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.