The good news about hydro is that you do not need a large battery bank like wind and PV systems. We install for most of our clients a battery bank of 8 x T105's at a cost of $2000 NZ (1400 US). Many clients scrounge ex Telecom batteries for a crate of beer. We use an ex Telecom set ourselves that we were given and 10 years on we are still using them. There are still in very good order.
With hydro you do not cycle your batteries much, this ensures they have a very long life. The batteries we are using at the moment are 23 years old and still going strong. I would recommend a small Pelton turbine, on 15m head and 3 L/s you would generate over 200 Watts. With 5 kWhr per day at your disposal you will be able to chainsaw away for some time. All you will need is a large inverter and C40 regulator and you are in business. The flexibility that being able to plug in normal power tools gives is much greater than compressed air. If you need compressed air just run a compressor off your inverter - we do in our workshop. So long as you have a 3-3.5 kW inverter with a good surge ability starting a 2.5 HP compressor is not problem. Alternatively you can buy a smaller inverter and run a small compressor with a large storage tank. We run a lathe, compressor, welder, thicknesser, buzzer, dishwasher and clothes dryer all off a 3.0 kW inverter that has a 7 kW surge ability. We only generate about 300 Watts most of the time. Regards Michael Lawley Renewable Energy Engineer EcoInnovation 671 Kent Road R.D.1 New Plymouth New Zealand Phone: (NZ) 06 752 2765 Web site: www.ecoinn.co.nz email: [EMAIL PROTECTED] . ----- Original Message ----- From: Forrest Robinson To: [EMAIL PROTECTED] Sent: Wednesday, November 03, 2004 5:38 AM Subject: [microhydro] Storing energy as compressed air I have a unique piece of land that has a 100 year old cistern on top of a waterfall. At some point I will re-establish the pipe and use the ~50' of head for power generation via a pelton wheel at the bottom. I am in no rush for power in the form of electricity since there is no dwelling on the property and I cann't justify replacing batteries every couple years. However, we often camp on land and do heavy crafts (chain saw rustic furniture etc). It occurs to me that I can put a flow over wheel adjacent to the cistern and use it to drive an air compressor. I can bury some tanks in the ground for compressed air storage. From a control standpoint I suspect the wheel would stall once the stored pressure reaches a limit or I can put an pressure relief valve that dumps air into the water once it gets up to ~120psi. The fish wouldn't mind additional airation of the water! The compressed air would drive all sorts of air tools. It would probably be quite slow to recover a depleted tank, but that doesn't matter. I can always add tanks, or go fishing. I'm thinking I can find an old-fashioned (oil type) compressor that normally would have a 1-3 hp electric motor for a drive. My flow over water wheel will be about 5' diameter with ~50 gpm flow so the hp I can deliver to the compressor will be a small fraction of what the compressor is capable of, however I will run it slower but with the same torque. The torque seems to be just a matter of pully diameters. I question if air compressors are in-efficient if run slowly. If you have experience with this I'd love to get some feedback. Forrest Robinson Does your company feature in the microhydro business directory at http://microhydropower.net/directory ? If not, please register free of charge and be exposed to the microhydro community world wide! NOTE: The advertisements in this email are added by Yahoogroups who provides us with free email group services. The microhydro-group does not endorse products or support the advertisements in any way. More information on micro hydropower at http://microhydropower.net To unsubscribe: send empty message to [EMAIL PROTECTED] Yahoo! Groups Sponsor Get unlimited calls to U.S./Canada ------------------------------------------------------------------------------ Yahoo! Groups Links a.. To visit your group on the web, go to: http://groups.yahoo.com/group/microhydro/ b.. To unsubscribe from this group, send an email to: [EMAIL PROTECTED] c.. Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. 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