Monday, March 25, 2013

Perforated graphene and desalination

The two greatest challenges facing humanity concern 1) capturing a reliable supply of energy from the sun; and 2) ensure that everyone has a reliable and abundant supply of clean fresh water.  I write about (1) energy almost all the time because deep down I believe that with enough energy, most—if not all—the other problems can be solved.  But that does NOT make the water problem any less serious.

Since the earth is 71% covered in water, the only reason water supplies could ever be a problem is that the overwhelming majority of it is too salty to drink or grow crops.  And until now, the existing methods for desalination have been energy intensive and hence, hideously expensive.  But if the claims in the following story are true, this is about to change radically.

It's hard to say which part of this story is more interesting—the fact that the inventor of the new technology is a defense contractor apparently beating some swords into plowshares, that the new filtering mechanism employs graphene which is so new, the researchers who figured it out only got their Nobels in 2010, or that the new filters are made of carbon—something we have in excess.  IF this works, this is the single most hopeful news I have seen in my adult life.  It is beyond merely significant.

And if it works, I will feel vindicated that I was right to focus on energy issues.  Because when it comes to energy, it is highly unlikely there will ever be a magic bullet that solves the problems as neatly as perforated graphene.

Lockheed Martin Says This Desalination Technology Is An Industry Game-Changer

Dina Spector | Mar. 22, 2013

The latest technology for removing salt from seawater, developed by Lockheed Martin, will be a game-changer for the industry, according to Ray O. Johnson, senior vice president and chief technology officer of the jet and weapons manufacturer.

Desalination technology is used in regions of the world, particularly developing countries, where fresh water is not available. Water from oceans or rivers is diverted into treatment plants where the salt is removed and clean drinking water is produced through a process called reverse osmosis.

Imagine a tank with seawater on one side and pure water on the other, separated by a filter with billions of tiny holes. Lots of pressure on the salty side pushes water through faster than the salt, so fresh water comes out the other end.

The problem is that current filters use plastic polymers that require an immense of amount of energy (800 to 1,000 pounds per square inch of pressure) to push water through.

Lockeed has developed a special material that doesn't need as much energy to drag water through the filter.

Graphene is a substance made of pure carbon. Carbon atoms are arranged in a regular hexagonal or honeycomb pattern in a one-atom thick sheet.This special material is a film of a special structure of carbon, a honeycomb lattice called graphene. Because of its structure the sheet is dotted with holes that are one nanometer or less. These holes between carbon atoms trap the salt and other impurities.

Graphene researchers won the Nobel Prize in Physics in 2010 for developing the wonder-material.

In addition, the film is super thin — just a single atom thick — so that the water simply "pops through the very very small holes that we make in the graphene and leaves the salt behind," John Stetson, the chief technologist at Lockheed for this initiative told Business Insider.

Lockheed anticipates that their filters will be able to provide clean drinking water "at a fraction of the cost of industry-standard reverse osmosis systems," their press release says. Water-poor regions of the world will be the first to benefit.

The perforated graphene is aptly called Perforene. Lockheed has the U.S. Patent on this technology and is currently pumping out "pretty big quantities of it" at Lockheed's advanced technology center in Palo Alto, California, according to Stetson.

The Perforene has a smoky grey color film that is translucent, even though its carbon, because it is so thin. It's also about 1,000 times stronger than steel, but still has a permeability that is about 100 times greater than the best competitive membrane out in the market, said Stetson.

Perforene isn't a game-changer, yet. Lockheed is still in prototype stage. One challenge is figuring out how to scale up production. Graphene is cheap but it's very delicate because of its thinness, also making it difficult to transfer.

Stetson says Lockheed is targeting to have a prototype to test in a reverse osmosis plant by 2014 or 2015, where they would simply be able to "plug in" the Peforene to replace the existing filter.

The great news is that this technology is not just limited to desalination plants. It can potentially be used for pharmaceutical filtration, dialysis, and gas separation, to a name a few. more

1 comment:

  1. The World Water Desalination industry to grow at a Compounded Annual Growth Rate of 9.51 % over the period 2012-16. One of the key factors contributing industry development is the need for safe water. The International Water Desalination industry has also been seeing increased government projects in the Water industry. However, the possibility of water desalination putting the ocean ecosystem at risk could pose a challenge to the development of this market.