Increasing reliable produce farming and clean energy generation in the southwestern United States will be important for increasing the food supply for a growing population and reducing reliance on fossil fuels to generate energy. Combining greenhouses with photovoltaic (PV) films can allow both food and electric power to be produced simultaneously. This study tests if the combination of semi-transparent PV films and a transmission control layer can generate energy and spectrally control the transmission of light into a greenhouse. Testing the layer combinations in a variety of real-world conditions, it was shown that light can be spectrally controlled in a greenhouse. The transmission was overall able to be controlled by an average of 11.8% across the spectrum of sunlight, with each semi-transparent PV film able to spectrally select transmission of light in both the visible and near-infrared light wavelength. The combination of layers was also able to generate energy at an average efficiency of 8.71% across all panels and testing conditions. The most efficient PV film was the blue dyed, at 9.12%. This study also suggests additional improvements for this project, including the removal of the red PV film due to inefficiencies in spectral selection and additional tests with new materials to optimize plant growth and energy generation in a variety of light conditions.

This research paper explores how different relationships between people and nature can be fostered by learning experiences to bridge harmful gaps in the field of sustainability. Current disconnectedness from nature and people both within and across geographical borders hinder the cultivation of sustainable solutions. After attending a sustainability-oriented educational experience abroad in Ecuador recently, I decided to investigate how cross-cultural exchanges in Ecuador influences participants’ views of nature, new points of intersectionality participants learn while amongst nature in Ecuador, and what about this experience made it uniquely meaningful. Research methods included individual interviews and a group hike and picnic focus group discussion to collect qualitative data. I found that during this experience, students were able to lean into being vulnerable with each other, connect with indigenous community members beyond language borders, and connect with nature in ways that fostered awareness of the human position within it. From this, I learned that there were unique aspects of this learning experience that allowed for these relationships to be built and therefore for sustainable knowledge from the trip to stick when participants got back to the United States. The amount and flexibility of learning and processing time and dynamics created by classroom structure were important variables to the effectiveness of the learning experience. Institutions can learn from these experiences and connect people back to nature to implement successful sustainability solutions in the future.

Wastewater treatment plants (WWTP) are facilities with a large potential for energy savings and improvements, but the factors behind their efficiency remain largely unstudied. In this thesis, a limited study toward developing a benchmarking tool to allow comparison of operation of WWTPs in terms of energy intensity (EI) will be analyzed. While the comparison of WWTPs is very complex, an initial start with comparing EI will be a useful tool. The methodology for this will first involve a literature review into EI at WWTPs to understand current statistics. After this, publicly available data gathered by Department of Energy sponsored Industrial Assessment Centers (IAC) from 2009 to 2021 of WWTP EI will be studied to show the potential for improvement of EI. This comparison can highlight certain states that currently exhibit more efficient plants, change in efficiency over time, as well as compare specific treatment technologies in literature to the general data gathered from the IAC. Lastly, the first step toward development of this benchmarking tool is a study of the 13 WWTP operations analyzed by the Arizona State University (ASU) IAC using a data envelopment analysis (DEA). This DEA can begin to show how a tool could be used with more data to accurately compare and benchmark a WWTP based on performances of similar WWTPs. This tool could allow operators a possibility of seeing how well their performance compares, and work toward an improvement in their EI.

Water heaters that are manufactured for swimming pools come in several forms, most of which require an electrical input for a source of power. Passive-circulation systems, however, require no electrical power input because fluid circulation occurs as a result of thermal gradients. In solar-based systems, thermal gradients are developed by energy collected from sunlight. The combination of solar collection and passive circulation yields a system in which fluids, particularly water, are heated and circulated without need of assistance from external mechanical or electrical sources. The design of such a system was adapted from that of forced-circulation solar collector systems, as were the equations describing its thermodynamic properties. The design was developed based on such constraints as material corrosion resistance, overall system cost, and location-controlled size limitations. The thermodynamic description of the designed system was adjusted on the basis of the designed system’s physical aspects, such as the configuration and material of each component within the solar collector. Numerical analysis performed with the altered thermodynamic equations projected a total energy gain of 7.39 W between 9:00 and 10:00 A.M. and a total energy gain of 13.12 W between 4:00 and 5:00 P.M. The temperature of heated water exiting the collector system was projected to be 17.62°C in the morning and 25.56°C in the afternoon. The morning projection utilized an initial fluid temperature of 12°C and an ambient air temperature of 13°C, while the afternoon projection utilized an initial fluid temperature of 17°C and an ambient air temperature of 22°C. Field testing of the designed passive thermosyphon solar collector system was performed over a period of about one month with one temperature measurement taken at the collector outlet in the morning and another taken in the afternoon. For an ambient air temperature of 13°C, the linear regression developed from the morning dataset yielded an outlet water temperature of 20°C and that for the afternoon dataset yielded an outlet water temperature of 39°C for an ambient air temperature of 17°C. The percentage error between the projected and measured results was 13.51% for the morning period and 52.58% for the afternoon period. Numerical simulation and field data demonstrated that while the collector system operated successfully, its effects were limited to the volume of water immediately surrounding the outlet of the system; the rate of circulation within the system was too low for there to be a meaningful increase in the temperature of the water body at large. The stated results demonstrate that while the particular configuration of passive circulation solar collection technology developed in this instance is capable of transferring solar thermal energy to water without additional energy sources, significant modifications are necessary in order to improve the effectiveness of the technology. Such changes may come from improvements in material availability or alterations to the configuration of components of the collector system.