So in the CleanTech news there is a picture of the small test unit that they are playing with:

Quoting Ash:
15 amps at 24 Volt went in, i was BLINDED by 1Kw of lights out. This thing could build up 20Kw with the fly wheel. I saw a cable that has a 600 kilo tolerance broken like a twig, this thing is POWERFUL.
Let's do some crunching:
"The mechanical horsepower, also known as imperial horsepower, of exactly 550 foot-pounds per second is approximately equivalent to 745.7 watts."
So (1000/745) * 550 = 738 foot-pounds per second to give you 1000 watts of mechanical power.
Now let's be generous and say that the efficiency of the mechanical to electrical conversion is 80%.
Therefore you need (1/0.8 ) * 738 = 922 foot-pounds per second of mechanical energy per second to get 1000 watts of electrical power.
Also let's assume the column of water is 18 feet high and the buoy moves up for six seconds and then moves down for six seconds.
You need a really big buoyancy force pushing the buoy up in the column of water. Water is 62.4 pounds per cubic foot.
The buoy would have to be (922/62.4) = 14.7 cubic feet in displacement if it was rising at the rate of one foot per second. Since we are assuming a 50% duty cycle, the buoy would have to be 29 cubic feet in displacement if it was rising at the rate of one foot per second.
With a height of 18 feet and a travel time of six seconds, in reality for this example the buoy wold be traveling at a rate of three feet per second.
So the buoy would have to be (29/3) = about 10 cubic feet in volume to sustain a 1000 watt electrical output.
Let me try to work that backwards now:
10 cubic feet x 62.4 pounds per cubic foot = 624 pounds.
624 pounds x 18 feet = 11232 foot-pounds.
11232 foot-pounds in 12 seconds = 936 foot-pounds per second.
That checks out with my initial estimate of 922 foot-pounds per second since there are rounding errors introduced.
When I look at the picture, you see what might be a "buoy" at the top of the red and white striped "barber pole." It looks like it could be about 10 cubic feet in volume so that appears to check out.
However, we can't forget that even though the size of the "buoy" appears to check out assuming an 18-foot buoy displacement and a six seconds traveling up and six seconds traveling down the column of water,
the whole thing is sill being powered by about 1250 watts of mechanical compressed air power and that doesn't just appear like magic out of nowhere.As a reminder, these are all just estimates that I am making here. There is
real value in doing this and it's a worthwhile exercise for just about any kind of claim that you might encounter.
MileHigh