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Wednesday, 14 November 2012

A reverse ion drive as a hydroelectrical generator

Bujagali Falls, Jinja, Uganda in 2003
prior to the dam. credit: J. Firth
Nine years ago to the month I sat on a bank of the Nile in Jinja, Uganda, discussing the then proposed Bujagali Falls hydro project with an international development expert.

Hydroelectric power is attractive, especially in developing countries.

But hydroelectric power comes with a reasonably high price tag and high ecological impact both at the dam site and downstream - which, with a very long river like the Nile, is a substantial area.

I began to plot ways of capturing energy from the flowing river without such large capital outlay whilst minimising the environmental impact.

I was especially keen on micro generation at the time as that would come with the added advantage of not requiring lengthy power transmission cables.

I had the idea for a kind of reverse ion drive, where the water in the river is ionised before passing through a strong magnetic field to create an electric current due to the motion/thrust in the river's downhill flow.

I'm not sure if this has been tried before and I have, for many years, intended to test out the theory with a practical experiment.

A reverse ion drive as a hydroelectrical generator

Since I have failed in nine years to build a scale model of a fast-flowing river and I doubt I'll get time in the next 9 years I thought I'd kick the idea out there to see what comes back.  If there's any research in this area I'd be interested to read it.

The advantage of such an approach over conventional hydro power is it should be cheap to build relatively small generators for use in developing countries.  With no moving parts it should also be easy to maintain, but   I have no idea at this stage if the approach will work and, if so, what power it would supply for any given volume of water passing through.



  1. that is a magneto hydrodynamic generator http://en.wikipedia.org/wiki/MHD_generator I think it won't create much power (extracting power from a river means you slow it down so it backs up slightly and pushes harder against your apparatus this doesn't feel like it would generate much pushback against the water) might just be enough to be useful in some context though.

  2. plus I have no idea what the ecological effects downstream might be of a plume of ionised water coming down

    1. Brilliant - thanks for that, I had been Googling around but never arrived at MHD.

      As for the ecology, the Wiki page states experimental MHD propulsors have been developed (? or conceived at least) for ships - and in Hunt for Red October for submarine?!) so I guess the impact would be equivalent.

      One would thing the ions would recombine quite early so not leave much of the river alkaline/acidic.


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