Wednesday, 28 January 2009

Email to European Small Hydro Association

Sick of writing so much in emails, then having to rewrite it all again into bloggage, so what the hell - i'm pasting it as it is. This more or less summarises what I'm doing right now.

As I explained today on the phone, I am undertaking a research on the potential for old water mills to be transformed as micro hydro generators. My focus area is the municipality of Monção, in the far North of Portugal, in the river Minho basin. This is a small county of around 200km2, with two main rivers feeding into the Minho, and many smaller streams feeding these two tributaries. Average annual precipitation is around 1250mm.

I have spent a few days going through a regional Kadastra of old mills, and found that there were, in the 1940s, over 650 water mills in this county alone. At present, almost none of them are functioning and not one produces electricity. Most are in a state of disrepair or ruin. But many of them are still intact, at least the open water channels (levadas) are still there, parts of some of the weirs, the mill buildings themselves and so on.

I am trying to find out what kind of turbine would fit within these old mill settings. Most have low head (1 to 3 m) and flow is limited by the size of the channels (I have estimated flow at between 110 l/s and 200 l/s).

As I'm sure you are aware, European (and national) river acts and regulations mean that concession to extract water or do any construction along rivers is... complicated, but not impossible. I have met with the regional authorities in this regard and they stated clearly that they are quite keen to support the rehabilitation of old mills, as long as it adheres to the strict ecological / environmental guidelines.

With regard to hydro electric turbines I have found it rather difficult to find a system that could work with this low head/flow. And most companies I have contacted are not interested (it's too small they all say). I am not deterred by their lack of interest. I feel certain that there must be a technology that can bring these engines of former rural enterprise back to life.

For example, I have read about the Nepalese "ghatta" wheel - which is remarkably similar to the horizontal wheels in this area. Due to lack of rural electrification in Nepal, the ghattas have continued to function, and for some years now a local intermediate technology group and various external actors have helped develop an "improved water mill" (IWM). This now provides a little power, as well as the grinding or milling services they also need. It is, by all accounts, a "multi functional" system. Could these IWMs could be tranferred, or adapted, to the local setting here?

Perhaps the nascent hydrodynamic screw made by Ritz-Atro could work in some of the mills - given it's ability to allow migratory fish to pass through it unharmed. This is a major issue in some smaller rivers here.

And there are low head Francis systems I have read about, but I am worried that this would require major civil works around the site for new pipe channels, etc. which could affect the aesthetics of the area, etc. Also, they may be too expensive.

I have studied the Portuguese renewable energy tariff, and in terms of hydro it could be attractive for small systems (under 4kw).

So these are the issues. Would you be able to help?

As I mentioned to Lauha Fried today, I believe that there is enormous potential for EU / regional funding for a more profound study and pilot projects in this area. Indeed, it is the wider area - in 10 days I am meeting a group from Vigo university (Spain, Galicia) to view a mill project they have. And they too have asked about power generation potential). (Galicia is also full of these old mills).
I have met with a professor from Portugal's largest civil engineering faculty, FEUP ( and he has indicated that his department of hydraulics would be keen to get involved.
I can also be certain that local municipalities and related NGOs would be interested.

Thus we have all the makings of an interesting funding proposal for a serious piece of study to breath life back into the moribund mills of this region.

It would be great if ESHA would be interested to participate.



Wendy said...


This is a great idea. Keep us posted! I'm looking at microhydro generation on my own site in the Beira Central/Beira Alta region, though I have the opposite situation to you -- high head and low flow. Have you looked at Navitron's range of turbines? ( They would likely have just the unit for your situation.

BTW there are many old mills here too, and some are already in the process of being restored and used to generate hydro power, but in a piecemeal independent way. I really like your initiative to galvanise support for this on a regional/EU basis.

Moona said...

Hi Wendy. Thanks for this feedback (wow, great to get feedback. I thought i would just be posting into the ether for the practice of just scribbling down my thoughts)
Not sure if you even get this message. Don't know how to reply properly yet, or set up links and all the other cool blog stuff.

Re Navitron, great company I agree (so much cheaper and not much worse eqiupment, but definately less hardy). The low head systems would unlikely be able to handle the flash flooding events.

Actually I am interested in adapting the Nepalese Ghatta wheel (very similar to the horizontal mountain mills here). They have created higher efficiency "multi purpose mills" that generate some power but also allow for grinding, oil expelling and other handy services. I like this idea and will try to get one built locally and will compare the costs.

I will post more on this subject soon since there is a bit of interest out there. Check out my post from January called "echoes of old watermills" for a bit of background...


Wendy said...

Interesting what you say about Navitron and hardiness. Thanks. I'll be bearing that in mind, though suspect hardiness is not something present technology does too well wherever you source your turbines. I like the idea of the Nepalese Ghatta wheel adaptation. The old ways are often the best.

PS. Are you related to Angus W-M?

Quinta das Abelhas said...

hi magnus
you have another comment over at
could you send me your email address please as i've lost everything when my email software crashed horribly on me.
cheers, sophie

chris said...

Good luck, We have restored an have an old mill in Central Portugal (nr Fig D Vinhos) and are generating all our own power as we are well off the grid.
We are using a 500w powerpal ( turbine from 1.6m head and trying to get a mains connection in to sell back excess (would install an addition 1kw or twin 500w) but this proving very costly.
You are right, there are lots of mills ripe for this sort of rejuvination, my thoughts are without the full scale support of the electricity company it is a steep uphill struggle. We need to put pressure on them to get involved, increase the buyback to 3 yrs would be a good starting point.

Chris Geake

Magnus said...

Very pleased to hear about your experience with powerpal. Would love to talk to you about this, and how the system has worked, how you dealt with Aguas and the environmental permissions, etc. Could you possibly write to me at:
and we can chat.
I have been in touch with they guy who set up powerpal, and another Canadian company called Energy Systems and Design, that do similar products.
Look forward to hearing more.