On Fri, 17 Jun 2005 18:02:44 GMT, "Pete C."
wrote:

See my notes below saving four steps of energy conversion for
applications where you are able to use air power directly such as nail
guns and die grinders. Four fewer conversion steps *has* to be more
efficient.

You only need to calculate the numbers for volume and consumption, as
I'm in agreement that with good wind, it's feasible that a resourceful
scrounger could put up sufficient rotor area.

It is far cheaper and lower maintenance to use a
large air or water reservoir than to use a huge string of batteries with
limited life spans and hazardous lead and acid to dispose of properly at
every battery replacement.

Excellent point, and I've committed it to memory in case I decide to
do a utility-scale installation. :-)

The batteries in your string may last what, perhaps 8 years?

They're nearly ten years old now, and I won't be surprised if they
make 15 or 20. But home power systems pretty well always need *some*
batteries, so all we're talking about is whether the size could be
reduced somewhat by an additional system. And keep in mind that a
primary goal of home power (at least at my place), is to minimize the
energy that makes a trip through the batteries.

Perhaps because I haven't seen the concept even proposed in any
alternate energy books. As far as I know CAS and PH are both fairly new
concepts that originated from electric utilities need for a way to store
excess generating capacity during off peak times for use in peak shaving
later.

Well, since my uh, somewhat unconventional neighbor ;-) thought of
doing compressed air, I think that if it were viable for home power,
it should have become popular by now. The subject of home power scale
pumped hydro comes up here regularly, and those impossible numbers can
be found in the archives.

This would primarily apply to wind generation where peak gusts could
produce power faster than the batteries could accept it, causing that
power to be dissipated by the charge controller.

I've never heard of that being an issue, and it certainly hasn't come
up at my place, which has a high ratio of wind charging capacity to
battery size, and some pretty gusty winds.

Any reason not to combine both and put up your tall tower with the
electric gen up top and hang a compressor at a lower point on the same
tower?

I think that once you run some numbers, you'll find that an air system
with the capacity you're thinking of will need several big rotors.
While I do have a small wind turbine scabbed onto my tower some
distance from the top, I couldn't add even one Bowjon type thing the
same way. Cheap rotors (multi-piece sheet metal) end up being pretty
heavy. IIRC, the Bowjon has a gearbox as well as the pump.

Guess you just need to setup a heat exchanger from your inverter(s) to
capture the waste heat for your DHW.

If you're serious, I'd like to see some numbers. How much can the
waste heat from 12kWhrs of inverter use raise the temperature of 80
gallons of water? And how practical is it to capture that by adding
yet another element to a solar water-heating system?

Soft start inverter drive to a three phase well pump with an unloader
valve?

Except for the unloader valve which isn't required, that's an approach
I've recommended previously here, partly because the drop in wire size
can save a few bucks on a deep hole. But you're still talking about a
good-sized inverter, plus a transformer, plus a VFD. Considering the
other benefits of dual inverters, our preference was to do that
instead, even though at 1/2hp a VFD wasn't required here, so the
savings on that didn't count.

The only way to get reasonable efficiency out of a gen/bat/inv setup is
to size the generator to just barely above the average load and run it
24x7, and that requires a pretty specialized generator to handle that
duty. Not something I'd consider unless I had my own nat gas well, or
bio-gas generator.

Why do you say 24-7? An affordable startup concept I've recommended to
a few is an inverter/charger, batteries, and a Honda EU series. Run
the generator, say, every day for a couple of hours at max output
during peak load times, and for several hours every so often for
battery health. Add solar, wind, etc. as budget allows until generator
time is minimal. For example - DR1512, EU2000, and a string of
batteries from Sam's Club - perhaps $2k total.

Looks like you had to go to some extremes to get your Internet
connectivity.

We were fortunate to be the telco's guinea pig for a couple of radio
systems. The current one gives us multiple POTS lines (although we
only use one) plus DSL. Standard bill, same as if we were hard-wired.
Satellite intenet and next gen wi-fi brings similar connectivity to
just about anyone who needs it.

Perhaps as I'm able to build up some AE projects I'll be able to cut
operating expenses enough to start to get ahead.

You have a home shop and an idea for a cheaper alternative to
batteries, the cost of which home power users love to complain about.
Do I need to spell it out for you? ;-)

Wayne