Thursday, August 03, 2006

progress report

the ground in vermont is finally drying out with the recent heat wave. a couple days ago the ground at destiny steamed as water rose up and into the atmosphere. our excavator is planning to start work on the septic system this coming monday and will also be working on landscaping garden terraces and reworking the circle so that it drains. he'll begin some site grading around the kitchen area, installing a swale above the construction site to help dry it out for the installation of a foundation once we get our building permits.

we are still working on getting our water system finalized. it has been a challenge because our water requirements as a campground are difficult to meet without spending a lot of money. we're trying to avoid that. the simplest system, a 230-volt pump in the well feeding a pressure tank, requires a pump that draws about 5500 watts of power on startup. while this is easy for the grid to handle, it's a chore for a small alternative system and a waste because the system has to be sized to accomodate the start up of the motor, which after it has started draws just 1/3 of its startup wattage. so, your system has to be two to three times the size it needs to be because of your well pump. there are controllers that slow start motors, which would help, but a better solution is to avoid using AC power at all and use the kind of power that solar panels produce directly: DC, or direct current.

i attended a workshop on solar water pumping at solarfest a couple weeks ago and learned a lot about low-power DC pumps that are being installed in remote locations worldwide. unfortunately, these pumps do not produce the flow that the AC pumps produce, partly because they use less power. but, depending on the static level of our well (the level of water in the well casing) we may be able to utlize one or two of the DC pumps in combination with a storage tank in the kitchen building to provide our water supply. even though the pumps are low power, they still use enough juice that installing solar panels to power them would be expensive. the word at solarfest was that new technologies will increase the efficiency of solar panels over the next few years. my current thought is to set up destiny with low-powered DC pumps that run off batteries charged periodically by a generator and perhaps a single solar panel. as we move on and have funds to grow, we can install solar panels to augment and eventually eliminate the generator.

we also explored the idea of pumping water uphill to a large storage tank that would gravity feed the camp. for you budding engineers out there, 2.31 feet of rise produces 1 pound per square inch (psi) of water pressure. our camp must have at least 40 psi in its lines so you do the math and the tank has to be 92.4 feet above the highest fixture. my rough estimate is that this means the tank would be about 500 feet on the ground uphill from the bathhouse. since there has to be a feed line and a return line, that's over 1000 feet of water line that has to be installed. the beauty of this system is that once the water is uphill in the tank, there's no pumping required. whether there is a site that could host a 2000 gallon tank uphill is unknown. clearly, this system would only work in warm weather and the water lines risk being damaged by falling trees and animals if they are not buried.

so, that's where we are with water and power. i sure have learned a lot about solar and water in the process. this coming saturday, at 10am or thereabouts, we'll be having a circle to discuss all this at destiny.


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