MIT steam collector captures pure water for reuse in power plants
Nuclear and fossil fuel power plants consume huge amounts of water for cooling, which then goes to waste as water vapor. MIT engineers have now developed a system that can capture and recycle that lost water.
Big plumes of white steam are a common sight around power plants, but while it’s somewhat a relief to know it’s not carbon dioxide or, worse, greenhouse gases, they do represent how much water is being consumed.
In recent years, MIT engineers have developed a system that can harvest that water vapor and collect it as very pure water. That can then be cycled back into the plant’s other systems that require water, such as cooling or boiling.
Previous technologies designed to wring water out of fog or vapor usually rely on materials with high surface areas that water droplets can cling to. The MIT tech does this too, but takes a more active role. First the droplets are zapped with an ion beam to give them an electrical charge, then they pass through wire meshes that have the opposite charge. That means the droplets are strongly attracted to the mesh, where they gather and fall into a tray below for collection.
After a series of lab tests showed that the concept worked, the team tested the system in two of MIT’s research power plant facilities, one powered by natural gas and the other nuclear power. In both cases, the plumes all but disappeared and the captured water was extremely pure – 60 times more pure than what normally goes into a power plant cooling system, and around 10 times more pure than regular drinking water.
In larger plants where this captured water is fed back in, the team says that the system should be able to reduce water consumption by as much as 20 percent. The purity means that it could also be piped back into a general water supply.
The team says that two large-scale tests are due to begin this year in commercial plants – one a 900-MW power plant and the other a chemical manufacturing plant.
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The major issue with this system involves the heat gain of the steam - where is it going when electrochemically attracted to the charged mesh. I am aware the reduction in water loss is a massive environmental improvement, but with the tremendous thermal gain water molecules require to change phase - is there no way to capture that heat and use it for energy production or to improve efficiency somewhere in the original power plant configuration?
Unlike other commentors - this is a pure theoretical exercise - I am a physician, not a power engineer so if this conjecture is pure fantasy - enjoy it! But it seems like condensing H2O from vapor to liquid should impart heat to the grid or the passing air flow. The BTUs have to go somewhere! Are they just lost?
You are partly right, Malatrope, as the water vapor will eventually condense back down into liquid water again, that is what we call the water cycle. The capture of ultra pure water for specific uses MIGHT be cheaper that having a dedicated process for that alone, but I'd need to see some hard data to prove it.
And Johannes, reducing the water usage by only 20% doesn't make it look like a very economical endeavor, why not reduce it by 80%? I like to think that those boys and girls over at MIT are probably smart enough to take ALL of the various factors into consideration in something like this, and come up with a good answer. At least I hope that they can!