Date of Award

6-6-2014

Document Type

Thesis

Publisher

Santa Clara: Santa Clara University, 2014.

Department

Electrical Engineering

First Advisor

Shoba Krishnan

Abstract

In alignment with Santa Clara University's sustainability ideology, the outdoor science school WaldenWest desired to further its students' education through a greenhouse with working electricity. Following greenhouse purchase and assembly, underground wiring for AC, DC and Ethernet lines were sized and installed. A substation was then designed and built in a designated shed, integrating wind turbines and photovoltaics rom past capstone projects. New charge controllers, batteries and circuit breakers were urchased and configured for the system. Worst-case electrical load and solar shading analyses also revealed that these older energy sources were collectively inadequate, so a secondary solar array was designed and flush-mounted to the shed roof; the system falls lightly short of desired year-round performance, but is otherwise a drastic improvement. Electrical measurements show that power is received at the greenhouse with a less than 3% voltage drop, meeting national Electric Code standards. To maintain the greenhouse environment, substation loads are specifically selected to allow for temperature control. These are driven by the Supervisory Control And Data Acquisition (SCADA) system, which never leaves the greenhouse; an enclosed Raspberry Pi automates load operation through SainSmart relays and simple comparative logic. To account for both varying seasonal weather conditions and client accessibility, a Graphical User Interface (GUI) is programmed to allow adjustment of all relevant control parameters via Wi-Fi in real-time. A battery monitor from a past capstone project is also reconfigured to run on Linux to estimate remaining stored energy. Project analyses include ethical, aesthetics, commercial benefit and basic photovoltaic rate-of-return analyses. Hypothetical scenarios are frequently presented to investigate the potential consequences of client and residentially-replicated usage of the entire system. It is also estimated that the combined photovoltaics will result in a lifetime net zero energy in 4.3 years of continuous expected use. Future project work involves tasks that could not be accomplished within the project time frame and budget. Among these include a larger solar array; the 24VDC integration of the horizontal wind turbine; rigorous seasonally-based testing of temperature controlling mechanisms for better parameter adjustments; and finally, the propagation of electrical power beyond the immediate premises and into the entire Walden West garden. Based on client needs, inspiration for future project work will likely draw from the tremendous success of the Milwaukee, Wisconsin non-profit organization, Growing Power.

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