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Amanda Potter & Chris Greacen

In 1978 the building was not remarkably different than thousands of American houses. Like most houses, it wasn't energy efficient — gas and electricity were cheap. It dumped its waste directly into the city's sewer system. The food that its occupants ate was purchased from distant markets. Perhaps the only thing that distinguished this house on 16th Street and Cluster Lane in Arcata, California, was its scheduled demolition as part of an expansion of Humboldt State University (HSU).

The history of this building's miraculous transformation is beyond this article, but the results are clear. The house is now CCAT, the HSU Campus Center for Appropriate Technology. CCAT is a thriving student-run demonstration center for appropriate technology and self-sufficient urban living. Reliance on outside resources is minimized. Most of the electricity, home heating, and food consumed at CCAT are produced using the sun, wind, and rain that fall on the small city lot. Nutrients such as kitchen and bathroom wastes are recycled to be reused by the house's gardens.

This transformation has been the work of students and community volunteers. HSU's appropriate technology engineering curriculum includes student projects such as CCAT. Three student co-directors live full time at CCAT, and oversee projects, give tours, and run the day-to-day business of managing the demonstration house. They are appointed by a steering committee of faculty, community members, and past directors. This year CCAT received enough funding to hire a few more people to manage the increasing flow of activity. Lots of other folks come in, leading and participating in weekly workshops on everything from beer brewing to hydrogen energy to organic gardening. Last year over 1,200 people toured CCAT, and nearly 800 participated in workshops.

Others come to use CCAT's library. Their well-organized collection of books, magazines, and newsletters on gardening, renewable energy, and appropriate technology make our files here at Home Power look ill. This information is often difficult to track down, and it is good to see it organized in one place. There should be a library like this in every town. Material can be borrowed by anyone in the community, or you can recline on the couch and browse at will. The library is also a self-guided tour which you can take any time the place is open.

Pullin' the Plug

In spring of '91, CCAT asked Pacific Gas and Electric (PG&E) to disconnect the power lines. Most of the home's electricity now comes from 22 photovoltaic (PV) panels mounted on CCAT's roof. All the panels were made by Solec, and were part of a test facility at Jet Propulsion Laboratories (JPL). The panels put out 30 Amperes at 15 Volts on a sunny day. A Sencebaugh wind turbine on a 40 foot tower supplements the PVs on windy days. During wind gusts it has supplied as much as 25 Amperes. Unfortunately it requires 15 mph winds to start generating power, which, at only 40 feet up, it doesn't often receive.

Arcata is on the coast of far northern California. For weeks on end, especially in winter, the town is fogged in. In the renewable energy world, these are "low energy days." For these times, CCAT uses a three horsepower Honda engine, modified to run on natural gas, which drives an 80 Ampere automotive alternator. This 12 Volt DC engine generator uses a student-made Mark VI electronic field controller to control output current. Former co-director Mike Nelson was careful to explain that CCAT has disconnected from the "E" of PG&E, but utility natural gas is still used for back-up electricity generation, and for cooking and some water heating. Fortunately, natural gas is the cleanest burning of fossil fuels.

Batteries Included

Electricity is stored in six 350 Ampere-hour Trojan L-16 lead-acid batteries. To prevent overcharging, a 50 Ampere Enermaxer voltage regulator shunts any excess current to an air heating element. The PV, wind turbine, and shunt regulator circuits are protected with 50 Ampere Square-D circuit breakers. The engine generator circuit gets a 60 Ampere breaker. DC loads to the house are protected with a 50 Ampere breaker. All the electricity flowing into or out of the batteries must pass thorough two 500 Ampere 50 mV shunts. A Cruising Equipment Amp-Hour+, and a SCI Mark III monitor use the voltage drop across the shunts to keep track of the current flowing in and out of the battery. A Trace 2012 inverter, protected with a 500 Ampere ANL fuse, powers ac loads. The inverter feeds directly into the ac circuit breaker box which formerly received PG&E power.

Where the Energy Goes

CCAT's electrical system provides power for household needs of three resident co-directors and people who come in and out, power for office equipment during business hours, and power for weekly workshops (power tools). Power use is detailed in the chart below. The house is wired for both ac and DC. Efficient compact fluorescent lights provide the bulk of lighting, supplemented by 60 Watt DC halogens. Regular ac incandescents are used for intermittent lighting such as closets. The refrigerator is a sixteen cubic foot 12 Volt DC Sun Frost, one of the first ever built. It uses 200 kilowatt hours per year on average, compared to the 1300 kilowatt-hours per year for a typical refrigerator of the same capacity. Sun Frosts are made in a small factory in Arcata, and Larry Schlussler, the founder of the company, donated this unit to CCAT.

CCAT's Big Power Consumers


120 vac appliance




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