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Solar Power and Controllable Light Transmission for Greenhouses

Description

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.

ContributorsGunderson, Evan (Author) / Phelan, Patrick (Thesis director) / Villalobos, Rene (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)

Created2021-05

Evaluating the Potential of Greenhouse Agriculture in Phoenix

Description

This thesis conducted an evaluation of the performance and return on investment of a 2 x 6m, simple design greenhouse, as a climate control technology. Specifically, differences in internal microclimate conditions between a greenhouse treatment plot, and sun and shaded control plots were assessed and related to observed differences in crop yields across these plots. Growing conditions and productivity of two crops, tomato and swiss chard, which were grown over summer and winter growing seasons, respectively, were compared. It was found that the greenhouse was associated with improved growth conditions (as measured by the R-Index) for both crops but resulted in higher productivity only for tomatoes. Return on investment and food security impacts from the scaling of greenhouse agriculture were also explored.

ContributorsKline, Jarod Neale (Author) / Aggarwal, Rimjhim (Thesis director) / Agusdinata, Datu Buyung (Committee member) / Vanos, Jennifer K. (Committee member) / School of Sustainability (Contributor) / Economics Program in CLAS (Contributor) / Barrett, The Honors College (Contributor)

Created2020-05

Evaluating the effects of partial or full replacement of chemical fertilizer with food waste fertilizer on growth and flowering of lettuce and petunia

Description

Traditional crop production faces a significant challenge due to overapplication, mining, and decreased supply of mineral nutrients. In addition to this, the urgent need to address global food waste has become increasingly apparent, as discarded food scraps in landfills contribute to harmful greenhouse gas emissions. A promising solution that addresses both of these critical challenges includes the innovative utilization of food waste anaerobic digestate as a fertilizer for crop production. This study investigated whether using anaerobically digested food waste as fertilizer can fully replace or reduce the use of chemical fertilizer in vegetable and ornamental crop production. The seeds of lettuce (Lactuca sativa) ‘Nancy’ and petunia (Petunia × hybrida) ‘Easy Wave Velour Berry’ were sown into a soilless medium and grown in the indoor vertical farm at 22℃ under sole-source lighting at a photosynthetic photon flux density of 180 µmol∙m–2∙s–1 with a 20-h photoperiod. Four weeks after sowing, seedlings were transplanted and grown for three weeks in a greenhouse with an average daily temperature of 20 °C under ambient sunlight with an average daily light integral of 22 mol∙m–2∙d–1. The plants were fertilized using tap water mixed with different fertilizers, including a chemical fertilizer (15N-2.2P-16.6K), an organic fertilizer derived from anaerobically digested food waste (0.06N-0.026P-0.1191K), or a blend containing 50% chemical fertilizer and 50% food waste-based fertilizer, at the electrical conductivity of 0.7 mS·cm-1 during the young plant stage and 2.1 mS·cm-1 after transplant. At the young plant stage, lettuce and petunia have similar growth characteristics, including leaf number, SPAD index, and shoot and root fresh mass, when treated with either chemical or chemical + food waste fertilizer. In contrast, in both species, leaf area was 93-152% larger and fresh mass was 82-141% greater in plants treated with chemical or chemical + food waste fertilizer compared to food waste fertilizer. At the finishing stage, lettuce and petunia also showed similar growth and flowering characteristics under chemical or chemical + food waste fertilizer. However, in the lettuce finishing plants, fresh mass was 127-199% larger when supplied with chemical or chemical + food waste fertilizer compared to food waste fertilizer. In petunia, the number of flowers was 123-190% greater in chemical and chemical + food waste fertilizer compared to food waste fertilizer. In both lettuce and petunia at the finishing stage, the SPAD index, leaf number, root fresh mass, and root dry mass were similar among all treatments. These results suggest that food waste fertilizer applied as the sole source of plant nutrition is insufficient in comparison to chemical fertilizer at the same electrical conductivity. However, partially substituting some food waste fertilizer for chemical fertilizer reaps similar plant yield to chemical fertilizer on its own.

ContributorsGoode, Jasmine (Author) / Park, Yujin (Thesis director) / Chen, Zhihao (Committee member) / Barrett, The Honors College (Contributor) / School of Earth and Space Exploration (Contributor) / School of Geographical Sciences and Urban Planning (Contributor) / College of Integrative Sciences and Arts (Contributor)

Created2023-12