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- All Subjects: Sustainability
Phosphorus (P) is a limiting nutrient in ecosystems and is mainly used as fertilizer to grow food. The demand for P is increasing due to the need for increased food supply to support a growing population. However, P is obtained from phosphate rock, a finite resource that takes millions of years to form. These phosphate rock deposits are found in only a few countries. This uneven distribution of phosphate rock leads to a potential imbalance in socio-economic systems, generating food security pressure due to unaffordability of P fertilizer. Thus, the first P-sustainability concern is a stable supply of affordable P fertilizer for agriculture. In addition, improper management of P from field to fork leaves an open end in the global P cycle that results in widespread water pollution. This eutrophication leads to toxic algal blooms and hypoxic “dead zones”. Thus, the second P-sustainability concern involves P pollution from agriculture and cities. This thesis focuses on P flows in a city (Macau as a case study) and on potential strategies for improvements of sustainable P management in city and agriculture. Chapter 2 showed a P-substance-flow analysis for Macau from 1998-2016. Macau is a city with a unique economy build on tourism. The major P flows into Macau were from food, detergent, and sand (for land reclamation). P recovery from wastewater treatment could enhance Macau’s overall P sustainability if the recovered P could be directed towards replacing mined P used to produce food. Chapters 3 and 4 tested a combination of P sustainability management tactics including recycling P from cities and enhancing P-use efficiency (PUE) in agriculture. Algae and biosolids were used as recycled-P fertilizers, and genetically transformed lettuce was used as the a PUE-enhanced crop. This P sustainable system was compared to the conventional agricultural system using commercial fertilizer and the wild type lettuce. Chapters 3 and 4 showed that trying to combine a PUE-enhancement strategy with P recycling did not work well, although organic fertilizers like algae and biosolids may be more beneficial as part of longer-term agricultural practices. This would be a good area for future research.
In the first essay, I investigate the financial impact of a buyer-initiated supplier-focused sustainability improvement program on suppliers’ profitability. The results indicate that a supplier sustainability program may lead to short-term financial loss but long-term financial gain for suppliers, and this effect is contingent on supplier slack resources. The second essay of this dissertation focuses on the consumers and investigates their reactions to two types of firm environmental sustainability claims – sustainable production versus sustainable consumption. The results indicate that firm sustainable consumption claims increase consumers’ purchase, thus leads to larger firm sales, whereas firm sustainable production claims decrease consumers’ buying intention, then result in smaller firm sales. Therefore, I show that, contrary to extant belief, firm environmental sustainability can decrease consumers’ intention to buy. Finally, a firm may be impacted when some of its upstream or downstream stakeholders, or its own operations, are impacted by a natural disaster, which are becoming more frequent due to climate change. In the third essay I study the joint effect of market attention and donation timing on firm stock returns based on the experiences of firms who donated to the 2017 Hurricane Harvey. I conclude that neither the first donors nor the followers can mitigate the negative stock returns due to disasters. However, firms who match their donation timing with market attention experience less negative stock market returns compared to other counterparts.
First, it shows that social, economic, and energy insecurity creates a complex energy-poverty nexus, undermining equitable, fair, and sustainable energy futures in marginalized communities. Indirect and access-based measures of energy poverty are a mismatch for the complexity of the energy-poverty nexus. The thesis, using the concept of social value of energy, develops a methodology for systematically mapping benefits, burdens and externalities of the energy system, illustrated using empirical investigations in communities in Nepal, India, Brazil, and Philippines. The thesis argues that key determinants of the energy-poverty nexus are the functional and economic capabilities of users, stressors and resulting thresholds of capabilities characterizing the energy and poverty relationship. It proposes ‘energy thriving’ as an alternative standard for evaluating project outcomes, requiring energy systems to not only remedy human well-being deficits but create enabling conditions for discovering higher forms of well-being.
Second, a novel, experimental approach to sustainability interventions is developed, to improve the outcomes of energy projects. The thesis presents results from a test bed for community sustainability interventions established in the village of Rio Claro in Brazil, to test innovative project design strategies and develop a primer for co-producing sustainable solutions. The Sustainable Rio Claro 2020 initiative served as a longitudinal experiment in participatory collective action for sustainable futures.
Finally, results are discussed from a collaborative project with grassroots practitioners to understand the energy-poverty nexus, map the social value of energy and develop energy thriving solutions. Partnering with local private and non-profit organizations in Uganda, Bolivia, Nepal and Philippines, the project evaluated and refined methods for designing and implementing innovative energy projects using the theoretical ideas developed in the thesis, subsequently developing a practitioner toolkit for the purpose.
This PhD research examines the integration of DSM strategies in existing residential and commercial buildings in the Phoenix, Arizona metropolitan area, a hot-arid climate. The author proposes three different case studies to evaluate the effectiveness of one DSM strategy in buildings, namely the integration of Phase Change Materials (PCMs). PCMs store energy in the freezing process and use that stored energy in the melting process to reduce the energy demand. The goal of these case studies is to analyze the potential of each strategy to reduce peak load and overall energy consumption in existing buildings.
First, this dissertation discusses the efficacy of coupling PCMs with precooling strategies in residential buildings to reduce peak demand. The author took a case study approach and simulated two precooling strategies, with and without PCM integration, in two sample single-family homes to assess the impact of the DSM strategies (i.e., precooling and PCM integration) on load shifting and load shedding in each home.
Second, this research addresses the feasibility of using PCMs as sensible and latent heat storage in commercial buildings. The author documents the process of choosing buildings for PCM installation, as well as the selection of PCMs for retrofitting purposes. Commercial building case studies compare experimental and simulation results, focusing on the impact of the PCMs on reducing the total annual energy demand and energy cost.
Finally, this research proposes a novel process for selecting PCMs as energy efficiency measures for building retrofits. This process facilitates the selection of a building and PCM that are complementary. Implementation of this process has not yet been tested; however, the process was developed based on experimental and simulation results from prior studies, and it would alleviate many of the PCM performance issues documented in those studies.
The first paper of this dissertation found that divergent design intentions lead to unique trajectories for LSA, the urban heat island effect, and bird community at two urban riparian sites in the Phoenix metropolitan area. The second paper examined institutional shifts that occurred during Cuba’s “special period in time of peace” and found that the resulting land tenure changes both modified and maintained the LSA of the country, changing cropland but preserving forest land. The third paper found that globalized forces may be contributing to the homogenizing urban form of large, populous cities in China, India, and the United States—especially for the ten largest cities in each country—with implications for surface urban heat island intensity. Expanding knowledge on social drivers of land system and environmental change provides insights on designing landscapes that optimize for a range of social and ecological trade-offs.