October 24, 2003
Microfluidic Water Flow Generates Electricity

A large number of microchannels is needed to generate even a small amount of power.

Professors David Kwok and Larry Kostiuk squeezed a syringe of water through a two-centimetre wide glass disc cut by 480,000 holes, or "microchannels". When electrodes were attached at each end they were delighted to find they had generated just enough power to light a small bulb.

By itself this is not a new energy source. Some source of energy must be used to make the water flow.

Each channel is very small.

Thanks to a phenomenon called the electric double layer, when water flows through these 10-micron-diameter-wide channels, a positive charge is created at one end of the block and a negative charge at the other - just like a conventional battery.

The amount of electricity generated was very small.

They held a reservoir of water 30 centimetres above the array and allowed it to flow through the disc under hydrostatic pressure, generating a current of 1500 nanoamps in the process.

These researchers see both small scale and large scale applications for this approach.

The research team led by Professor Daniel Kwok and Professor Larry Kostiuk, of the University of Alberta, Edmonton, Canada, claim they have created a new source of clean non-polluting electric power with a variety of possible uses, ranging from powering small electronic devices to contributing to a national power grid.

Can this be useful for mobile phones?

"The applications in electronics and microelectronic devices are very exciting," says Kostiuk. "This technology could provide a new power source for devices such as mobile phones or calculators which could be charged up by pumping water to high pressure."

Their proposal to use their device as a battery really amounts to using highly pressurized water as the medium for storing energy. But that sounds impractical. The casing that holds the water would have to be strong enough to hold it under fairly high pressure. The water and the case would both add mass. Plus, the case has to have an incredibly strong valve that can open and close to let the highly pressurized water out as necessary. Fuel cells powered by a liquid hydrocarbon fuel seem like they'd have a better energy to mass ratio. Both compressed air and compressed fluids are being explored as energy storage methods in cars. But for something as lightweight as a cellphone compression of water has to compete against fuel cells and, perhaps further into the future, lithium polymer batteries.

There are of course lots of places where water flows already.

And might it one day power everything? "You'd need a really big area, like a coastal region," said Dr Kostiuk. "But then again, I guess, those are available, aren't they?" For a clean, free form of electricity, the answer must surely be yes.

One problem with using ocean water to generate electricity is that the water would have to be filtered before passing into the microchannels. But large scale manufacture of nanodevices might eventually provide the ability to use this approach to make devices that could generate electricity from waves or tide flow.

There is also the prediction of 1964 CMU professor Fletcher Osterle that this method of generating electricity will turn out to be very inefficient.

"Probably the reason no one carried on Osterle's work is that he concludes the efficiency can never be better than .04 percent. We haven't done much better than that so far, but we do think that we can do much better we have much better technologies today, like [microelectromechanical systems] than they did in the 1960s," said Kostiuk.

Water can already flow thru turbines at dams in order to generate electricity. Though turbines today are big things it will probably eventually be possible to make microelectromechanical systems (MEMS) turbines. Therefore MEMS microchannels are not the only imaginable approach for the use of MEMS devices to generate electricity from flowing water. MEMS turbines might turn out to be a more efficient than MEMS microchannels as a way to harness very small water flows.

Share |      Randall Parker, 2003 October 24 11:31 AM  Energy Electric Generators

Zoheb Hossain said at March 3, 2004 9:56 AM:

Dear sir,
Im zoheb hossain,Im male.Im 17 years old.I have make a new brand new project of produce electricity.Its no so costly.To do it i have everything that we need with out money.If u agree so i want to show u my secret project.Please sir try to contact with me.I live in bangladesh if u se my project then u will be aprisheadby it.I want to admit my project or sell my project in any country coz my family have dippendent in me so i havent any choice. and in my country a lots of marvalus brain will vaild day by day.coz they have the project but havent money,healp,and sponser,and legality.Coz our governt mot want to take there own project. please sir try to contact to my mail please

Mike Hills said at March 7, 2004 10:46 PM:

It's pretty much impossible to compress water. I don't think water will actually be compressed in this situation. When people typically refer to pressurized water tanks they are talking about tanks with an air bubble bladder. The air in the bladder is compressed by forcing water into the tank, the actual water doesn't compress. Just being picky about semantics.

sougandh said at June 10, 2004 9:14 AM:

Dear Sir,this is a discovery with a future by all means.as an electrical and electronics engineer, i have a few queries.1.could u tell me as to how much energy do these batteries produce,what is the amount of pressure required to push water through these channels,what is the amount of fluid required ,what is the type of nanomaterial used as channel,what are the future prospects,how is your study different from prof osterle.
2.where can i find the details such as the research paper on the net.please get me notes on the apparatus and the types of materials used if possible.
kindly help me i am very much interested

Nicklosh Meshatomb said at December 7, 2005 2:51 PM:

my name is nicklosh meshatomb so and i liv in Saudi Arabia but i wus wundoring if an site of hydroelectricr powur culd bee bilt at my cuntri becus powur is epxsenize here and mi famuly is havign hard timz here.
Sori if mi Englush is batd bud i onli juz lurnned for sum tym

Ms A Myers said at August 19, 2006 4:35 PM:

This is to Mr. Zoheb Hussain. I am interested in your project and I would like very much for you to contact me. My address is annamyers64@hotmail.co.uk

Abu Abdulrahman said at April 30, 2009 6:45 AM:

My name ; Abu Abdulrahman

i am looking for power saving techniques which will utilizing the water flow ( Sea water) through a channel

For those who can advice on the best way to utilize sea water flow to generate electricity in a channel( approx. 16 million M3 per day) with hight of 8 meter & wide 90 meter ,length 12 km

kindly advice which technology can be used & how much power we can generate also if we could have how much the cost of this project

who can add a value to this kindly send me on my e-mai shararih@hotmail.com


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