During the full-service summer season, Zealand Falls Hut accommodates up to 250 guests and five crew members each week. Renewable energy systems provide electricity for refrigeration, lighting, the composting toilets’ ventilation fans, and a radio and fire alarm system. The combined electrical demand adds up to about 1.8 KWH per day.
Solar. Four 85-watt PV modules contribute to the total system output. The small array, tilted at 40 degrees and oriented south toward the dramatic Zealand Notch, sits on the roof of a nearby outbuilding. Along with some generator and propane use, the PV and wind systems are the primary power sources in the wintertime, when the microhydro system is off line.
Wind. A Southwest Windpower Air 303 turbine sits about 10 feet above the roof ridge, mounted on a pole bolted to the back of the hut. The hut is located in a small, sloped clearing, and the turbine is squarely in the wind path from all directions except south, where trees tower above the hut. In winter, when loads are reduced and the microhydro system is down, the micro-wind turbine and PV array typically provide ample energy to keep the batteries charged, but occasionally, the staff may need to run the backup generator during cloudy spells.
Hydro. The microhydro system starts in one of Whitewall Brook’s deep pools, a few hundred yards above the hut. An intake pipe brings water into a metal tank fitted with a screen to keep out debris. An intake valve lets staff control the water level in the tank, and shut off flow during storms or maintenance. The homebuilt turbine sits about a quarter-mile below the intake point, in a small shed about 10 yards from the stream. A buried pipe runs from the intake tank parallel to the brook, and down to the turbine. The 100 psi water passes through a nozzle, directing a jet of water at a 6-inch-diameter Pelton wheel. The wheel drives a car alternator, which sends energy to the hut’s battery bank. Once the water has run through the turbine, gravity returns it to the stream.
The microhydro system puts out 300 watts continuously from May until the freezing of the brook forces a shutdown in mid to late fall. With an average output of 7.2 KWH per day, the system provides more than three times as much as the hut needs for its critical loads during peak usage. Excess power is diverted to a heating element that preheats water that’s routed through the hut’s on-demand, propane-fueled water heater.
Hydropower is also harnessed for another crucial need—providing drinking water for the crew and guests. From May to October, the energy of the brook is used to mechanically pump well water into a 500-gallon storage tank. Water is diverted from the main penstock to drive a separate 6-inch-diameter Pelton wheel with two 1/4-inch nozzles with 30 psi of pressure behind them. This “water motor” drives a piston pump, bringing up deep well-water at about 0.5 gallons per minute. For caretakers and crew who have had to hand-pump enough water for a full house of close to 40 people, this apparatus—dubbed the “salad shooter”—is a thing of beauty.
Together, the PV, wind, and microhydro systems charge a 12-volt bank of 10 Trojan L16 lead-acid batteries, with 1,950 amp-hours of storage.