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Sustainable Grid Integration of Distributed and Renewable Resources

Trainee Research Abstracts

Water Constraints in the Energy Sector - Margaret Cook (with Prof. Michael Webber)

Margaret's masters research as part of the Energy-Water Nexus focuses on the effects of drought and heat wave on thermoelectric power generation and fuel extraction.

Water constraints affect power plants in many ways. Recent droughts and heat waves have revealed the vulnerability of some power plants to effects from higher temperature intake water for cooling. To avoid heating the cooling water beyond temperature thresholds set by the EPA, some plants have been forced to reduce their power generation. At the same time, future warming of water resources from heat waves, droughts, or climate change might increase water temperatures, especially during summer months when power demand reaches its peak. In her research, Margaret seeks to model and predict which plants would have the greatest risk of de-rating due to thermal discharge limits and higher temperatures.

Water constraints also affect the oil and gas sector. Under certain political and economic conditions, the high purchasing price for water for use in hydraulic fracturing could encourage more efficient water use in the oil and gas sector, as well as in other water use sectors intending to trade their water rights. The high price of water creates opportunities for water trading while increased water efficiency in the selling sector increases the volume available for trading. Moreover, payments for water could also cover the costs of more water-efficient technologies in these sectors. The high purchasing price also encourages more efficient water use in the oil and gas sector. Under certain political and economic conditions, reuse and recycling then become feasible. In her research, Margaret assesses the water market in Texas, including the changing political and economic conditions that could encourage or discourage efficient water use.

Benefits and challenges of high penetration of solar photovoltaic generation in the Texas electricity grid - Thomas Deetjen (with Prof. Michael Webber)

As solar photovoltaic (PV) technology becomes less expensive and society focuses on cleaner energy sources, the Electric Reliability Council of Texas (ERCOT) will see a greater amount of installed solar PV generation in the electric grid. Our research aims to understand the benefits and challenges associated with a large amount of solar PV generation in ERCOT and to recommend technologies and policies which will improve its integration into the grid.

In order to observe the market effects of solar PV generation, our research group has created a unit commitment and dispatch (UC&D) model of ERCOT. The UC&D algorithm uses generator information, fuel costs, and market structures to decide how much electricity each generator should produce in order to meet electricity demand at the lowest overall system cost. We use this model to simulate different amounts, locations, and orientations of solar PV generation in ERCOT in order to understand how it affects the market. This provides insight into the benefits and challenges associated with large amounts of solar PV generation.

Understanding the challenges of integrating solar PV generation into the electric grid allows us to test how different technologies and policies might facilitate its integration. We will explore how electricity storage, demand response, carbon taxation, and other strategies synergize with solar PV generation and whether or not they can help reduce its disadvantages and improve its benefits. These results will communicate what our future electricity markets might look like and how we can plan for that trajectory.

Electrochemical Determination and Speciation of Mercury in Aqueous Systems James Grundy (with Prof. Lynn Katz)

Mercury is a unique heavy metal in that it can be transported across the globe due to the volatility of elemental mercury. Coal-fired power plants are a major source of mercury emission into the atmosphere. From the atmosphere, mercury gets deposited to terrestrial and aquatic environments through airborne particles and precipitation. In aqueous environments, mercury transforms into more toxic methylmercury by microbes in anoxic conditions, which are often found in aquatic sediments. Organic methylmercury bioaccumulates and biomagnifies, meaning that the toxic effects of methylmercury are felt by organisms near the top of the food chain, including humans. As cleaner sources of electric power are more often utilized, mercury emissions will decrease, but issues pertaining to historic mercury contamination will persist.

 

Remediation of mercury-impacted sediments requires routine monitoring to assess the efficacy of the treatment option. One important monitoring parameter that is often overlooked due to cost or sampler availability is mercury, both inorganic and methylmercury, in surface water and sediment porewater. This research focuses on developing a robust microelectrode and method capable of ultra-low detection of both mercury (II) and methylmercury in-situ using electrochemical methods, such as anodic stripping voltammetry. Development of such an electrode could improve site assessment datasets and reduce environmental monitoring costs by providing accurate, real-time data to decision makers. In addition to sediment remediation scenarios, the electrode system could be used for real-time monitoring of drinking water supplies, from a public-utility scale to drinking water wells for single family homes.

 

Photoelectrochemical Hydrogen Production - Oluwaniyi Mabayoji (with Prof. C.B. Mullins)

Rising concerns over pollution and increasing world temperatures due to the continued use of fossil fuels has led to a search for alternative fuels. Apart from its impact on the environment, the continued reliance on fossil fuels may be impractical as these rapidly depleting resources will be unable to keep up with demand in the near future. An ideal alternative fuel would be derived from renewable and cheap resources in processes that are cost-efficient and environmentally benign. One such fuel that is being considered is hydrogen. The conversion of solar energy to chemical energy in hydrogen is attractive for many reasons: it is essentially a nonpolluting, carbon free fuel and it can be made from abundant resources – solar energy and water. Photoelectrochemical water splitting is thus an attractive form of hydrogen production. More specifically the system desired would produce hydrogen at room temperature using light from the solar spectrum. The hydrogen can then be used in fuel cells or as chemical feedstock.

Water-splitting involves two reactions – the hydrogen and oxygen evolution reaction (HER and OER). The mechanism of both the HER and the OER are yet to be fully elucidated. Both reactions, especially the OER, involve numerous intermediates and steps. This makes the possibility of designing specific and efficient electrocatalysts a daunting task. We are able to use thermodynamics and electrochemical principles along with predictive tools in selecting possible electrocatalytic combinations of mixed-metals, mixed-metal sulfides and mixed metal oxides catalysts for both the HER and the OER. Once selected varying compositions of these materials are quickly synthesized using a computer-controlled piezoelectric dispenser. The photoelectrode with the deposited array is then tested in a three electrode cell and a fiber optic tip connected to a xenon lamp is rastered across the array while the photocurrent from each composition is measured.

Semiconductors/light absorbers can also be discovered using this dispenser-scanner system. The speed of synthesis and testing used in this system would go a long way in the discovery of materials that can serve as catalysts or light absorbers for the water-splitting reaction.

Combined Heat and Power for Residential Neighborhoods: Data-Driven Modeling, Optimization, and Control - Abigail Ondeck (with Prof. T.F. Edgar and Prof. Michael Baldea)

Approximately 20% of the electricity produced in the United States is used in the residential sector, with about half of this energy going to heating, ventilation, and air-conditioning (HVAC) systems. Coal-fired power plants, which provide the majority of the electricity, have very high CO2 emissions and among the lowest efficiencies of all power generation facilities. One way to reduce CO2 emissions and increase efficiency in the residential sector is to combine electricity generation and steam and chilled water for heating/cooling into a local neighborhood-level CHP plant with a cleaner fuel source. There are currently no CHP plants in the United States that provide integrated utilities to residential neighborhoods, and studies exploring such opportunities are not available. However, there are CHP plants currently in the United States and around the world that serve large commercial areas with many businesses and apartments in close quarters. These plants, such as such as Austin Energy's Mueller Energy Center, the University of Texas – Austin CHP, and Dubai Motor City, provide electricity, steam, and chilled water to larger buildings, hotels, and medical centers, and require large plants to meet energy demands. Europe has established the Euroheat & Power group to promote the use of CHP and District Heating and Cooling (DHC) in over 30 countries, but have only started installing district cooling in older residential neighborhoods. The United States has yet to conduct major research on integration of CHP plants and district cooling into strictly residential neighborhoods.

The goal of my research is to determine the optimal integration of a CHP plant as a utility producer for a residential neighborhood, and the potential for using photovoltaics, implemented in a centralized fashion, to alleviate fluctuations in residential electricity demand. Utilizing data provided by WikiEnergy, residential heating, cooling, and electricity demand are analyzed and evaluated. These data are then used to create a time-resolved energy profile of residential energy use and the operation of a CHP plant as the sole utility provider for the residential neighborhood. The impact of integrated photovoltaics on the hourly operation of the plant is also identified.

Residential adoption of decentralized energy resources in contexts with social, economic, and physical infrastructure networks - D. Cale Reeves (with Prof. Varun Rai)

Residential solar PV adopters face a decision-making environment characterized by high costs – composed of the monetary cost of adoption as well as uncertainty and non-monetary costs (UNMCs) associated with the search for information and the future performance of the system – in addition to other factors. Federal, state, and local rebate programs attempt to accelerate residential solar PV adoption by offsetting a portion of the monetary costs faced by consumers. Adopters attempt to overcome the complexity introduced by other social and behavioral factors – including peer effects, anchoring, loss aversion, and path dependence – by consulting trusted information sources. To understand the adoption process, we must jointly study these economic, social, and behavioral factors in the context of the exchange of information between adopters and would-be adopters.

A recently developed agent-based model (ABM) of residential solar PV diffusion predicts adoptions over space and time with a high degree of accuracy in part by simulating the propagation of attitudes towards solar through peer effects among small-world networks of households. Participants (nodes) in social networks such as these have differing levels of influence on one another. So-called "opinion leaders" and "hubs" are social mavens; they have a greater impact on the attitudes of connected nodes by virtue of exerting a stronger influence or by having ties to more nodes. I use ABM to experimentally manipulate information seeding strategies and explore underpinning social network structures in search of social mavens, and then simulate the effect of information campaigns targeted to them.

Socio-environmental Impacts and Geopolitical Implications of Oil & Natural Gas Exploration In Rural Texas Colonias within the Eagle Ford ShaleAndrea Christina Wirsching (with Prof. Bjorn Sletto)

Currently, political and academic discussions focus on the water resource and infrastructure implications of energy production; innovations in extractive processes and supportive policy instruments; the development of more sustainable energy production, like the use of grey water in power plants or chemical-free water in hydraulic fracturing; and the establishment of new energy distribution systems, like the development and implementation of smart grid technologies. In my research, I propose to contribute new, critical perspectives to these discussions. I am interested in studying the social and environmental impacts of the drilling of the Eagle Ford Shale (EFS) on particularly vulnerable communities, specifically the colonias, in La Salle, Demit, Maverick and Webb counties. Since many of these communities have inadequate municipal services and infrastructure, the recent drilling of the EFS has significantly reshaped the local colonia landscape. The influx of the drilling companies with their workforces has placed great pressure on these limited infrastructure services, leading to water and air quality degradation, decreases in available housing, severe strains on public services, and rapid, unpredictable social changes. In addition, the construction of new roads, highways and pipelines to support extraction and associated activities has led to significant, visible changes in the landscape. By approaching the study of energy production and water resource management through interdisciplinary, yet complimentary epistemological frameworks, I seek to illuminate the nuanced, complex relationships of these social and environmental dimensions at multiple scales in ways that previous research has yet to achieve.