Browsing by Author "Patiño-Echeverri, Dalia"
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Item Open Access A bottom-up electricity demand model for the residential sector in Querétaro, Mexico(2016-12-12) Hernandez, Mauricio; Cao, SunzheThere is a growing interest in reducing energy consumption and its associated greenhouse gas emissions from every sector of the economy. The residential sector is a substantial consumer of energy in every country and understanding which factors affect the energy consumption in this sector is crucial for policy makers, investors, utilities, and other stakeholders. This study contributes to a better understanding of these factors through a case study in Queretaro, Mexico. Particularly, this study sheds light on two different methods for collecting detailed information on the end uses of energy in homes, and for assessing the relationship between energy consumption and demographic and socioeconomic indicators. The data used for this study were collected through face-to-face surveys in 32 households and by tracking real-time electricity consumption in a subset of these households. Finally, a bottom-up model was used to estimate the electricity demand of the households surveyed, with the results suggesting a correlation with income, number of lightbulbs, dwelling size, and the number of days the household was occupied. The results of the study motivated the authors to recommend the extension and replication of this study, to assess the role of private transportation in energy consumption, and to improve the use of technology for the collection and analysis of data.Item Open Access A Bottom-Up Model of Residential Electricity Demand in North and South Carolina(2017-04-28) Hollis, JohnResidential electricity is a significant component of total electricity use in the United States, and the residential market is also a key demographic for energy efficiency (EE) and distributed generation growth. Uncertainty in residential load growth is driven by the impact of changes in technology, policy, demographic and life-style changes. Using a bottom-up engineering model, we begin the construction of a tool to facilitate analyzing the effects of these factors. We use data from the EIA’s Residential Electricity Consumption Survey (RECS), in conjunction with EnergyPlus and BEopt, publicly available software from NREL, to construct 22 archetypical residential buildings characterizing North and South Carolina’s housing stock. We then model energy use for these buildings, and extrapolate these results to the larger housing stock. Projections are accurate for a benchmark year using actual weather data. We identify a number of potential improvements to the model and ways in which the uncertainty on future projections of energy use can be bound. Our conclusions follow: - The archetypical model is a reasonable solution for regional scale residential electricity modeling which minimizes computational needs. - The model delivers disaggregated energy demand, and hourly demand, estimates which are useful for future analysis of energy policy cost effectiveness. - Weather data is a driving source of uncertainty, and hence input weather data should be carefully considered. Projections should use varied weather data to bound uncertainty. - Despite being less computationally demanding than other methods, this model would benefit from an automated method of archetype alteration to ease sensitivity analysis. BEopt supports this through python and XML input files.Item Open Access A Case Study of Community Solar’s Impact on the Energy Affordability of Minnesota’s Low to Moderate Income households(2020-04-24) Jung, AnnieCommunity solar gardens have been adopted by many states in the United States of America. They are an innovative way for utility ratepayers to have a direct role in the energy transition and support deployment of solar power onto the grid. However, the renewable energy industry has been criticized for the lack of low-to-moderate income household participation. To examine this further, I analyzed the participation rate of low-to-moderate income households in a sample set of Minnesota community solar subscriber data. This was achieved by translating the threshold for low-to-moderate income households to a housing price value. Furthermore, a model was created to assess the financial impact of various community solar tariffs on all the stakeholders involved. Analysis of data from 306 credit scores and 185 addresses of community solar garden subscribers showed that even with a credit score minimum requirement, almost 31% of subscribers were low-to-moderate income households. The results of the model showed that non-subscribing ratepayers pay at least 5% more in annual utility bills than subscribers, regardless of their income level. I also found that utilities and developers have competing interests when setting community solar tariffs, even after the Value of Solar was implemented. Overall, these findings support the low-to-moderate income ratepayer advocates and arguments for community solar reform.Item Open Access A COMPARISON OF MARKET CLEARING TOOLS IN ELECTRICITY SYSTEMS(2015-04-23) Li, XinTo maintain a strict balance between demand and supply in the US power systems, the Independent System Operators (ISOs) schedule power plants and determine electricity prices using a market clearing model. This model determines for each time period and power plant, the times of startup, shutdown, the amount of power production, and the provisioning of spinning and non-spinning power generation reserves, etc. Such a deterministic optimization model takes as input the characteristics of all the generating units such as their power generation installed capacity, ramp rates, minimum up and down time requirements, and marginal costs for production, as well as the forecast of intermittent energy such as wind and solar, along with the minimum reserve requirement of the whole system. This reserve requirement is determined based on the likelihood of outages on the supply side and on the levels of error forecasts in demand and intermittent generation. With increased installed capacity of intermittent renewable energy, determining the appropriate level of reserve requirements has become harder. Stochastic market clearing models have been proposed as an alternative to deterministic market clearing models. Rather than using a fixed reserve targets as an input, stochastic market clearing models take different scenarios of wind power into consideration and determine reserves schedule as output. Using a scaled version of the power generation system of PJM, a regional transmission organization (RTO) that coordinates the movement of wholesale electricity in all or parts of 13 states and the District of Columbia, and wind scenarios generated from BPA (Bonneville Power Administration) data, this paper explores a comparison of the performance between a stochastic and deterministic model in market clearing. The two models are compared in their ability to contribute to the affordability, reliability and sustainability of the electricity system, measured in terms of total operational costs, load shedding and air emissions. The process of building the models and running for tests indicate that a fair comparison is difficult to obtain due to the multi-dimensional performance metrics considered here, and the difficulty in setting up the parameters of the models in a way that does not advantage or disadvantage one modeling framework. Along these lines, this study explores the effect that model assumptions such as reserve requirements, value of lost load (VOLL) and wind spillage costs have on the comparison of the performance of stochastic vs deterministic market clearing models.Item Open Access A Geospatial Approach to Siting Wind Right in the Southeast(2021-04-29) Feng, Xueying; Li, ShawnWhile installed wind turbine capacity continues to increase in the United States, a noticeable void exists in the Southeast due to a combination of poor wind resources, competing energy sources, and political opposition. As manufacturers develop turbines with a higher hub height to harness faster and smoother wind resources, many, including The Nature Conservancy, anticipate significant wind development in the Southeast. The identification of low environmental impact areas will not only lower the risk of project development but will also enable the identification of priority areas for transmission and distribution infrastructure. To capitalize on the opportunity to site wind right from the beginning, this study uses a GIS-based exclusion category approach to identify areas where installed wind power capacity is least likely to disrupt wildlife and sensitive habitats. The geospatial model creates maps where environmental and technical areas that are unsuitable for wind farms are removed. The model considers a sequence of five categories of land exclusion criteria. The resulting geospatial product suggests that even after removing sizable areas from consideration, there is significant land for wind development to meet the energy and climate needs of the Southeast region.Item Open Access A Modeling Tool for Fuel Price Risk Management in Power Generation Portfolio Planning(2012-04-25) Sercy, KennethPower plants are significant capital investments whose returns are largely determined by such uncertain factors as future fuel prices and environmental regulations. Traditionally regulated utilities in the United States initiate power plant investment decisions through a process called Integrated Resource Planning (IRP). The aim of this centralized planning approach is to comprehensively assess both supply-side and demand-side options for satisfying load in the utility’s service territory over the next 20-30 years, and to establish a road map of actions that will serve load at least cost while adhering to reliability standards. Given the current level of uncertainty associated with many types of power plant investments, industry experts have identified a need for innovative planning practices within the IRP framework that can highlight resource tradeoffs, consider a variety of outcome metrics, and test a broader range of resource portfolios. This document describes the development and evaluation of a decision tool that is capable of capturing the tradeoff between upfront capital costs and fuel price risk in power plant investment decisions. An adaptation of mean-variance portfolio theory (MVP), a financial risk management framework, serves as the foundation of the model. As an extension of previous applications of MVP to power sector planning, this project explores the potential for implementing a parametric approach to fuel price inputs as well as a multi-period decision structure. The decision tool is evaluated under five input scenarios that represent different possible future fuel price trajectories and greenhouse gas emissions concerns. Results suggest that the parametric fuel price modeling methodology demonstrated here may be a valuable approach to future IRP applications of MVP. The multi-period structure is problematic in that outputs cannot be compiled across periods. Additionally, use of a widely accessible but computationally limited software platform precludes sufficient representation of economies of scale in power plant construction. Although these drawbacks may limit MVP applications to the exploratory analysis phase of IRP, with further development, the decision tool developed here could be useful in addressing some of the limitations of current IRP practices with respect to decision-making under uncertainty.Item Open Access Adapting Master Limited Partnerships as a Policy Option for the Renewable Energy Industry(2012-04-25) Sorice, JeannetteItem Open Access An Analysis of Power Content Label Designs(2010) Wolfinger, Jan FelixThere are currently 22 states with full or partial disclosure requirements for their electricity suppliers. These requirements differ significantly across states, in terms of the specific information content, structure, and presentation, but all have the potential of increasing customers' awareness about the links between their electricity consumption and air emissions, and perhaps create incentives for utilities to reduce those emissions or for customers to reduce their consumption or to switch to a different electricity supplier.
How effective this policy has been is still unclear. The main criterion for effective communication strategies is that they include relevant information for the readers in a usable form. Information needs as well as the ability to process and apply it vary significantly across individuals. However, people are limited in their information-processing capabilities. Policy makers therefore face the trade-off between a large amount of potentially relevant information that ideally needs to be included on the label on the one hand, and decrease in usability as more information is included on the label, on the other.
This paper examines the design, readability and usability of sample labels from 18 different states with information disclosure requirements. The labels are compared and rated according to how they balance the two main dimensions of label design, information content and usability, demonstrating the difficult trade-off between the two. In addition to this, the labels are analyzed along several key aspects: information load, focus on environmental impact, comparability, understandability, and materiality of information. As part of the analysis, measures for these different aspects of label effectiveness are created. The main finding of the analysis is that there are difficult trade-offs between information content and label usability. However, this trade-off can partially be avoided by carefully designing the labels, easing the cognitive burden of users while still conveying relevant information to the decision maker.
The results of the analysis can help evaluate the various existing disclosure policies, and offer approaches to improve upon them. It will also be shown that while preferred levels of information content are incommensurate with maximum usability, certain structures and form elements succeed at making more complex information content easier to use, improving the overall performance of the labels.
Item Open Access An Ecologically Focused Guide to Community Solar Siting and Development(2024-04-25) Bowlin, Isaac; Dye, Logan; Freedman, JacobThe rapid expansion of utility-scale solar energy (USSE) development presents a significant challenge to achieving renewable energy goals while minimizing impacts on land use and wildlife. Current USSE siting practices prioritize efficient and cost-effective development strategies that do not adequately consider ecological impacts. This problem necessitates the development of ecologically friendly siting and facility arrangement strategies that minimize the effects of solar development on ecosystems and wildlife while promoting sustainable land use practices. However, the best management practices needed to achieve these objectives are still quite ambiguous, with minimal research conducted to quantify wildlife impacts and provide clear guidelines for policy implementation. Distributed solar generation (DSG) presents an alternative development strategy, generating electricity close to demand centers using smaller, localized solar arrangements. Community solar, a specific form of DSG, exemplifies this decentralized approach by allowing multiple community members to collectively benefit from a shared solar installation, expanding access to clean energy while reducing land use impacts. In partnership with The Nature Conservancy and Highline Renewables, our research analyzes the known implications of USSE, the potential for DSG to improve habitat connectivity, and the state policies enabling innovative community solar siting practices. This report seeks to inform researchers, policymakers, and solar developers of policy frameworks and development practices that prioritize sustainable solar development. Chapter 1 conducts a literature review on the known ecological impacts of USSE development, informing ecologists about and encouraging solar developers to employ low-impact siting strategies. Chapter 2 performs a novel, standalone geospatial analysis demonstrating how various solar facility arrangements and siting locations impact bobcat (Lynx rufus) connectivity. This analysis can help developers make informed decisions regarding solar facility placement and reinforces the need for policy frameworks that enable DSG. Next, in Chapter 3, we review current and emerging state community solar markets and provide recommendations to policymakers for designing future policies. Finally, in Chapter 4, we examine the role of agrivoltaics, the integration of solar generation with agricultural activities, as a strategy for developers to reduce solar facility land use impacts. Our Chapter 1 literature review found that USSE facilities cause direct mortality to aquatic insects, birds, and bats while altering the movement and connectivity of ground-dwelling animals such as Pronghorn (Antilocapra americana) and Florida Panthers (Puma concolor). However, significant knowledge gaps exist in understanding these impacts—notably, the lack of Before-After-Control-Impact (BACI) studies and the limited geographic scope of research. Nearly 50% of the existing U.S. research has been conducted in the desert southwest, severely limiting the ability to extrapolate findings to the broader U.S. Wildlife-friendly fencing and vegetation management can help maintain suitable habitat; however, these solutions must be studied in other regions to assess their effectiveness. The geospatial analysis conducted in Chapter 2 reveals that both siting practices and spatial arrangement of solar facilities greatly impact species movement across a landscape. By analyzing how the predicted movement patterns of bobcats in southeast Ohio responded to both a USSE development in Dixon Run and the theoretical redistribution of Dixon Run’s generation capacity, we found that by redistributing capacity across the landscape, impacts on bobcat movement are reduced. However, a sensitivity analysis revealed that the locations of the distributed solar were in areas already deemed poor habitat for bobcats. That said, it is important to note that relocation of a USSE facility the size of Dixon Run to the areas considered poor bobcat habitat was practically impossible. Small, localized installations were the only way to build in these areas. Our policy analysis reveals significant variation among individual state community solar markets in the size of allowable projects, subscriber composition, and siting practices they encourage. Maryland and Ohio demonstrate different approaches to community solar policy, with Maryland emphasizing reducing barriers to low and moderate-income (LMI) participation, while Ohio promotes solar development on distressed sites and brownfields. Notably, state community solar markets often lack specific incentives that promote low-impact siting practices that minimize the solar facility’s impact on the local habitat. To improve future community solar legislation, policymakers should offer grants, tax credits, and other financial incentives that prioritize the preservation of existing topsoil and vegetation, site away from ecologically sensitive areas, and support innovative land use practices, including agrivoltaics. Implementing agrivoltaics offers a promising solution to reducing the siting impacts of USSE facilities and the competing land demands for agricultural production and solar development. The literature reviewed demonstrates that agrivoltaic systems can benefit agricultural productivity, land use efficiency, panel efficiency, and livestock and ecosystem health. Agrivoltaic systems offer the greatest benefits under specific conditions, specifically hot and dry climates, where the shading provided by panels mitigates the effects of excessive heat and water stress on crop productivity and livestock well being. However, the efficacy of agrivoltaic systems can vary and is contingent upon various factors such as shading distribution, crop sensitivity, and environmental conditions. Future research into agrivoltaics should focus on optimizing system design, evaluating financial performance, and fostering landowner engagement to ensure the successful implementation of this innovative approach to land use.Item Open Access An Evaluation of Current and Future Costs for Lithium-Ion Batteries for Use in Electrified Vehicle Powertrains(2009-04-24T16:53:28Z) Anderson, DavidPowertrain electrification is a concept which encompasses hybrid-electric vehicles (HEVs), plug-in hybrid-electric vehicles (PHEVs), and pure electric vehicles (EVs). Such vehicles have received attention recently as a potential solution for reducing the carbon intensity of the transportation sector. The fundamental challenge to the commercial success of electrified vehicles is energy storage. Consensus in the automotive industry is that lithium-ion (Li-ion) batteries are the most likely candidate for overcoming this challenge in the next decade. However, these batteries must meet five categories of goals in order for them to enable the success of electrified vehicles: energy, power, lifetime, safety, and cost. Of these five goals, cost may be the most uncertain, and perhaps the most critical. This research examines the primary cost drivers for automotive Li-ion batteries at the cell-, module-, and pack-level. It then investigates how these costs may change over the next two decades, and what impact this may have on the cost-competitiveness of electrified vehicles. This is accomplished through the development of a bottom-up cost model that considers the materials cost, manufacturing cost, and other costs such as corporate overhead and research and development that contribute to overall Li-ion battery costs. Two scenarios of how these costs may change are developed: an optimistic case and a pessimistic case. Additionally, the level to which battery costs must decline in order for vehicles of varying levels of powertrain electrification to become economically competitive with their conventional internal combustion engine counterparts is calculated. Results indicate that the primary cost drivers for Li-ion batteries at the pack-level are cell-level materials cost and manufacturing yields. Improvements in these areas will be key drivers for reductions in overall battery costs, and may make electrified vehicles cost-competitive with conventional automobiles. However, this cost-competitiveness is highly sensitive to fuel prices. Various policy and market mechanisms can significantly impact the economic viability of electrified vehicles and influence the rate at which they are adopted.Item Open Access An interdisciplinary assessment of alternatives for the decarbonization of the electric power sector: Integrating operations research and geospatial analysis to identify cost-efficient strategies for the energy transition(2022) Virguez, EdgarA cost-effective pathway towards net-zero electric power systems requires an extraordinary deployment of new solar and wind generation assets. This aggressive expansion driving unprecedented investment entails a fundamental understanding of the challenge ahead of us. This dissertation seeks to provide a multidisciplinary perspective of research questions that shine the light on rapid and cost-efficient strategies for the energy transition. Integrating operations research and geospatial analysis methods, the dissertation utilizes a multidisciplinary approach when addressing three questions.
First, the dissertation examines the role of battery energy storage technologies (i.e., utility-scale lithium-ion batteries) on reducing the greenhouse gas emissions of an electric power system while simultaneously achieving a reduction in carbon abatement costs. The study uses a cost-based production model (day-ahead unit commitment and a real-time economic dispatch) to simulate the optimal operation of all the generation resources in the largest vertically-integrated electric service region in the U.S. The study explores a multitude of configurations to identify optimal sizing of battery energy storage systems when paired with utility-scale photovoltaics.
Next, the dissertation studies the effect of incorporating high-resolution data when identifying suitable land for renewable energy projects over a geographically defined region. Using a python-based user-friendly siting tool implemented in ArcGIS Pro to perform suitability and cost analysis of utility-scale photovoltaic projects in North Carolina under three scenarios (representing conditions ranging from favorable to restrictive). The study finds that the land suitable for utility-scale photovoltaics reduces substantially when parcel-level data reflecting local land-use restrictions are incorporated. The study's findings highlight the necessity of integrating detailed land-use data that reflects local regulation (zoning ordinances) into siting models while simultaneously increasing their spatial granularity.
Lastly, the dissertation analyzes the benefits of weatherizing wind power farms enabling their operation under extreme climates (winter storms). The study uses global reanalysis data with operational information from the Electric Reliability Council of Texas (ERCOT) during the 2021 winter storm Uri to simulate a continued operation of wind power farms under low-temperature environments. The study finds that the financial benefits that winterized wind turbines would have received during winter storm Uri would have outweighed the capital costs required to implement ice-accretion mitigation actions (before winter storm URI).
Item Open Access Analyzing Household Drivers of Residential Electricity Consumption in Mexico(2020-04-24) Siegel, Jess Sonya; Ullman, Amanda; Wu, KarenIn this study, we analyze the drivers of household appliance saturation in Mexico in order to support the ongoing development of a computer-based model for long-term projections of residential electricity consumption. Our findings inform future decisions regarding energy efficiency policies and capacity expansion plans of the electric power sector. With the most carbon-intensive electricity grid in Latin America, a growing population, and a growing energy-intensive middle class, Mexico has set goals to reduce energy consumption by 30% in their residential sector by 2030. In this project, we analyze 2008-2018 data from Mexico’s National Survey of Household Income and Expenditure (ENIGH) to investigate how household characteristics have influenced the adoption of various types of HVAC, lightbulbs, televisions, washing machines, and other household appliances. Additionally, we analyze how regional and climatic differences have especially affected heating and cooling technologies. Finally, we review electricity policies in Mexico to explore their effects on appliance adoption and make recommendations for future policies. Our findings indicate that, although the saturation of each appliance is influenced to varying degrees by different factors, socioeconomic status was a common significant factor across all appliances. The country could enhance its appliance adoption and replacement programs catered towards low income communities, enforce stricter energy efficiency standards at a faster pace, and continue collecting detailed data on household energy use.Item Open Access ASSESSING THE IMPACT OF FLEXIBLE RAMP CAPABILITY PRODUCTS IN THE MIDCONTINENT ISO(2014-04-25) Cornelius, AdamIn electric power systems, balancing authorities adjust the output of dispatchable coal and natural gas generators in response to changes in net load (electricity demand minus variable generation such as wind). As penetration of renewable energy increases, so do the variability and uncertainty surrounding net load, making balancing more difficult. The flexibility of the system to ramp power output up and down (i.e. ramping capability) may be insufficient to accommodate large changes in net load, potentially leading to scarcity events and threatening system security. The Midcontinent Independent System Operator (MISO) has proposed ancillary service products called up-ramp capability (URC) and down-ramp capability (DRC) intended to increase system flexibility. The purpose of this study is to explore the economic, environmental, and reliability impacts of MISO’s proposed ramp capability products. Two versions of the unit commitment and economic dispatch processes used by MISO to optimally schedule generators were modeled: (1) a baseline model representing current MISO practices, and (2) a ramp capability model that includes the proposed products. These models were applied to a small power system representative of MISO’s mix of generators under low and high wind penetration levels. In this model the DRC product had no impact, indicating that the representative power system was more flexible in the downward direction than MISO’s actual system, perhaps due to model simplifications or inaccurate assumptions. The URC product, however, did benefit the system. Results show a reduction in the frequency of energy and operating reserve shortages when compared to the baseline model, particularly with high wind penetration, thereby indicating improved reliability. While there was a small price increase in non-shortage intervals due to procurement of URC, this was outweighed by the avoidance of high penalty prices incurred in shortage intervals; the overall average market clearing price was significantly reduced. The URC product also caused a small amount of fuel switching from coal to the more flexible natural gas, slightly reducing the system’s CO2 emissions. However, the more pronounced environmental benefit was the URC product’s ability to help the system absorb increased wind penetration while avoiding most of the corresponding increase in reliability problems.Item Open Access Beneficial Use Analysis of Alum Sludge from Drinking-water Treatment Plants for Portland Cement Manufacturing in Holly Hill, South Carolina(2018-04-26) Mims, AdamThe Portland Cement Manufacturing process has utilized a variety of natural and industrial byproduct materials to produce cement products at affordable costs. The global demand for cement is increasing and the effort to reduce emissions has placed emphasis on cement manufacturers to reduce their impacts. Emphasis on locating additional alternative raw materials and replacing decreasing industrial byproduct supplies become more important. A case study was conducted analyzing the industrial by product, alum sludge, from a drinking water treatment plant to assess its feasibility for cement production in South Carolina. The sludge was chemically analyzed and trialed as a raw material feed. A cost benefit analysis reviewed the cost savings between waste disposal and beneficial use as well as an environmental review of CO2 impacts from transportation and mining activities. The sludge is promising as a replacement and further trials and analysis will be needed to confirm its viability.Item Open Access Benefits of Energy Efficiency Standards: The Case of Residential Refrigerators(2021-04-29) Jain, Abhishek SanjayAn integral part of the modern American household, refrigerators are ubiquitous. Characterized by their constant load profile, refrigerators account for a substantial part of residential energy demand. Improving energy efficiency standards for refrigerators can offer a sizeable demand reduction and therefore be a pivotal part of climate change mitigation strategy. This study quantifies the benefits of implementing energy efficiency standards for residential refrigerators by considering three policy scenarios. An in-house Monte-Carlo model is developed to replicate important considerations in the rulemaking process through which the Department of Energy (DOE) sets the conservation standards. Our results indicate that the existing standards for refrigerators can realize savings equal to the electricity consumption of about 400,000 average U.S. homes by 2025. While these savings are critical, the benefits of this conservation standard are inequitable. Our study provides insights into how the benefits are realized across all the consumers in the country and provides recommendations for improving the rulemaking process.Item Open Access Bridging the Retail-Wholesale Divide In Electricity Markets: The Economics of Distributed Energy Resources(2015-04-24) Avent, Clayton; Chow, Dan; Lloyd, Matt; Seidenfeld, Josh; Tomovich, UroshIncreasing penetration of distributed energy resources (DERs) impacts electric grid operations and utility revenue requirements. Existing retail rate tariffs for commercial customers do not align with utilities’ wholesale market purchases of energy, ancillary services, and capacity guarantees, nor do they efficiently convey resource scarcity to customers to alter their consumption and DER deployment decisions. This report seeks to understand the effects that real time pricing has on electricity costs and incentives for DER deployment for small commercial building owners. Our analysis uses historical load data from multiple commercial building types throughout New Jersey to (i) evaluate the relationship between locational marginal prices (LMPs) and consumptive patterns, and (ii) explore the potential benefit of new electrical rate structures with increased granularity in the temporal and geographic dimensions. This assessment of potential savings for customers and utilities can be used to inform future rate design. Our key findings are as follows: (1) retail rates based on LMPs can benefit both distribution utilities and their customers; (2) any new rate introduced must be optional, as varying load attributes at specific sites result in very different experiences under these rates (i.e., almost half of subject sites are worse off); (3) utilities can reduce risk by implementing a retail rate with a real-time price signal.Item Open Access Challenges and Opportunities for a Clean Energy Future: A Case Study in the Carolinas(2022-04-22) Hooks, Mandy; Chen, Stefan; Bechler, Scott; Ma, YiyanIn the 2020 Integrated Resource Plans of Duke Energy Progress and Duke Energy Carolinas, the utility established a goal of reaching 70% greenhouse gas emissions reductions from 2005 levels by 2030 and carbon neutrality by 2050. In this study, we aim to take an objective view of the IRP’s assumptions and findings. We defined a base case for 2020, a business-as-usual pathway for 2035, and a decarbonization pathway for 2035. We then ran these pathways through a unit commitment model developed by the team at GRACE, a team of experts specializing in electric power systems optimization, to simulate a year of operations at Duke Energy. We examine which pathways can achieve 70% greenhouse gas emissions reductions and compare them in terms of emissions and costs. The goal is to objectively determine the assumptions and components of a pathway that achieves Duke Energy’s goals.Item Open Access China’s Involvement in Hydropower Development and its Implications for the Mekong Region: Case Studies of Two Projects in Laos(2012-04-26) Lee, Yi-YingThe rapid expansion of China’s involvement in hydropower development in the Mekong region has led to growing global concern over its dam building practices. While dam construction certainly has many beneficial aspects for the Mekong countries, it also poses major threats to the ecological system and to the livelihoods of the local communities. This masters project presents a literature review of negative impacts of large hydropower dams in the region and examines the ways in which current project development practices, and in particular the approaches taken by Chinese state-owned companies and financiers, contribute to the continuation of these negative effects. With a focus on Laos, two case studies are presented and examined using the Hydropower Sustainability Assessment Protocol (HSAP). Based on these case studies, the major impediments to reducing the negative environmental and socio-economic impacts of Chinese investments in hydropower projects in the Mekong region and in Laos specifically are identified, along with possible ways in which the World Wildlife Fund and other non-governmental organization can act to weaken these impediments.Item Open Access Coal-fired Power Plants with Flexible Amine-based CCS and Co-located Wind Power: Environmental, Economic and Reliability Outcomes(2016) Bandyopadhyay, RubenkaCarbon Capture and Storage (CCS) technologies provide a means to significantly reduce carbon emissions from the existing fleet of fossil-fired plants, and hence can facilitate a gradual transition from conventional to more sustainable sources of electric power. This is especially relevant for coal plants that have a CO2 emission rate that is roughly two times higher than that of natural gas plants. Of the different kinds of CCS technology available, post-combustion amine based CCS is the best developed and hence more suitable for retrofitting an existing coal plant. The high costs from operating CCS could be reduced by enabling flexible operation through amine storage or allowing partial capture of CO2 during high electricity prices. This flexibility is also found to improve the power plant’s ramp capability, enabling it to offset the intermittency of renewable power sources. This thesis proposes a solution to problems associated with two promising technologies for decarbonizing the electric power system: the high costs of the energy penalty of CCS, and the intermittency and non-dispatchability of wind power. It explores the economic and technical feasibility of a hybrid system consisting of a coal plant retrofitted with a post-combustion-amine based CCS system equipped with the option to perform partial capture or amine storage, and a co-located wind farm. A techno-economic assessment of the performance of the hybrid system is carried out both from the perspective of the stakeholders (utility owners, investors, etc.) as well as that of the power system operator.
In order to perform the assessment from the perspective of the facility owners (e.g., electric power utilities, independent power producers), an optimal design and operating strategy of the hybrid system is determined for both the amine storage and partial capture configurations. A linear optimization model is developed to determine the optimal component sizes for the hybrid system and capture rates while meeting constraints on annual average emission targets of CO2, and variability of the combined power output. Results indicate that there are economic benefits of flexible operation relative to conventional CCS, and demonstrate that the hybrid system could operate as an energy storage system: providing an effective pathway for wind power integration as well as a mechanism to mute the variability of intermittent wind power.
In order to assess the performance of the hybrid system from the perspective of the system operator, a modified Unit Commitment/ Economic Dispatch model is built to consider and represent the techno-economic aspects of operation of the hybrid system within a power grid. The hybrid system is found to be effective in helping the power system meet an average CO2 emissions limit equivalent to the CO2 emission rate of a state-of-the-art natural gas plant, and to reduce power system operation costs and number of instances and magnitude of energy and reserve scarcity.
Item Open Access Comparing estimates of SO2 and NOx emissions inventories for the U.S. and China: exploring the reasons for discrepancies between EDGAR and ECLIPSE(2017-04-28) Xu, Kaifeng; Sraha, Clementine; Liu, MingyuhuiThe EDGAR and ECLIPSE datasets contain estimates of past, current, and future emissions of greenhouse gases and other air pollutants, at the global, regional and national scales. These datasets are each a direct output of two models. This project compares the estimates of Nitrogen oxides (NOx) and Sulfur dioxide (SO2) for years 2000, 2005 and 2010 reported by ECLIPSE and EDGAR for the United States and China in order to examine the underlying assumptions and modeling structures and understand the sources of any differences between the two datasets. Results show that while global estimates from the two datasets are similar, there are noticeable discrepancies at the national level. These differences are due to the different ways each productive sector of the economy is grouped in order to estimate emissions, the different sources of information used to compile the datasets, and different underlying assumptions of each dataset. This study finds that the transportation sector is the driver of significant differences in estimates of both global and national NOx emissions and energy sector data at the regional level.