Desalination attempts for converting seawater to fresh, drinkable water are on the rise. The decision to pursue or not pursue desalination projects is a ballot item right now in Santa Cruz, Calif., the city nearest to the town I live in. It's a pressing issue in many parts of the world, including here where the aquifer has been shrinking for a couple of decades.
A new composite material invented by researchers at the Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM) may help bring down the cost of some desalination plants. These processing plants require highly specialized, expensive infrastructure, including pipelines made of titanium and various forms of high-alloy steel that resist the corrosive action of salt water. Although pipeline cost isn't the only expense, expense in general is one of the objections to desalination.
A new composite material for saltwater desalination plant pipelines may help bring down the cost of the process. (Source: Fraunhofer IFAM)
The most common desalination method is multi-stage flash distillation, a form of thermal distillation. In thermal distillation desalination methods, the pipes must also be heat-resistant, since this process requires them to be heated until water sprayed on them boils and evaporates, leaving behind salt and chemical residues. Pipes in desalination plants must therefore be highly durable, corrosion-resistant, heat-resistant, and long-lasting. They must also have a surface that can be easily coated with seawater, so the fresh water evaporates correctly.
The Fraunhofer IFAM's polymer composite conducts heat and can be produced in continuous lengths, which the researchers say will make it less expensive than the specialty metals it can replace. Although a plastic, the composite conducts heat because it contains copper microfibers, about 50 percent by volume. "This does not change the processing properties of the composite, and it can still be processed as any other polymer would," said Arne Haberkorn, an IFAM scientist, in a press release.
The material has been developed, and the researchers exhibited it at the Composites Europe 2012 trade show in Dusseldorf, Germany, October 9 to 11. Their next step is to optimize its thermal conductivity by testing it in a pilot seawater desalination plant.
During testing, they expect to measure the composite's thermal conductivity, observe how much microorganism-based coating forms on the pipes, and see to what extent the pipes corrode in a salty environment. In the pilot plant's evaporation process, hot gas heated to 70C will run through the pipelines. This temperature is lower than some of the highest temperatures in multi-stage flash distillation, which can run up to 120C. The benefit of lower temperatures is that the material doesn't corrode as quickly, there's less deposit buildup on the pipes, and the inside and outside pressure differential is much less. This results in pipes that last longer and a process that requires less maintenance.
Very interesting development, Ann. Providing a more economical way to attack the desalination process could really make a big difference in pushing more of these projects to the fore and help them gain a foothold in developing areas that are really desparate for fresh water sources.
When reading of flash-tube boilers I envisioned tubes heated to several hundred or more degrees, not 70-130. The concept of having water spray and evaporated steam in close proximity without excessive mixing is interesting. I wonder if flash-tube could be economically superior to Reverse Osmosis? Certainly the next 30 or so years will see the need for many more water purification methods.
Reverse osmosis and other membrane technologies are the methods I'm more familiar with and have heard mentioned more often, so I was surprised to discover that thermal distillation is the technology used in the majority of installations. Although RO presumably uses somewhat less energy, both processes are quite intensive energy users. Re temperatures, thermal distillation is a form of vacuum distillation, which allows water to boil at a lower than normal temperature due to lower pressure. The Wikipedia article on desal is helpful.
I've been watching the desal controversy for several years as it's been debated locally. Although it's not the only one, infrastructure cost is definitely one of the problems that must be overcome.
I think often problems like this are solved by going through a set of steps where the technology to solve the problem is solved and then economics come in and are improved and then the technology to solve the problem is improved and then the economics come in. It's a cycle of improvement that ends up developing a final solution. It's fun for me to watch because it just shows the never give up attitude of engineers.
Desalinization isn't a good long term solution. It's been used in Israel for years for crop irrigation. The strawberries in Israel today aren't nearly as delicious or nutritious as they were decades ago. I think the berries are telling us something. Legalizing and building infrastructure to utilize grey water would offer a longer solution for potable water shortages.
This may be easily used for manufacturing and energy creation. Many newer processes seem to involve massive amounts of fresh water.
Thanks, Nadine. Your POV is held by many here, regarding using other options such as graywater conversion and conservation. The problem with conservation in Santa Cruz County is that we've done just about as much as we can, short of graywater conversion both public and private: our water usage rates here are very low already compared to other areas of the US. And why we haven't done graywater conversion more on a public scale, I don't know--it seems so obvious.
There are very strict restrictions on grey water usage here in California. Regulations loosened up a little a few years ago. Many people in the Bay Area promote grey water usage, and sell how-to kits and books. Technically, some of the movement is breaking the law but it's moving the debate in a positve direction.
My POV is based in research and observation. Desalinization seems like a good idea but only offers short term relief.
Nadine, I agree about graywater usage. I live in a hotbed of it here in Santa Cruz county. If it wasn't for the expense, we would have installed one a long time ago on our own property. I still plan to, but it's still behind other homeowner fixup priorities. That's a big part of the problem in leaving it up to the private sector, i.e., homeowners. I wish there were incentives like tax deductions, such as there have been for solar.
I do agree with the idea of tax breaks to encourage developement of technologies that make things better or cheaper. But I struggle with tax breaks for homeowners just to put in the solutions. I'd rather see the government spending money to make things more affordable, rather than giving us money to use products that aren't financially viable right now.
jmiller, personally I'd rather see technology get implemented sooner rather than later for several reasons: makes more people aware of it, gets accepted faster, and helps bring down costs sooner, among them. Government tax breaks can help all these happen. At least using our current economic model, it's higher volumes in manufacturing that can help to make things more affordable.
I'd like to see technology implemented as soon as possible. But I don't have a lot of faith in our current economic model. I struggle to support continual government funding to in some cases force development in an area that might not be viable.
So why aren't the strawberries as good. Is the water quality not as good? Did some of the salt not get our of the water? I agree with the idea of using grey water because that would be available in a lot more of the middle United States. But I'm also curious with some of the problems being experienced with current systems.
I haven't read anything definitive about why the strawberries aren't as tasty or nutritious. But just taking the salt out doesn't turn seawater into freshwater. It may be drinkable but it's not the same.
Maybe a Gadget Freak will come up with something for grey water or capturing rain water for the lawn.
Beth, we know that eventhough 2/3rd of earth is covered by water, most part of the world still have scarcity of drinking/fresh water. So the best option to bridge the gap is purification or desalination of sea water. Most of such projects required huge investment and complex technology/machinery for purifying the salt water. A new more economical and simple technology has yet to be discovered and I think these new technology may comes under that category.
I like articles like this that show opportunities for engineers to come through with a way to improve life in a significant way, not just make a better mouse trap.
jmiller, thanks for the comment--I enjoy reporting and writing articles that showcase engineers who've designed something with innovation and ingenuity, which can make major improvements in our lives, too.
It would seem that removing the salt and other minerals froom seawater would be the preferred method, not only because of the magnesium recovered, but because sea water is an easy to get resource that we won't be in any danger of running out of. If the berries are different after a few years it is probably because of cost being taken out of the growing process, not because of the water. What quality reduction has been implemented to increase profits?
Of course desalination does need a lot of energy, I don't know any way around that, one other option is for people to not live in that area that has no water. Did anybody ever stop and consider that some places that seem uninhabitable ARE UNINHABITABLE? Even if some developer puts houses there?
REmember the Bob Dylan quote: "One should never be where one does not belong"? It is also appropriate for areas without water.
The problem is that while we can make potable water out of seawater, we can't make the energy to do the process.
William, I think that's an excellent point: some areas are simply not inhabitable by a certain number of people after a specific threshold has been passed, without either importing huge amounts of water, such as in Los Angeles, or without needing a huge, expensive, artificial infrastructure of some kind. We have come to think such an infrastructure is the norm, but it's quite recent in human history. And thanks for quoting Bob Dylan :)
I do agree there are areas we shouldn't be. However, it's interesting how many people choose to live there. In the case of a lot of cities, more and more people are living in a n area that just can't support the population. In the case of some cities, we have literally built in areas below sea level. In the end, sometimes, I think every time we build a solution to a problem. The world finds a way to build a bigger idiot.
Ann, I know in most of the Arab countries, they are distilling the sea water for residential purpose other than drinking. Am not sure about the technology they are using for this purification, but I heard that it's a multi stage purification, where water is evaporating to remove the salt content. In such cases I think the new technology seems to be superior and affordable.
Mydesign, that's a distillation process you describe, so it sounds like the majority form of desalination, the one I cover here. I'd be interested to know more about what exact processes are being used and what challenges, obstacles, problems, etc. the Arab countries have encountered. I'm also very curious about reverse osmosis, the much less often used method, and wonder why it isn't used more often.
Ann, RO water purifications are commonly implemented with house hold water purifiers. It's a five stage purification method and so far I had not seen it with any large scale implementation. If my knowledge is right, Arab countries are implemented multi stage flash distillation method, where water is heating and reheating multiple times. Now there are some new technologies like osmosis technologies (Reverse, Forward), Electro dialysis and Distillation methods like Thermal Distillation, Multi-Effect distillation etc are implemented in certain countries.
Very interesting article, Ann. Living in the Midwest on the shores of one of the largest bodies of fresh water in the world, I didn't have a lot of background in how desalination is accomplished. Using the method you described, I would assume that they materials being used would have to be rather "slippery" too. If you are spraying salt water on them specifically to cause steam and leave the salt and contaiminate behind, I would think that the pipes would be covered in a relatively short period of time...either that or there is a good method for continual cleaning.
Thanks, Jack. The surface material must be both sticky and slippery, so the chemical- and salt-laden seawater stays on only long enough to evaporate completely and efficiently, but no longer. Ideally, it also must shed deposits relatively easily. There's no continual cleaning here: regular maintenance is required, as with metal, but lower process temperatures allowed by the material will help residues build up more slowly.
Inspired by the hooks a parasitic worm uses to penetrate its host's intestines, the Karp Lab has invented a flexible adhesive patch covered with microneedles that adheres well to wet, soft tissues, but doesn't cause damage when removed.
Engineers at the University of California, San Diego are designing a robotic arm that takes inspiration from the loose, flexible, yet very strong structure of the armored plates on a seahorse's tail.
Researchers at the Missouri University of Science & Technology have designed a new nanoscale material that can transmit light faster than the 186,000 miles per second it usually takes to travel through air.
It has often been said that as California goes, so goes the nation. This spring, the state's wind power is setting energy generation records and solar energy generation is expected to rise sharply during the second half of 2013.
From Dell / Intel® New Paradigms in Design Work Scott Hamilton, vertical market strategist for Dell Precision workstations, 5/2/2013 3
Early in my career, I worked as a draftsman and remember the days of drawing on vellum with numbered pencils and Mylar with plastic lead. This was a fun experience in the sense that I ...
I've been using workstations for more than 10 years and love finding ways to get more performance from my system. With demanding professional applications that require more power each ...
A lasting memory from my first job as an engineer in an auto assembly plant is standing on hard concrete at six in the morning, vending-machine coffee clutched in hand, listening to ...
A quick look into the merger of two powerhouse 3D printing OEMs and the new leader in rapid prototyping solutions, Stratasys. The industrial revolution is now led by 3D printing and engineers are given the opportunity to fully maximize their design capabilities, reduce their time-to-market and functionally test prototypes cheaper, faster and easier. Bruce Bradshaw, Director of Marketing in North America, will explore the large product offering and variety of materials that will help CAD designers articulate their product design with actual, physical prototypes. This broadcast will dive deep into technical information including application specific stories from real world customers and their experiences with 3D printing. 3D Printing is
To save this item to your list of favorite Design News content so you can find it later in your Profile page, click the "Save It" button next to the item.
If you found this interesting or useful, please use the links to the services below to share it with other readers. You will need a free account with each service to share an item via that service.
Tweet This
1 
