But I think it might be a mistake to link to Tim Hunkin's site... it's like calling a subroutine that never returns! I just spent (another) few hours over there, before realising that I hadn't finished reading what you'd written. Did you also see this piece about playing with technology?

http://www.timhunkin.com/a118_technology_is_human.htm

Perhaps you should only link to Tim's site at the ends of your posts? Like I didn't.

Using their minumum of 20cm head, then we actually need a water flow of .73 cubic meteres per second. 730 literes per second. IF I am reading the flow on the Don river in Melbourne it is actually higher then it's low flow!

Even if we assume as you did a 60 centimeter head you still need a pretty good flow. Around 240 literes per second using a 70% efficiency.

Definately a great investment... Provided you happen to own the niagra falls.

The biggest problem with installing a shore-based solar array given current solar technology, is that, short of a 100% reliability rating on the panels, they'll never make it worth the money or trouble....

Just be glad its a private business, not the US Government isn't installing solar panels on the Pentagon... Somehow it would be a 1.2 BILLION dollar installation, and still only have 170kW peak rating, and.... you get the idea.

BTW - it's winter here and even on the rainiest day we've seen yet (very rainy) the system was producing 60kW. So the system itself is wonderful... the implementation of it stinks though.

Of course, that ain't happening yet. What with plasma TVs and more and more air conditioners around the world, per-home electricity budgets are still rising. It's not all going one way, of course - efficient lighting's becoming quite normal, and there's a promising movement towards eliminating "vampire" devices that suck juice while "off".

Home alternative power solutions also don't have to have a battery bank. If you've got a grid connection as well, your solar/wind/whatever can supplement that and, in more enlightened countries, allow you to run the meter backwards if you're making more than you need.

I live aboard a sailboat(in the USA), and happen to own a Southwest Windpower Air-X Marine wind turbine (http://www.etaengineering.com/windpower/air-x_marine.shtml Ask for it by name - they are the best! ), and I am very happy with it.

In Watts / $, it fails miserably compared to my Coleman 1500W Generator( which cost me $300 on sale, and sips gasoline at about $3/Gal if you don't shop around, $2.25 at the moment if you do).

However, the advantage of wind power(and, for that manner, solar panels as well) in maritime applicatios is that they do not require gasoline, diesel, or even for the boat to be moving. This is VERY handy when you happen to be sailing across an ocean, or anchored out in the arse end of nowhere(say, the less populated islands in the South Pacific), where there simply isn't a supply of fuel.

The reason that wind generators work extremely well for sane boaters(sailboats) is that we have a very low energy budget. I use perhaps 50A @ 12V DC (600W) in the course of a day. This is 0.6kWh. The biggest consumer I have at the moment is this damned laptop, with a 60W power supply, and my 13" TV. This is a rather sizable downgrade from the consumption when I lived ashore, where the EIGHT computers I had in my bedroom(I was 17 at the time. I won't go into the amount in the "server room" in the basement) blew my 10A breaker if I turned on too many lights(In the US. the lights are normally on the same circuit as the wall outlets. Less wiring, I suppose)

Sooo.... If you happen to have a nice, low, power budget, wind, water, or solar power will work very nicely with a small installation. You'll need batteries, and an inverter if you HAVE to have 120/240V AC service, but 12/24V DC works well enough.

If I need more power, I have that 1500W generator, after all.

If you want to use SI units, the correct equation is:

Power output in Watts = Head in m * Flow rate in m^3/s * efficiency as a fraction of 1 * g in m/s^2 * density in kg/m^3.