Solar Canals and Quacks are unscientific

That the medical practice in India has been taken over especially in rural India  by Quacks is well known.  Now it seems that other areas of our life, including the governments have been taken over by Quackery.

A week back was this report that in the state of Gujarat a revolutionary new project has been implemented - that of roofing almost 1 km of the Narmada Canal with solar panels to produce electricity.

There is no doubt that much of what is written on the article is true. 

• Stringing up or floating solar panels in such ‘branch’ irrigation canals solves one of the crucial roadblock in solar power generation - the availability of fallow land to install or locate the panels themselves.  We’ve to keep in mind that just like a hydro-reservoir, a huge ‘solar-reservoir’ would also eat or cover up land and locating solar panels over water bodies is one possible solution to the problem.
• Locating solar panels above such water bodies will also increase its efficiency.  One of the headaches in a solar installation is the problem of overheating of panels under intense sunlight conditions.  Solar panels suffer a loss of efficiency, which means less electricity, when they get too hot.  This is apart from the accepted degradation from the usual wear and tear.  The cooling effect of the water flowing and evaporating underneath such ‘floating’ solar panels reduces the overheating of the solar panels and maintains efficiency.

But what stuck in my throat is the claim that such a solar panel installation will prevent evaporation over the 750 metre stretch of the branch canal to the tune of some 100,000 litres of water over the course of an year.

Just read over the article once more.  OT1H, they claim that the effect of water flowing ‘under’ the solar panels will help to keep them cool.  I presume they expect to achieve this cooling effect by the evaporation effect of water, and not by any fancy right-wing mumbo-jumbo.

OTOH, they claim that covering the ‘top’ of the water with solar panels will reduce evaporation, and so save water.  I presume they don’t expect to regain the evaporating water which will cool the panels by some other quack idea - like condensation.
:-P

For what it is worth, here are some background on preventing evaporation losses in water bodies -

• though reduction have been achieved under ideal conditions, reduction in evaporation from free water surfaces has found no practical applications - Fundamentals of Irrigation and On-Farm Water Management, Vol. 1 - M.H. Ali;
• though some regions in India suffer astounding 3,000 mm/day, piped or closed water systems are recommended as the best solutions in this FAO review [http://www.fao.org/DOCREP/003/T0401E/T0401E03.htm]; 
• again though on-bank vegetation screening is suggested as an alternate by this FAO review, there are good reasons for not doing it in this FAQ by Western Australia Dept. of Fisheries on the same subject; (FAQ link at WA Dept. of Fisheries disappeared Oct 2012 and FAO link July 2013)
• OTOH losses due to evaporation in Indian canals are estimated to be as low as 7 mm/day (and not the whopping 3,000 mm/day) - Groundwater Hydrology: Conceptual and Computational Models - K.R. Rushton;
• stemming evaporation losses will not be a selling point as those losses are minimal as per the co-director of Berkeley Water Centre.

Just have a look at the photo - how much is it going to cost to keep that mammoth steel support structure painted and rust free in the ‘evaporative / non-evaporative’ humid micro climate?



My Wicked half whispers, ‘If they don’t keep the water flowing in there, do you know what you will have, with that shade?  The largest mosquito breeding centre in the world!’

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