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Hydro-electric power with a difference

Natalie Solent links to news of this new discovery:

A team of researchers led by Dr. Daniel Kwok and Dr. Larry Kostiuk in the Faculty of Engineering at the University of Alberta has discovered a new way of generating electric power from flowing water.

When a liquid such as water is passed through a small channel, a physical phenomenon called charge separation occurs. The surface of the channel becomes ionically charged and opposite-charged ions in the liquid are attracted to it.

At the same time, like-charged ions are repelled from the surface. This results in a thin liquid layer with a net charge. This region, known as the Electric Double Layer (EDL), ranges from several nanometres to a few micrometres thick.

To harness this phenomenon, the research team constructed a microchannel with a diameter similar to the EDL itself and then forced the liquid through the channel. This resulted in only one type of ion in the EDL being transported downstream, creating a current and hence a voltage difference across the ends of the channel.

An external electric circuit was constructed by placing electrodes at the ends of the channel, and electrical energy was extracted from the device as current flowed between the electrodes.

I am impressed, I think. Or I will be as soon as I am convinced that this is not just wishful thinking in techno-babble.

I am not so impressed by the Calgary Sun’s reporting of the story. They regard the “response from the international community” as being more significant than the workings of the invention itself, which is to get it the wrong way around, I think. But after they have given us a few paragraphs about all the phone-calls and e-mails that have already flown around concerning this new gadget, they too get around to describing what it does…

With the help of two graduate students, the two professors were able to light a small bulb by simply squeezing a syringe of ordinary tap water through a glass “filter” with microscopic-sized holes they call microchannels.

They invented their “electrokinetic” water battery by harnessing the natural energy that is created on a very tiny scale when a flowing liquid meets a solid surface, creating an electrical charge. Water forced through a microchannel results in the movement of positive and negatives ions in such a way that one end becomes positive and the other negative.

…and how significant it might be:

The inventors are particularly excited by the fact the electricity is produced cleanly and involves no moving parts.

The discovery could in a matter of years lead to batteries for everyday items such as cellphones and calculators being powered by pressurized water.

The Green Movement will be appalled. How can they be expected to prevent all forms of technological progress and take humanity back to the Stone Age, if even Canadians are doing stuff like this?

More seriously, is this the technology that might finally make electric cars a serious proposition?

And: what kind of water is involved here? Does it get used up by the process? Will salt water suffice? Tap water? In fifty years time will the World Economy be yanked this way and that by WPEC?

Time for the Samizdata commentariat to do their stuff.

26 comments to Hydro-electric power with a difference

  • Ron

    How long before the microchannels get bunged up with calcium scale?

  • Andrew Duffin

    “How long before the microchannels get bunged up with calcium scale?”

    Well quite a long time if you locate the machine in a soft water area.

    But that’s the wrong question.

    The right question is how much energy had to be put IN (in pressurising the water and making it flow through a narrow orifice) relative to the amount that came OUT?

    I guess the answers are “lots” and “a little”.

    I also guess that although improvements will be made, this is just another perpetual motion machine.

  • Well, it’s keen and all that, but it’s hardly an energy source. It’s going to take more energy to do the pumping than you’ll get back out. So unless you get the energy for “free” (as for example at the bottom of a dam) it’s not clear to me what can be done with this.

    But the exploitation of most discoveries is not obvious at first, so I’m still hoping something comes of this.

  • Brian Micklethwait

    Perpetual motion machine? Maybe not. I’m no techie, but isn’t the problem with batteries not a shortage of energy in the whole world, but the extreme difficulty of packing even some of that energy into a portable battery? Even if it used twice as much energy of the more usual sort to power up a water battery, that could still be a terrific deal for all concerned.

    What matters is surely how much energy you can get into a small space, rather than just the energy economics of the entire deal.

    Sorry if that’s rubbish, but that’s how it seems to very-un-tchno me.

  • Patrick W

    I think both Brian and Andrew are right – but looking at different aspects of the issue.

    Quite clearly this process is not a solution to the issue of generating power. It will require more energy to be put in than you get out. And where there is a free head of water pressure (dams) it may be less efficient than turbines or (more relevantly) incapable of generating sufficient wattage. It’s a bit like the issue of hydrogen – not an energy source but a fuel or energy storage medium.

    However it is possible to think of applications where low level electrical power is needed and a bit of physical brute force can be easily applied. I myself live in Africa and own a clockwork wind-up torch (once wound it shines brightly for about 10 minutes). I can imagine torches, radios, PCs, etc could be powered by filling with water into some sort of piston and then compressing with a powerful spring. I don’t know how much water flow is needed to generate how much power though. If you need a litre a minute going through the tiniest practicable appertures – say – this is not going to go anywhere.

  • There was a much better report on this in the Times yesterday. They had a diagram showing how it works and everything.

  • Jonathan L

    I think Patrick W has the right idea. This is a new form of clockwork mechanism.

  • speedwell

    I think Patrick W. is wrong. (I say this in the nicest possible way.) This IS a solution. Just one solution, and probably not practical for most users in most situations (though we might all be real surprised someday).

    But somewhere out there exists the problem for which this is the only solution, or an idea that up till now could not be realized without an application derived from this mechanism.

  • Dave O'Neill

    The technology looks interesting. I can’t see it scaling to any large amperage application like a car, but for laptops and phones it might give the proposed thermo-couple fuel cells a run of their money.

    I’d assume something with a closed cycle of distilled water powered by a small CO2 cylinder or the like for the pressure. It would certainly be faster and easier to “charge” than a coventional Ni-Cd or Li-Na battery.

    I’d be concerned about the pressure actually needed to force the water through the power cell. But as a generator with no moving parts it has to be quite interesting for a number of low amperage applications.

  • WD

    Is this any different than the self potential, spontaneous potential, or streaming potential phenomena that the Petroleum industry routinely measures in boreholes? Basically, at the boundary between sand and shales a measurable potential exists. There is also a surface technique that’s commonly used to detect water flow, say from under dams that uses the same idea that flowing water through microchannels in soil creates a measurable voltage. In other words, is there anything really “new” here.

  • Dave O'Neill

    I read in one report that they wanted to explore a way of taking current from porous rock features.

  • WD,

    No, there’s no new phenomenon here. As I understand it, though, this is the first time the phenomenon has been harnessed, rather than merely observed.


    You’re right: the issue is the portability of the energy, not efficiency.

    I think we all need to prepare ourselves for the horrifying possibility that the mobile phones of the future will have little holes for their users to spit into.

  • R. C. Dean

    mobile phones of the future will have little holes for their users to spit into.

    Mine already does. Its called the “microphone.” 😉

  • Peter Melia

    Suppose a robust version was made, and incorporated into sea walls. Then the power could be used for warning lights etc.
    Air is a fluid. Perhaps someone can establish if the trick works with airflow. Then we have an entirely new measuring device, rate of airflow gives power.
    Peter Melia

  • Kevin L. Connors

    Not my engineering bailywick here. But intuition tells me thatt the frictionfriction losses from pushing the water through millions of “microchannels” is going to be a hell of a lot greater than the losses from just having the water spin a turbine.

    It’s all moot anyway. Shouldn’t that crack-pot with the “scalar energy” device be introducing his 2.5 kw home genertor any time now?

  • Vic


    If you’re referring to who I think you’re referring to – he’s apparently on the run now with his investors money.

    I haven’t got the link on hand, but the fellow who several years ago demonstrated a mystery-powered Delorean at some Nascar track, and who also claimed to be running his house off of a black-box version of same has now absconded with his investors cash…

    The post I’d read was some gnashing of teeth by his ex-partner…


  • This is certainly not a perpetual motion machine and there’s no claim of that. It clearly converts kinetic energy to electricity, which doesn’t seem very implausible.

    This may turn out to be more important for nanotech than large scale power generation.

    The no moving parts is a big deal. Even if it’s less directly efficient, you may well make it up on maintenance if it’s not too far off.

    Also, depending on how much pressure (as opposed to energy) is needed, you might be able to get hydropower without having to build huge dams. That’d save you some money.

  • Kevin L. Connors

    If you are takling about micropower applications, the piezoelectric effect is quite well proven.

  • The Wobbly Guy

    The electric double layer effect has been well documented in various chemical analytical techniques like Capillary Electrophoresis and volttametry.

    This is the first I’ve heard of it as a power source though.

    There’s a series of equations that defines the thickness of the double layer, which often requires a specific surface, like Si-OH molecules, to enhance the effect. Obviously, the water has to contain a certain concentration of ion charges as well; however, it was found that higher concentrations lead to thinner double layers.

    Efficiency wise, although I’m not an engineer, I think it’ll be pretty low. As for its portability, I’ll point that that this is about energy generation, not storage, which is where the portability issue is more pertinent.

  • Ed

    There’s probably a great many applications for something like this.

    Especially as it requires no moving parts and involves moving fluids. I can see some possible applications in the medical field. Perhaps embedded devices that are powered by the electrical energy generated from the flow of blood. This would enable devices to avoid having be charged by external sources.

    Another might be devices in space. Perhaps solar energy would be an effective means of pressurizing water, or some other appropriate liquid, to be used in this system of power generation.


    Without more details everything is speculation.


  • Dale Amon

    There is no violation of the 2nd law here. It’s simply another way to convert the potential energy of a water column (or a pressurized equivalent) into electricity.

    If you were doing this in a ‘battery’ you would almost certainly use distilled water. You have to solve the problem of how to
    get rid of it then. You really don’t want lots of water condensing inside your laptop or dripping like the outside of an air conditioner.

    As to gunking up the microchannels, that is more a materials problem than anything else, and you’ve already got the corrosion problem to deal with since you have potential difference across the length of the channel. It had better not be metal in contact with a dissimilar metal. Of course if these are real microchannel plates like are used in image intensifiers (I really have no idea if they mean the same thing or are just using the same words for a different thing) then they are made of glass anyway.

    I think they were talking about an alternative way to get energy out of a waterhead instead of using the usual water turbines like on Hoover Dam.

    Another use is energy storage. Sometimes facilities DO pump water to an upper reservoir during the night so they will have extra surge capacity during the day. This discovery seems ideal for that application.

  • The CyberPoet

    Having just lived through several days without power as a result of Hurricane Frances (but still having had water pressure, as the water supply system hadn’t failed), I can see this as an ideal solution for emergency back-up power… even if it doesn’t deliver more than enough to power a couple lamps or run a car-type (12V, coleman) powered cooler, it would have been a worthwhile addition to our survival kit. I actually stumbled across this link while looking for a water-wheel style generator to take advantage of the power of the tap water for exactly this sort of situation in the future.

    =-= The CyberPoet

  • ahmed

    i will like to know about how to generate an electricity without the use of hydro electric supply

  • ahmed

    i will like to know about how to generate an electricity without hydro electric suppy.

  • ahmed

    i will like to know about how to generate an electricity without hydro electric suppy.

  • Chuck

    Maybe there would be some added benefits when considering the cooling effects of liquids run through tubes. Perhaps overall efficiencies would be better if the liquid ran through channels snuggled next to a smoking hot chip, such as the P4.

    While the liquid takes heat away from the chip, pressure might build up to push the liquid through the microchannels and generate more electricity to power the P4 and make more heat. I am sure it is not a perpetual machine but, if the heat waste could be harnessed as part of the battery system, the efficiencies should be better.