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.