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Water power

by Jim Heath

Copyright. All rights reserved.
Not to be mirrored on other websites.
First published: Isle of Man Weekly Times.
Published on this website: 2 Jan 2004.


THE WORLD'S biggest water balloon was made by students at the University of California. They piped hundreds of pounds of water into a 30-inch weather balloon. In the end, their creation was waist-high and looked like a giant jellyfish.

The massive object was dropped into the top of a dormitory stairwell. Fifty feet of empty space gave freedom for acceleration. The balloon was going nearly 40mph when it met the ground-floor concrete.

Students in the building put down their books, or woke up.

The plotters later defended themselves by insisting they had arranged a signal to make sure no one was near the target area. They agreed someone could have been killed.

Peaceful uses of water bombs

Such is the power of falling water. Yet it takes a nutty example like this to make the point. Never mind if science declares that the same energy is liberated whether the water falls in a balloon or it falls an equal distance in the buckets of the Laxey Wheel. The effect on the imagination and the practical effects are utterly different. In one case you have a blast of destruction, and in the other case, controlled power. But the energy unleashed is the same.

All that water spilling down Manx rivers is full of energy as well. Normally the energy is wasted making whirlpools and froth. (It takes a lot of work to make water turbulent -- try doing it with a paddle.) But remove the rocks and roughness by letting the water slip down a smooth pipe, or plunge over a drop, and the raw power appears -- sudden and usually welcome, like a jinni.

The greatest gain comes if water is channelled into a pipe. It takes an exercise in visualisation to understand why.

Picture a big pipe (one foot in diameter, say) running hundreds of feet down a steep hill. Imagine the pipe is filled with water, but sealed tight at the bottom with a steel cover. Now mentally cut out a slug of metal from the cover the size of a 10p piece -- and stand aside. A jet of water explodes from the hole and blasts against anything in the way.

If water is poured into the top of the pipe at just the right rate, the pipe stays topped up and the jet at the bottom roars away. And there we are: a weak, harmless flow of water going into a pipe up a hillside, transformed into a torrent of energy down below. The farther the pipe falls, the greater the power.

The power could be increased by enlarging the hole in the steel cover. More water would have to flow into the top of the pipe in order to keep it topped up. When the jet at the bottom was opened to the size of the pipe itself, most of a lazy hillside river might have to be funnelled into the top of the pipe.

How water turbines work

In order to get something useful out of this -- like electricity -- a water turbine is needed. One sort works like a ship's propeller in reverse: the rush of water in the pipe is directed through the blades of the propeller, spinning it. The propeller drives a generator. Up to 80% of the energy in the water can be turned into electric power.

In the other sort of turbine, the jet of water is squirted with full force against only one side of the turbine. Metal cups held out on steel arms rotate into the jet and extract most of its energy.

A water turbine doesn't have to be big. A unit with the same power as the 72-foot Laxey Wheel might be no larger than a dust bin. This compactness makes water turbines disappointing to look at. You can't see anything much, just an inscrutable metal exterior. But if it's working, you can hear a sound -- a combined whine and hum, very penetrating.

No tourists would swarm to see a Manx hydro-electric plant, even a big one. Not enough to see. The pipe would probably be underground and the turbine house would be insignificant, or at most the size of a country cottage. At the top of the pipe would be a reservoir, but in many of the public installations considered for the Island, this would amount to only one or two million gallons. (About the size of the covered-in grassed-over service reservoir at Glencrutchery Road. How many people have noticed it?)

Compare this discretion, technical elegance and low cost with a spectacular but wildly expensive way of getting the power: a series of Laxey Wheels down the hill, one feeding into the other. A Disneyland cascade of this sort would attract tourists from everywhere. Apart from that, the project would be loony.

Personal turbines for unique citizens

So much for theory. If water power has so much going for it, why isn't there more action? That separates into two questions: why aren't individuals putting in small private water-power installations, and why isn't the community pressing for big hydro-electric schemes to benefit the whole Island?

The individuals may have better excuses, so let's look at their side first. To start with, you get an equal number of technical headaches whether you're designing a gigantic water-power scheme or a tiny one. The technical factors are the same. Unless someone has an interest in water power that approaches a mania, the worries and misgivings at the early stages will scare that citizen off. Water flow measurements, types and locations for any dams needed, legal aspects and permissions, the right sort and size of turbine, and a thousand details have to be thought out.

Then there is money. What amounts to a small civil engineering project, plus the cost of the turbine, can amount to £5000 for a modest set-up. Someone with engineering talents and the good fortune to find a used turbine at a reasonable price can cut the costs. But so far only one Islander has done it.

Even a £5000 installation makes sense as an investment -- a long-term one. This is true even if fuel prices stopped rising, because water turbines usually outlast their owners and the machines have spans of time to justify themselves. Yet to part with £5000 now to benefit yourself (and probably your heirs) in a somewhat mathematical way for 60 or 80 years, who might be blamed for wanting to keep the cash?

There are rare things that must come together to bring a private hydro-power plant to reality -- capital, plenty of water, a hilly location, and the will to see it through (a kind of Will to Power). Still, the few who manage it should be envied. Hydro-power is the most delectable of all independent power sources: exceptionally reliable and takes hardly any maintenance; normal AC current of the usual frequency can be produced, so that life can go on just as if the mains current were coming in; and as I've said, the installation will outlast the first owner.

Hydro-electric power for the grid

That's enough about small installations. Let's go back to the question of general interest: why isn't the community considering hydro-power schemes to benefit the whole Island?

It must be said, with a shake of the head, that this is one of the best-studied issues the Island has ever endured. Official monographs go back to 1929. There was another time of manic interest right after World War II. It peaked in a 1948 report by the Isle of Man Hydro-Electric Commission. A report of luminous sanity, if I say so myself. More recently, hydro-electricity projects were recommended in the 1974 Report to Tynwald by the Indigenous Power Sources Committee. More sanity.

Back in 1948 the Isle of Man needed more generating capacity and had the choice of extending the coal-fired equipment or developing hydro-power. The report's hydro-power option was in the Little London area. It would have cost £878,000 and produced 9,400,000 units (kilowatt-hours) of electricity per year. At the time, coal cost £3 per ton (!) and an economic study that projected fuel prices forward at that level concluded there was no economic advantage or disadvantage in hydro-electric schemes compared to coal.

Yet the report also contains a hedged appeal: "The economics of the schemes beyond the 10-year period will depend on the price of fuel and no one can predict what the price will be in 80 or 100 years time, at which time the hydro-electric plant would still, we hope, be generating electricity."

Had they known what we know, their conclusions about the equality of water power and coal would have been different, and expressed -- I might guess -- with force. If the Little London project had been built in 1948, the Island would have had its 9,400,000 units of hydro-electric power every year since. And could look forward to the same amount every year until the middle of the next century.

It's not too late. The 1974 report urges, as a modest step, starting at least one scheme "where a reasonable amount of power could be obtained with limited works." Colby, Glen Mooar, Glen Wyllin, Ballaglass Glen and Laxey are listed.

Raising its gaze to medium-term panoramas, the report says that "at least 10% of the Island's electricity demand could be met from hydro-electric schemes at reasonable cost." So the sites are there, the rainfall is there, the economics are favourable, yet the commitments and decisions aren't there.

It isn't my place in this series of articles to lobby for large-scale projects involving decisions by Tynwald. But I will. Because the conclusion stares at me: a decision should be taken to go ahead with something. There are straightforward economic advantages and the Island would have taken a hop towards independence in energy supplies.

Other hydro-power schemes could gradually be added. In time, some electricity would always crackle on our grid, even if fuel imports were cut off. That's not all: a hydro-electric scheme would be a justified pride to the Island, exactly like the Laxey Wheel was -- and still is.

A few years ago, oil was cheap and was treated like water. It's more than a turn of phrase to say we now treat hillside water "like water." The parallel is accurate, not to say chilling.



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