Alloy could help provide water and power in remote areas
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Researchers have developed an aluminium alloy that could be used in a new type of mobile technology to convert non-potable water into drinking water while also extracting hydrogen to generate electricity.
Such a technology might be used to provide power and drinking water to villages and also for military operations, said Jerry Woodall, a Purdue University distinguished professor of electrical and computer engineering.
The alloy contains aluminium, gallium, indium and tin. Immersing the alloy in fresh water or salt water causes a spontaneous reaction, splitting the water into hydrogen and oxygen molecules. The hydrogen could then be fed to a fuel cell to generate electricity, producing water in the form of steam as a by-product, Woodall explained.
‘The steam would kill any bacteria contained in the water, and then it would condense to purified water,’ he said. ‘So, you are converting undrinkable water to drinking water.’
Because the technology works with salt water, it might have marine applications, such as powering boats and robotic underwater vehicles. The technology also might be used to desalinate water, added Woodall, who is working with doctoral student Go Choi.
Woodall envisions a new portable technology for regions that are not connected to a power grid.
‘There is a big need for this sort of technology in places lacking connectivity to a power grid and where potable water is in short supply,’ he said.
‘Because aluminium is a low-cost, non-hazardous metal that is the third most abundant metal on Earth, this technology promises to enable a global-scale potable water and power technology, especially for off-grid and remote locations.’
The potable water could be produced for about $1 (£0.60) per gallon, and electricity could be generated for about 35¢ per kilowatt hour of energy.
‘There is no other technology to compare it against, economically, but it’s obvious that 34¢ per kilowatt hour is cheap compared with building a power plant and installing power lines, especially in remote areas,’ said Woodall.
The unit, including the alloy, the reactor and fuel cell, could weigh less than 100lb.
‘You could drop the alloy, a small reaction vessel and a fuel cell into a remote area via parachute,’ Woodall said. ‘Then the reactor could be assembled along with the fuel cell. The polluted water or the seawater would be added to the reactor and the reaction converts the aluminium and water into aluminium hydroxide, heat and hydrogen gas on demand.’
The aluminium hydroxide waste is non-toxic and could be disposed of in a landfill.
The researchers have a design but have not built a prototype for the design, which has a patent pending.
This diagram illustrates the potential uses of a new theoretical type of mobile technology that would use an aluminium alloy to convert non-potable water into drinking water while also extracting hydrogen to generate electricity. Such a lightweight, portable system might be used to provide power and drinking water to villages and also for military operations. (Jerry Woodall)
Readers' comments (10)
Dave Bennett | 4 May 2011 2:37 pm
It looks like a lot of energy (and resources and money) goes into the front end production of the equipment - what will the capital costs be compared to capital and operating costs using a local renewable heat source (burning animal dung/dry vegetable matter etc) and heating water and condensing it?
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David Mioduski | 4 May 2011 3:56 pm
THere are a lot of unanswered questions in my mind that this article creates. Maybe it's just an incomplete explanation. How much of the alloy is needed to make the reaction and how long does that amount of material last. How much heat will it produce and for how long? How much water will it generate at the same time? How about other contaminates (chemicals, oil gas ect.) that may be in the water other than bacterial - what will filter them out? They can vaporize and condense as well.
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Mr. Norman A. Nadeau | 5 May 2011 3:17 pm
This is an excellent breakthrough in fuel cell technology providing remote power with simple fuel cell technology, some solar and or wind technology should also be implemented as a back up. I have lots of third world contatcs that could and will use this technology.
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Prem Nandlal | 6 May 2011 2:27 am
Can you imagine the economic advantage this technology can offer to countries like Guayna with billions of gallons of fresh water over the K falls per month. The hydrogen produced can be the catalyst for petrochemical plants.
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Sumit Majumdar | 6 May 2011 5:28 am
Clean technology and a great breakthrough with numerous applications. Hope it does not take a lifetime to benefit mankind.
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V.Senthilkumar | 6 May 2011 12:20 pm
This is a wonderful beginning towards a clean technology which might, in future help the developing and underdeveloped world.
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Jim Edmunds | 7 May 2011 10:21 pm
I fully agree with David M above - the article is very light on scientific explanation. How many litres of contaminated water can the alloy 'treat' before being rendered inactive? Al is common, but the other key elements are less so - is this an issue? How does it actually work? Is form an important factor?
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R | 9 May 2011 7:36 am
Electricity is used to produce aluminium and the alloy process uses some more energy. Second law of thermodynamics limits the output power to below unity.
This process of power generation will perhaps be limited to remote generation.
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John Douglas | 9 May 2011 1:53 pm
The emphasis in the comments has been on the power side, while the article makes considerable play of the potability of the product. Beware the health issues involved with this as a main source of water: distilled water is not good for you. The product will need mineralising:
1. to make it palatable,
2. to make it safe and healthy,
3. to prevent it from corroding the distribution infrastructure.
The easiest way is to run the de-mineralised water through a limestone filter but this is becoming more demanding in process terms as well as requiring yet more energy input.
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Anonymous | 13 May 2011 0:39 am
Sheesh. You make aluminum from aluminum hydroxide and electricity. All these guys are doing is reversing the reaction. Similar proposals have been made for decades. Read the literature.
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