Pentagon weapons-maker finds method for cheap, clean water

[frigidmagi]

reuters

A defense contractor better known for building jet fighters and lethal missiles says it has found a way to slash the amount of energy needed to remove salt from seawater, potentially making it vastly cheaper to produce clean water at a time when scarcity has become a global security issue.

The process, officials and engineers at Lockheed Martin Corp say, would enable filter manufacturers to produce thin carbon membranes with regular holes about a nanometer in size that are large enough to allow water to pass through but small enough to block the molecules of salt in seawater. A nanometer is a billionth of a meter.

Because the sheets of pure carbon known as graphene are so thin - just one atom in thickness - it takes much less energy to push the seawater through the filter with the force required to separate the salt from the water, they said.

The development could spare underdeveloped countries from having to build exotic, expensive pumping stations needed in plants that use a desalination process called reverse osmosis.

"It's 500 times thinner than the best filter on the market today and a thousand times stronger," said John Stetson, the engineer who has been working on the idea. "The energy that's required and the pressure that's required to filter salt is approximately 100 times less."

Access to clean drinking water is increasingly seen as a major global security issue. Competition for water is likely to lead to instability and potential state failure in countries important to the United States, according to a U.S. intelligence community report last year.



"Between now and 2040, fresh water availability will not keep up with demand absent more effective management of water resources," the report said. "Water problems will hinder the ability of key countries to produce food and generate electricity."

About 780 million people around the world do not have access to clean drinking water, the United Nations reported last year.

"One of the areas that we're very concerned about in terms of global security is the access to clean and affordable drinking water," said Tom Notaro, Lockheed business manager for advanced materials. "As more and more countries become more developed ... access to that water for their daily lives is becoming more and more critical."

PRODUCTION CHALLENGE

Lockheed still faces a number of challenges in moving to production of filters made of graphene, a substance similar to the lead in pencils. Working with the thin material without tearing it is difficult, as is ramping up production to the size and scale needed. Engineers are still refining the process for making the holes.

It is not known whether Lockheed faces commercial competition in this area. But it is not the only one working on the technology.

Jeffrey Grossman, an associate professor at the Massachusetts Institute of Technology who has done research on graphene membranes for filtration, said he was not familiar with details of Lockheed's work. But he said finding a way to produce graphene sheets with nanometer-sized holes could produce a major advancement in desalination efficiency.

"If you can design a membrane that's completely different than what we use today, then there's a chance for more than two orders of magnitude (100 times) increase in the permeability of the membrane," Grossman said.

Stetson, who began working on the issue in 2007, said if the new filter material, known as Perforene, was compared to the thickness of a piece of paper, the nearest comparable filter for extracting salt from seawater would be the thickness of three reams of paper - more than half a foot thick.

"It looks like chicken wire under a microscope, if you could get an electron microscope picture of it," he said. "It's all little carbon atoms tied together in a diaphanous, smooth film that's beautiful and continuous. But it's one atom thick and it's a thousand time stronger than steel."

Thickness is one of the main factors that determines how much energy has to be used to force saltwater through a filter in the reverse osmosis process used for desalination today.

"The amount of work it takes to squeeze that water through the torturous path of today's best membranes is gone for Perforene," Stetson said. "It just literally pops right through because the membrane is thinner than the atoms it's filtering."

Notaro said Lockheed expects to have a prototype by the end of the year for a filter that could be used as a drop-in replacement for filters now used in reverse osmosis plants.

The company is looking for partners in the filter manufacturing arena to help it commercialize Perforene as a filter in the 2014-2015 time frame, he said.

Lockheed officials see other applications for Perforene as well, from dialysis in healthcare to cleaning chemicals from the water used in hydraulic fracturing, or "fracking," of oil and gas wells.

Hey this is pretty awesome.

[rhoenix]

Ah, fun with graphene again. Oh you magical leprechaun material, is there anything you won't do?

Just for fun, I looked up a list:

A survey of graphene applications:

Electrodes with very high surface area and very low electrical resistance. Researchers at Rice University have developed electrodes made from carbon nanotubes grown on graphene. The researchers first grow graphene on a metal substrate then grow carbon nanotubes on the graphene sheet. Because the base of each nanotube is bonded, atom to atom, to the graphene sheet the nanotube-graphene structure is essentially one molecule with a huge surface area.

Components with higher strength to weight ratios. Researchers have found that adding graphene to epoxy composites may result in stronger/stiffer components than epoxy composites using a similar weight of carbon nanotubes. Graphene appears to bond better to the polymers in the epoxy, allowing a more effective coupling of the graphene into the structure of the composite. This property could result in the manufacture of components with high strength to weight ratio for such uses as windmill blades or aircraft components.

Lower cost solar cells: Researchers have built a solar cell that uses graphene as a electrode while using buckyballs and carbon nanotubes to absorb light and generate electrons; making a solar cell composed only of carbon. The intention is to eliminate the need for higher cost materials, and complicated manufacturing techniques needed for conventional solar cells.

Transistors that operate at higher frequency. The ability to build high frequency transistors with graphene is possible because of the higher speed at which electrons in graphene move compared to electrons in silicon. Researchers are also developing lithography techniques that can be used to fabricate integrated circuits based on graphene.

Lower cost of display screens in mobile devices. Researchers have found that graphene can replace indium-based electrodes in organic light emitting diodes (OLED). These diodes are used in electronic device display screens which require low power consumption. The use of graphene instead of indium not only reduces the cost but eliminates the use of metals in the OLED, which may make devices easier to recycle.

Storing hydrogen for fuel cell powered cars. Researchers have prepared graphene layers to increase the binding energy of hydrogen to the graphene surface in a fuel tank, resulting in a higher amount of hydrogen storage and therefore a lighter weight fuel tank. This could help in the development of practical hydrogen fueled cars.

Sensors to diagnose diseases. These sensors are based upon graphene's large surface area and the fact that molecules that are sensitive to particular diseases can attach to the carbon atoms in graphene. For example, researchers have found that graphene, strands of DNA, and fluorescent molecules can be combined to diagnose diseases. A sensor is formed by attaching fluorescent molecules to single strand DNA and then attaching the DNA to graphene. When an identical single strand DNA combines with the strand on the graphene a double strand DNA if formed that floats off from the graphene, increasing the fluorescence level. This method results in a sensor that can detect the same DNA for a particular disease in a sample.

Lithium-ion batteries that recharge faster. These batteries use graphene on the surface of the anode surface. Defects in the graphene sheet (introduced using a heat treatment) provide pathways for the lithium ions to attach to the anode substate. Studies have shown that the time needed to recharge a battery using the graphene anode is much shorter than with conventional lithium-ion batteries.

Ultracapacitors with better performance than batteries. These ultracapacitiors store electrons on graphene sheets, taking advantage of the large surface of graphene to provide increase the electrical power that can be stored in the capacitor. Researchers are projecting that these ultracapacitors will have as much electrical storage capacity as lithium ion batteries but will be able to be recharged in minutes instead of hours.

Membranes for more efficient separation of gases. These membranes are made from sheets of graphene in which nanoscale pores have been created. Because graphene is only one atom thick researchers believe that gas separation will require less energy than thicker membranes.

Chemical sensors effective at detecting explosives. These sensors contain sheets of graphene in the form of a foam which changes resistance when low levels of vapors from chemicals, such as ammonia, is present.

The "Membranes for more efficient separation of gases" one is where the water purifier aspect comes from, from my understanding. Regardless, this is an awesome thing, and if it can be cheaply produced, then great.

[Josh]

Man, Lockheed's just popping shit out left and right. And they're claiming they'll have a prototype fusion reactor up in five years or so.

Makes you wonder if they really do have a UFO stashed away out there.

[General Havoc]

Maybe they got sick of waiting and built one?

[frigidmagi]

If anyone could do it... It would be Lockheed Martin.