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  • Today, 39% of all the fresh water

  • taken from rivers, lakes, and reservoirs in the

  • United States is earmarked for the cooling needs

  • of power plants that use fossil fuels

  • or nuclear power.

  • The problem?

  • A large portion of that water ends up floating away

  • in clouds of vapor.

  • In other words, hundreds of billions of gallons

  • of clean, otherwise usable water are lost each year.

  • But now, a new system devised by a team of MIT engineers

  • could provide an efficient, low-cost way

  • to capture a substantial amount of that lost water,

  • ultimately making power plants less wasteful

  • and more self sustaining.

  • And the water collected could become a source

  • of potable water for parched cities around the world.

  • The motivation to develop this new system

  • stems directly from the inefficiencies

  • of current natural fog harvesting systems.

  • Existing systems, which generally consist of

  • a plastic or wire mesh hung vertically in the path

  • of fog banks, only capture about one to three percent

  • of the water droplets that pass through them.

  • The reason for such a tiny percentage is the result

  • of aerodynamics.

  • As a stream of air passes an obstacle,

  • such as the wires in these mesh fog catching screens,

  • the air flow naturally deviates around the obstacle.

  • Thus, carrying droplets that were heading toward the wire

  • off to the side.

  • The researchers found once they zap the fog

  • with a beam of electrically charged particles

  • known as ions, the opposite effect happens.

  • Not only do all the droplets that are in the path

  • of the wires land on them, but even droplets

  • that were aiming for the holes in the mesh

  • get pulled toward the wires due to the charge.

  • The droplets then collect on that mesh,

  • drain down into a collecting pan,

  • and can be reused in the power plant

  • or sent to a city's water supply system.

  • The team is currently building a full-scale

  • test version of their system,

  • to be placed on the cooling tower of MIT's

  • central utility plant

  • a natural gas co-generation power plant

  • that provides most of the campus's electricity,

  • heating, and cooling.

  • In a series of experiments, the researchers demonstrated

  • the concept by building a small lab version

  • of a stack emitting a plume of water droplets.

  • They then placed their ion beam and mesh screen on it.

  • When the condenser is off, a thick plume of fog droplets

  • rise from the device.

  • Once the condenser is turned on, the plume

  • almost instantly disappears and liquid can be seen

  • condensing on the wire dome.

  • The equipment is simple, and the amount of power

  • required is minimal.

  • And the result is something priceless.

  • Access to free, clean water.

  • The researchers say this could be a great solution

  • to the global water crisis,

  • by offsetting the need for about 70% of new

  • desalination plant installations in the next decade.

  • For example, a typical 600 megawatt power plant

  • could capture 150 million gallons of water a year,

  • representing a value of millions of dollars.

  • The researchers aim to test the system

  • at MIT's central utility plant in the fall.

  • The campus's power plant tests will not only

  • de-risk the technology, but will also help

  • the MIT campus improve its water footprint.

Today, 39% of all the fresh water

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