Our study calculates the estimated difference in water use, energy demands, and CO2 emissions of head lettuce associated with the production (land preparation and growing operations, chemical inputs, irrigation) and the transportation (diesel demand) to the Phoenix metro area from:
       1. A local level, defined here as within Maricopa County, Arizona (AZ).
       2. From the central coast of California (CA) in Monterey County.

Our research results demonstrate that local lettuce is more resource intensive than non-local or regional produce. Production in Maricopa County has significantly higher (more than double) energy demands and emissions than Monterey County. Irrigation and chemical inputs are the greatest contributors to energy demand in Maricopa, but it is primarily irrigation that contributes to emissions. Comparatively, transportation and chemical inputs are the greatest contributors to energy demand in Monterey, and it is primarily transportation that contributes to emissions.

This life cycle inventory suggests that we need to reconsider the “food miles” framing of the local food debate and whether local food production is a viable sustainable alternative to the current food system in the arid Southwest. However, we also recognize that factors beyond resource-use and emissions affect policymakers’ and consumers’ demands for local foods. Future studies ought to provide a more nuanced look at the issue that also includes social, psychological, and economic factors that influence food policies and purchases. These results have important implications for future water management and suggest the need to pursue more water efficient practices in AZ.

Study Background: Researchers at ASU have determined that significant energy and environmental benefits are possible in the Phoenix metro area over the next 60 years from transit-oriented development along the current Valley Metro light rail line. The team evaluated infill densification outcomes when vacant lots and some dedicated surface parking lots are repurposed for residential development. Life cycle building (construction, use, and energy production) and transportation (manufacturing, operation, and energy production) changes were included and energy use and greenhouse gas emissions were evaluated in addition to the potential for respiratory impacts and smog formation. All light rail infill scenarios are compared against new single family home construction in outlying areas.

Overview of Results: In the most conservative scenario, the Phoenix area can place 2,200 homes near light rail and achieve 9-15% reductions in energy use and emissions. By allowing multi-family apartments to fill vacant lots, 12,000 new dwelling units can be infilled achieving a 28-42% reduction. When surface lots are developed in addition to vacant lots then multi-family apartment buildings around light rail can deliver 30-46% energy and environmental reductions. These reductions occur even after new trains are put into operation to meet the increased demand.

Better methods are necessary to fully account for anthropogenic impacts on ecosystems and the essential services provided by ecosystems that sustain human life. Current methods for assessing sustainability, such as life cycle assessment (LCA), typically focus on easily quantifiable indicators such as air emissions with no accounting for the essential ecosystem benefits that support human or industrial processes. For this reason, more comprehensive, transparent, and robust methods are necessary for holistic understanding of urban technosphere and ecosphere systems, including their interfaces. Incorporating ecosystem service indicators into LCA is an important step in spanning this knowledge gap.

For urban systems, many built environment processes have been investigated but need to be expanded with life cycle assessment for understanding ecosphere impacts. To pilot these new methods, a material inventory of the building infrastructure of Phoenix, Arizona can be coupled with LCA to gain perspective on the impacts assessment for built structures in Phoenix. This inventory will identify the origins of materials stocks, and the solid and air emissions waste associated with their raw material extraction, processing, and construction and identify key areas of future research necessary to fully account for ecosystem services in urban sustainability assessments. Based on this preliminary study, the ecosystem service impacts of metropolitan Phoenix stretch far beyond the county boundaries. A life cycle accounting of the Phoenix’s embedded building materials will inform policy and decision makers, assist with community education, and inform the urban sustainability community of consequences.

This study aims to quantify the environmental impacts of a hospital’s daily BMW disposal in the Phoenix, Arizona area. The sole option to dispose of BMW in Arizona is to sterilize the waste by sending it through an autoclave, and then dispose the sterilized waste in a landfill. This study used a Phoenix area hospital to create a start point for the waste and a general estimation of how much BMW the hospital disposes of. The system boundary for the LCA includes BMW generated at the Phoenix-area Hospital as it is travels to Stericycle, where it is autoclaved, and then transported to a landfill for disposal. The results of this retrospective, end-of-life LCA using this boundary enables hospital employees and policy makers to understand the environmental impact of placing items in the biohazardous waste bin.

In recent years, concerns have grown over the risks posed by climate change on the U.S. electricity grid. The availability of water resources is integral to the production of electric power, and droughts are expected to become more frequent, severe, and longer-lasting over the course of the twenty-first century. The American Southwest, in particular, is expected to experience large deficits in streamflow. Studies on the Colorado River anticipate streamflow declines of 20-45% by 2050. Other climactic shifts—such as higher water and air temperatures—may also adversely affect power generation. As extreme weather becomes more common, better methods are needed to assess the impact of climate change on power generation. This study uses a physically-based modeling system to assess the vulnerability of power infrastructure in the Southwestern United States at a policy-relevant scale.

Thermoelectric power—which satisfies a majority of U.S. electricity demand—is vulnerable to drought. Thermoelectric power represents the backbone of the U.S. power sector, accounting for roughly 91% of generation. Thermoelectric power also accounts for roughly 39% of all water withdrawals in the U.S.—roughly equivalent to the amount of water used for agriculture. Water use in power plants is primarily dictated by the needs of the cooling system. During the power generation process, thermoelectric power plants build up waste heat, which must be discharged in order for the generation process to continue. Traditionally, water is used for this purpose, because it is safe, plentiful, and can absorb a large amount of heat. However, when water availability is constrained, power generation may also be adversely affected. Thermoelectric power plants are particularly susceptible to changes in streamflow and water temperature. These vulnerabilities are exacerbated by environmental regulations, which govern both the amount of water withdrawn, and the temperatures of the water discharged. In 2003, extreme drought and heat impaired the generating capacity of more than 30 European nuclear power plants, which were unable to comply with environmental regulations governing discharge temperatures. Similarly, many large base-load thermoelectric facilities in the Southeastern United States were threatened by a prolonged drought in 2007 and 2008. During this period, the Tennessee Valley Authority (TVA) reduced generation at several facilities, and one major facility was shut down entirely. To meet demand, the TVA was forced to purchase electricity from the grid, causing electricity prices to rise.

Although thermoelectric power plants currently produce most of the electric power consumed in the United States, other sources of power are also vulnerable to changes in climate. Renewables are largely dependent on natural resources like rain, wind, and sunlight. As the quantity and distribution of these resources begins to change, renewable generation is also likely to be affected. Hydroelectric dams represent the largest source of renewable energy currently in use throughout the United States. Under drought conditions, when streamflow attenuates and reservoir levels drop, hydroelectric plants are unable to operate at normal capacity. In 2001, severe drought in California and the Pacific Northwest restricted hydroelectric power generation, causing a steep increase in electricity prices. Although blackouts and brownouts were largely avoided, the Northwest Power and Conservation Council estimated a regional economic impact of roughly $2.5 to $6 billion. In addition to hydroelectric power, it has also been theorized that solar energy resources may also be susceptible to predicted increases in surface temperature and atmospheric albedo. One study predicts that solar facilities in the Southwestern U.S. may suffer losses of 2-5%.

The aim of this study is to estimate the extent to which climate change may impact power generation in the Southwestern United States. This analysis will focus on the Western Interconnection, which comprises the states of Washington, Oregon, California, Idaho, Nevada, Utah, Arizona, Colorado, Wyoming, Montana, South Dakota, New Mexico and Texas. First, climactic and hydrologic parameters relevant to power generation are identified for five types of generation technologies. A series of functional relationships are developed such that impacts to power generation can be estimated directly from changes in certain meteorological and hydrological parameters. Next, climate forcings from the CMIP3 multi-model ensemble are used as inputs to a physically-based modeling system (consisting of a hydrological model, an offline routing model, and a one-dimensional stream temperature model). The modeling system is used to estimate changes in climactic and hydrologic parameters relevant to electricity generation for various generation technologies. Climactic and hydrologic parameters are then combined with the functional relationships developed in the first step to estimate impacts to power generation over the twenty-first century.

Phoenix is the sixth most populated city in the United States and the 12th largest metropolitan area by population, with about 4.4 million people. As the region continues to grow, the demand for housing and jobs within the metropolitan area is projected to rise under uncertain climate conditions.

Undergraduate and graduate students from Engineering, Sustainability, and Urban Planning in ASU’s Urban Infrastructure Anatomy and Sustainable Development course evaluated the water, energy, and infrastructure changes that result from smart growth in Phoenix, Arizona. The Maricopa Association of Government's Sustainable Transportation and Land Use Integration Study identified a market for 485,000 residential dwelling units in the urban core. Household water and energy use changes, changes in infrastructure needs, and financial and economic savings are assessed along with associated energy use and greenhouse gas emissions.

The course project has produced data on sustainable development in Phoenix and the findings will be made available through ASU’s Urban Sustainability Lab.

As average temperatures and occurrences of extreme heat events increase in the Southwest, the water infrastructure that was designed to operate under historical temperature ranges may become increasingly vulnerable to component and operational failures. For each major component along the life cycle of water in an urban water infrastructural system, potential failure events and their semi-quantitative probabilities of occurrence were estimated from interview responses of water industry professionals. These failure events were used to populate event trees to determine the potential pathways to cascading failures in the system. The probabilities of the cascading failure scenarios under future conditions were then calculated and compared to the probabilities of scenarios under current conditions to assess the increased vulnerability of the system. We find that extreme heat events can increase the vulnerability of water systems significantly and that there are ways for water infrastructure managers to proactively mitigate these vulnerabilities before problems occur.