Desalination via graphene filtres

[marchesarosa]

Posted on March 17, 2013
Guest Post by Willis Eschenbach
wattsupwiththat.com/2013/03/17/energy-resources-money-and-technology/

I’ve made some statements lately that I’d like to reprise.

• There is never a shortage of resources. It’s a shortage of cheap enough energy to get the resources economically.

• Energy and money are inextricably linked.

• Making energy expensive hurts, impoverishes, and even kills the poor.

• Technology is not bulldozers. It’s getting more production using less energy.

People say, well, what about water? What if there’s a shortage of water? How does that relate to your statements above? You figure out how to manufacture water?

Graphene is a one-molecule-thick form of carbon, arranged in a hexagonal pattern.

I’d like to illustrate all four of these statements with a recent news article, from Reuters:

Pentagon weapons-maker finds method for cheap, clean water

(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.

As you might guess, they make it out of graphene.

“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.”

Damn … a factor of a hundred? Two orders of magnitude less energy required? Are you aware what that will do?

Well … without cheap energy, it won’t do much at all, will it? … it takes a large amount of energy to pump the seawater through the reverse osmosis filters, even new graphene filters.

But with cheap energy? It can make the deserts bloom, quite literally. Israel’s doing it now, they are currently desalinating about three hundred million (300,000,0000, cubic metres of water per year. two hundred billion gallons, 200,000,000,000). And plants are now under construction to more than double that amount.

How much water is that? Well, when the new Israeli plants are at full capacity it will be enough to cover all of Israel’s current agricultural land with about 6″ (15 cm) of water. And they’re already doing it at a reasonable cost, even before the latest development. Right now, it’s about five gallons for one cent ($0.01).



Figure 2. Cost per cubic metre (black) for desalinated water around the world. I have added the cost per 100 US gallons in blue. The four outlined plants are in Israel.

Now, with the new graphene filters, the cost of water should be dropping, perhaps even by a factor of ten, for people from Algeria and Cyprus to Trinidad and Israel. And since this is just a filter and can be made in any shape, it can be made as a pin-to-pin replacement for filters in existing desalination plants. This can only be good news for the poor of the world.

Let me look at all of that discussion of desalination in terms of my statements reprised above:

• Technology is not bulldozers. It’s getting more production using less energy.

This is at the heart of the new development of the graphene filter for the reverse osmosis desalination of seawater.

• Making energy expensive hurts, impoverishes, and even kills the poor.

If a country has to pay twice as much for its energy, it will pay twice as much for its water. This hurts everyone, particularly the poor.

• Energy and money are inextricably linked.

The cost of the water is a function of the cost of energy.

• There is never a shortage of resources. It’s a shortage of cheap enough energy to get the resources economically.

If energy is cheap, then with technology many, many things are possible … including using endless seawater to turn the deserts green. On the other hand, if energy is expensive, resources are no longer economical, water costs more, and people suffer.

That’s all,

w.

[jonjel]

One reason for needing desalination plant is that Isreal have taken the Jordan down to a mere trickle. I have seen it and was staggerd that it is still a beutiful river in the upper reaches and little more than a ditch in the lower parts.

[marchesarosa]

I doubt if the Jordan alone could have supplied all the water resources necessary for modern agriculture in the region, AND the demands of a growing westernised population, jonjel. Desalination is necessary.

If what willis wrote is correct the cost of desalination can be brought down markedly courtesy of graphene filters and cheap natural gas and to everyone's benefit. Israel could probably also sell it to land-locked Jordan and the West Bank unless Saudi Arabia piped it in first free of charge! Even Gaza could get in on the water desalination act with a little investment from its many friends!

[jonjel]

One problem is that the artesian basin has been decimated in the area, which is part of the reason the Jordan is in such a perilous state.

I have said for some time that the next war in that area will be over water, not land.

But maybe cheap desalination is the answer. That and knocking a few dumb skulls together.

[mrsonde]

Mar 18, 2013 13:40:52 GMT 1 jonjel said:

One reason for needing desalination plant is that Isreal have taken the Jordan down to a mere trickle. I have seen it and was staggerd that it is still a beutiful river in the upper reaches and little more than a ditch in the lower parts.

Jordan, Syria and Lebanon are more responsible than Israel for reducing the Jordan. In fact, Israel is now returning water to the river, rather than taking it. 85% of Israel's water is desalinated - 75% of Jordan's is taken from the river. Israel is thus supplying a significant proportion of Jordanian and Syrian water needs, free of charge - and the NWC has stated this will continue for decades, until Israel has returned all the water they've ever removed.

But who cares about the facts where the evil Zionists are concerned?

[mrsonde]

Mar 18, 2013 17:45:07 GMT 1 jonjel said:

One problem is that the artesian basin has been decimated in the area, which is part of the reason the Jordan is in such a perilous state.

I have said for some time that the next war in that area will be over water, not land.

The wars have always been about water, not land.

[principled]

Marchesa
Just read this about Graphene in DM. I know it's not the best scientific journal but...
Anyway, I am mystified. As stated in the article, the density of the Graphene Aerogel at 0.16g/l is less than that of helium (0.1786g/l), so give that it is less dense why does it not float in the air?
I must be missing something, somewhere. Explanations anyone?
www.dailymail.co.uk/sciencetech/article-2296223/Lightest-material-Graphene-aerogel-balanced-atop-petals-flower.html
P

[marchesarosa]

(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.

(Editing by Warren Strobel and Jackie Frank)
www.reuters.com/article/2013/03/13/us-usa-desalination-idUSBRE92C05720130313

[mrsonde]

A couple of things that puzzle me about that report. First, you posted a lecture a year or so back (I can't find it) from, I think, Northwestern Uni, where a process for separating ions and pollutants from water was briefly outlined. This exploited the fact that water structures itself using a suitable crystallising bed as a substrate. A double pipe exploiting this elementary fact and centrifrugal force separates water molecules from other heavier constituents, allowing the passage of pure water but not its contaminants, using no energy whatever.

Second - efficient desalination plants use hydraulic ram pumps to impel its water through its filters. These require no generated energy input at all, but work by gravity: you simply place your pump at a lower depth than your source, and the valve will pump the water to any height required (with tremendous force). No additional energy is required, and very little maintenance - the valve needs to be refurbished every decade or so (it's no different from the Coventry or Portsmouth valves in a cold water storage tank.)

[mrsonde]

Incidentally, Marchesa, why haven't you posted that excellent Matt Ridley lecture you put up on WHS? I think everyone should have the pleasure of seeing that - in fact, I think it should be compulsory viewing, in every school throughout the Western world. First class would be every journalist and executive working for the BBC.

[marchesarosa]

I thought WHs needed the information from Ridley more than the folk here, Nick!

Which Ridley talk are you referring to? I will post it here.

[mrsonde]

The one you posted the day before yesterday! What's wrong with you?!

[alancalverd]

All very impressive except for the physics, alas.

A one nanometer hole won't separate anything from anything useful. The water molecule is about 0.14 nm in diameter and the sodium and chloride ions are not much larger (salt does not exist as "molecules" in solution). So they will all happily pass through a nanometer graphene filter, even if one existed.

[fascinating]

Thank you Alan, those facts passed me by; even though I know that atoms are about a tenth of a nanometer in diameter (many somewhat larger), and that of course a salt molecule breaks up in solution, I didn't twig that a mesh with nanometer holes isn't going to do anything to filter salt from water! So what is this all about I wonder?

[marchesarosa]

When water molecules (red and white) and sodium and chlorine ions (green and purple) in saltwater, on the right, encounter a sheet of graphene (pale blue, center) perforated by holes of the right size, the water passes through (left side), but the sodium and chlorine of the salt are blocked.

Graphic: David Cohen-Tanugi


web.mit.edu/newsoffice/2012/graphene-water-desalination-0702.html