The material is also easy to print.
Following the success of their preliminary design, the researchers are now working on creating a drinking-safe version for real factories. They hope the material will help generate energy while removing harmful microplastics, heavy metals and other contaminants from drinking water.
The world is more reliant on electricity than ever. While pumped-storage hydroelectricity is commonly used to store and convert energy from standing water sources, scientists are always looking for new solutions to the energy problem. Stagnant water may represent an untapped resource, especially in underdeveloped nations or areas with less wind and solar potential.