Engineers of the Massachusetts Institute of Technology have invented cost-effective way to produce clean drinking water from the water vapors of power plants.
About 39 % of all fresh water pumped from rivers, lakes and reservoirs in the United States is allocated for cooling towers of nuclear and thermal power plants. Most of the wastewater then evaporates into the atmosphere. MIT scientists offer an innovative solution that will not only avoid water losses, but also allows to obtain an additional source of clean drinking water for nearby cities.
The principle behind the new technology is simple: the air saturated with water fog is zapped with a stream of electrically charged particles – or an ion beam. Water droplets, having an electric charge, rush to a huge screen of wire mesh, which is placed in the path of foggy masses. Water is collected on this grid and flows into the collector. The resulting H2O can be reused at a power plant or fed into a water supply system. The quality of such water is absolutely safe.
At the beginning of their way to the invention of water vapor capture technology, Maher Damak Ph.D and associate professor of mechanical engineering Kripa Varanasi experimented on natural fog. The team then focused on the possibility of disposing of the steam plume coming out of the power plant cooling tower. This stream of water vapor is much more concentrated than any natural fog, and therefore the whole system can function even more efficiently.
Even if the water circulating in the cooling tower is salty or contaminated, the capturing of evaporated water is a distillation process, i.e. the water vapor of the power plant is condensed on the grid after being zapped with the ion beam and converted into high-quality distilled water.
A typical 600-megawatt power plant can provide up to 150 million gallons (567 million liters) of water per year, saving millions of dollars, explains Varanasi.
According to him, as the system will be further improved, its productivity will grow.
Scientists also propose to use their scheme in power plants located on the coastal area. Their cooling towers work, as a rule, on seawater. Thus, there is no need for the construction of desalination plants. It is enough only to install conversion wire mesh screens on cooling towers, especially since it will cost three times cheaper than building standalone desalination unit.
Currently, scientists are engaged in the construction of a full-scale version of their system, which will be placed on the cooling tower of the Central Utility Plant, a natural-gas cogeneration plant on the territory of the MIT campus. It is expected to be installed it by the end of summer and run in test mode in autumn. As noted, the successful testing will open the doors for the industrial development of new technology.