A more affordable, accessible material for seawater desalination

October 5, 2012
Composite pipes for seawater desalination. Credit: Fraunhofer IFAM

There are vast quantities of seawater available; drinking water, on the other hand, is in scarce supply. Desalination plants can convert seawater to drinking water. Yet these plants require pipelines made of a special kind of steel or titanium – expensive material that is growing increasingly difficult to procure. Heat-conducting polymer composites may soon replace titanium altogether.

is a scarce commodity – a fact no longer limited to the desert regions of the world. During the hot summer months, drinking water is rare in Mediterranean countries such as Spain and Portugal, too. As a result, industrial plants that can desalinate and convert it to drinking water are on the rise. Here's how the principle of desalination works: seawater is sprayed on pipes heated by pumping hot gas or hot water through them. Pure water evaporates from the seawater, leaving a salty behind. This process subjects the material and its properties to a diverse array of demands: the material from which the pipes are made must conduct heat and be particularly robust in resisting corrosion and the formation of deposits – and these properties must be durable over a long period of time. And for the water to evaporate properly, the piping must also be easily coated with seawater. This is why manufacturers to date have used only titanium and high-alloy forms of steel. Yet these are very costly. The demand for titanium is also constantly on the rise – as a result of the increase in , the is also competing for this material. The results are delivery delays and further increases in price.

Researchers at the Fraunhofer Institute for and IFAM in Bremen are now developing an alternative to the titanium tubes: pipelines made of polymer composites. The special thing about this method: the are a plastic, and yet they conduct heat. Another benefit: they can be produced in continuous lengths and are correspondingly more economical than their metal counterparts. But what did researchers do to make a polymer heat-conducting? "We introduced metal particles into the material - or more precisely, we add up to 50 percent copper microfibers by volume. This does not change the processing properties of the composite, and it can still be processed as any other polymer would," notes Arne Haberkorn, a scientist at IFAM.

The researchers have already developed the material itself; now they want to optimize its thermal conductivity. To accomplish this, they are installing the piping in a pilot seawater-desalination plant: here, they are testing its thermal conductivity, checking to see how much of a microorganism-based coating forms on the pipes, and how heavily the material corrodes in its salty surroundings. They then optimize the composite properties based on the results. The researchers have set the evaporation process to run at a temperature of 70 degrees Celsius – so there is hot gas heated to 70 degrees pumped through the pipelines. This offers several advantages: fewer deposits congregate on the pipes, the material doesn't corrode as quickly, and the pressure differential between the inside and outside of the piping is not as dramatic.

The usages for the material are not confined to seawater desalination, either. "We developed the pipes for desalination plants because they place the highest demands on the material. Designed with these constraints in mind, it will be no problem using it in the food or pharmaceuticals industries," Haberkorn points out.

Explore further: Nuclear desalination

More information: Researchers will present this heat-conducting plastic at the Composites trade fair, October 9-11, 2012, in Düsseldorf (Hall 8a, Booth A11).

Related Stories

Nuclear desalination

November 20, 2007

New solutions to the ancient problem of maintaining a fresh water supply is discussed in a special issue of the Inderscience publication International Journal of Nuclear Desalination. With predictions that more than 3.5 billion ...

From seawater to freshwater with a nanotechnology filter

June 1, 2011

In this month's Physics World, Jason Reese, Weir Professor of Thermodynamics and Fluid Mechanics at the University of Strathclyde, describes the role that carbon nanotubes (CNTs) could play in the desalination of water, providing ...

Plastic monitors itself

October 18, 2010

A new polymer-metal material that has sensory properties makes it possible to produce plastic component parts that monitor themselves. This material can be combined with various others and used in a variety of different ways. ...

Using the rays of the sun to convert sea- to drinking water

July 1, 2010

Many of the world's remote areas with water shortages also have three things in abundance: Sun, wind and sea. How renewable energies can be harnessed more effectively in the future to transform salty seawater and brackish ...

Wastewater produces electricity and desalinates water

August 6, 2009

A process that cleans wastewater and generates electricity can also remove 90 percent of salt from brackish water or seawater, according to an international team of researchers from China and the U.S.

Recommended for you

Utrecht chemists prove Nobel Prize-winner Olah correct

November 21, 2017

In 1877, Charles Friedel and James Craft discovered a chemical reaction for quickly producing raw materials for plastics, fine chemicals and detergents. More than 100 years later, in 1994, the American George Olah won the ...


Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Oct 05, 2012
So the pipes are 50% plastic and 50% copper. And what is the price of copper?
not rated yet Oct 05, 2012
And what is the price of copper?


Is that too much to ask?
not rated yet Oct 05, 2012
How much better a heat conductor would this material be if silver were used instead of copper? Since it can be extruded, various solar-thermal collectors could take advantage of it. Interesting stuff.
not rated yet Oct 05, 2012
Silver is darn expensive when considering production quantities. Copper will continue to be more expensive also as 3rd world countries become more industrialized.
not rated yet Oct 06, 2012
Yet another reason to mine asteroids. Though manufacturing costs may initially be outrageous!! Gotta do it though, as the Earth only has a certain amount we can dig out of the ground.
not rated yet Oct 06, 2012
Yet another reason to mine asteroids.

What makes you think asteroids are 'solid copper' (or 'solid anything' for that matter) which would be necessary to make mining them more economical than mines on Earth?

I can't really find any source about compositions of asteroids that would indicate that the prevalence/purity of minerals there are worth the (immense) added cost of going there.
not rated yet Oct 06, 2012
Copper is rare element, whereas the titanium is completely abundant and it has ideal properties for most of purposes. The only problem of titanium is, it requires lotta energy for its production. I'm sure, after implementation of cold fusion the role of titanium will become completely reevaluated and it will replace heavy metals from most of their applications.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.