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At least 523 records · Page 29

Design of a Compact Dry Cooler With an Aluminum Heat Exchanger Core for a Supercritical CO2 Power Cycle Is Evaluated for a Concentrating Solar Power Application

Abstract As the supercritical CO2 power cycle develops and the component technologies mature, there is still a need to reduce the associated capital and operating costs to maintain a competitive levelized cost of electricity (LCOE) in order to enter the market. When considering concentrating solar power (CSP) coupled with an sCO2 power block and sensible thermal storage, the technology presents a clean source for utility-scale power generation to support baseload or peak-load electrical demand. However, the LCOE of the technology is still considered higher than the competing technologies and should be reduced to better compete in the market; 2030 targets for dispatchable solar plants are 5¢/kWh for baseload CSP and 10¢/kWh for peaker plants, as set by the United States Department of Energy. In response to this need, this study is targeting improvements in the power cycle precooler to reduce power block contribution to LCOE. This study considers a dry cooler, as CSP plants are sensitive to water consumption because many installations are slated for remote or arid locations where solar irradiance is very high, but water is scarce. Furthermore, the power block footprint for an sCO2 system is quite compact, especially as compared to a steam cycle. Therefore, there is interest in installing a more compact dry cooler that is proportional to the reduced footprint sCO2 power block, while conventional dry coolers are an order of magnitude larger. The competing goals of size, performance, and cost were considered in this study to develop a compact dry cooler that can easily be packaged with the power block, significantly reducing the installation and transport cost compared to the current state of the art, while maintaining or improving upon the heat transfer performance and impact on plant LCOE. This paper details the high-level findings of a large dry cooler sensitivity study for design point selection, design of the compact dry cooler, expected year-round performance for the dry cooler and the power cycle, and the predicted LCOE for a 30-year plant life. It was found that an aluminum heat exchanger core can be suitably designed to meet the pressure and temperature requirements for a precooler in an sCO2 recompression Brayton cycle. The dry cooler assembly was found to have improved heat transfer performance, allowing for increased cycle efficiencies and a reduced plant LCOE. When coupled with a centrifugal blower and compact transition duct, the dry cooler assembly was able to reduce the installation footprint by over 50%.

14 SOLAR ENERGY↗

Flexibility Options: A Proposed ISO Product for Managing Energy Imbalance Risk

As the electricity generated by variable resources grows, system operators and variable resources have to manage challenging imbalances between forward and real-time markets. The Flexibility Auction is a novel approach for managing imbalances as it will allow resources with imbalance risk to hedge their production by buying flexibility options. The flexibility options are offered by grid-connected resources that can provide physical flexibility. This presentation provides an overview of the participants in the auction, the definition of flexibility options, and settlements.

27 ARPA - Advanced Research Projects Agency-Energy↗

Transmission Value in 2023: Market Data Shows the Value of Transmission Remained High in Certain Locations Despite Overall Low Wholesale Electricity Prices

In 2023 additional electricity transmission would have provided the most value for links that crossed between grid interconnection regions in the United States (the Western Interconnection, the Eastern Interconnection, the Texas Interconnection) or crossed between system operator regions within the same interconnection. Many multi-interconnection or multi-region links had values of greater than $\$20$/MWh, or up to $\$175$ million/yr per 1 GW expanded transmission (subject to limits to the depth of the market at each side of the link). In contrast, many links within regions, or between regions in the northeast, had relatively low values in 2023, following the overall decline in wholesale electricity prices in 2023 compared with 2021-2022. The most valuable link in 2023, at $\$61$ /MWh, was between Texas and the Southwest. Multiple events in 2023 (high natural gas prices in the western U.S., and high summer temperatures in Texas and the Southwest) were observed to have driven this high value. Of particular note, high prices in Texas occurred at a largely distinct set of hours from high prices in the Southwest, helping to drive up the value of transmission in total and demonstrating significant value to both regions. This example demonstrates the unique value of transmission (compared to other solutions, such as building local generation resources) in delivering benefits to multiple regions given its ability to connect areas of the country that inevitably face differing circumstances.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

RePED 250: Manufacturing and Market Analysis of High-Temperature Alternators

The novel repetitive pulsed electric drill 250 (RePED 250) has the potential to greatly lower the costs and drilling times of geothermal projects. This tool discharges electric pulses through hard rock formations, shattering the rock in tension and allowing it to be quickly removed. One hurdle in bringing this technology to market is the RePED 250 downhole alternator. This component is essential for supplying power to the electronic drilling tool. There are currently no downhole tools on the market that meet the RePED 250 alternator's high temperature and power requirements. This report focuses on the path to commercialization for this novel alternator technology being developed as part of the RePED 250 project. One aim of this work is to identify the geothermal market size for the RePED 250 alternator, as well as other potential markets for this technology outside of geothermal. The geothermal market is very small, with only approximately 13 wells drilled in the United States each year. The worldwide market is several times this size and growing each year. The ability of the RePED 250 technology to drastically reduce the cost of geothermal projects may also lead to an increase in this market size. Technology developed for the high-temperature, high-power RePED 250 alternator can also be used to create high-temperature and high-power motors. These motors and alternators will have potential applications in oil and gas drilling, a $300 billion dollar industry in the United States alone, as well as in more distant industries such as aircraft, weapon systems, space exploration, and electric vehicles. Other aspects of the RePED 250 alternator's path to commercialization are also analyzed, including the supply chain for production materials and potential manufacturing methods. The supply chain and manufacturing practices for low-temperature motors and alternators are well established and require relatively minor changes for the high-temperature and high-power RePED 250 alternator. Sourcing for high-temperature materials has been identified, as well as potential supply chain risks. These most notably include electrical steel and high-temperature samarium cobalt (SmCo) magnets. Overall, these risks are not expected to be significant at the likely manufacturing scale required for the RePED 250.

15 GEOTHERMAL ENERGY↗

Analysis of Electrical Grid Capacity in Major U.S. Metropolitan Areas for Urban Air Mobility

A wide range of challenges must be overcome to conduct Urban Air Mobility (UAM) operations at scale with electric vertical takeoff and landing aircraft as envisioned. This paper documents an analysis of one potential infrastructure challenge for UAM: available electrical grid power capacity. The success of UAM depends on the availability of electricity, which will be increasingly impacted by the proliferation of ground electric vehicles (EVs) over time. Under the worst-case assumption that each U.S. Metropolitan Statistical Area (MSA) can only access and utilize the electricity generated by power plants within its boundaries, it is estimated that the maximum number of UAM aircraft that can charge simultaneously in the 25 most populous MSAs will decrease by about 61% from about 129,000 in the year 2021 to about 51,000 in the year 2050, due to the projected increase in ground EVs. Also, it is estimated that the number of these MSAs that may lack any available electrical grid power capacity for UAM operations will increase from zero MSAs in 2021 to eleven MSAs in 2050—including three MSAs that prospective UAM operators have announced as target markets (Los Angeles, Miami, and Orlando)—unless electricity demand for other purposes is reduced.

electrical grid↗

Analysis of Electrical Grid Capacity in Major U.S. Metropolitan Areas for Urban Air Mobility

A wide range of challenges must be overcome to conduct Urban Air Mobility (UAM) operations at scale with electric vertical takeoff and landing aircraft as envisioned. This paper documents an analysis of one potential infrastructure challenge for UAM: available electrical grid power capacity. The success of UAM depends on the availability of electricity, which will be increasingly impacted by the proliferation of ground electric vehicles (EVs) over time. Under the worst-case assumption that each U.S. Metropolitan Statistical Area (MSA) can only access and utilize the electricity generated by power plants within its boundaries, it is estimated that the maximum number of UAM aircraft that can charge simultaneously in the 25 most populous MSAs will decrease by about 61% from about 129,000 in the year 2021 to about 51,000 in the year 2050, due to the projected increase in ground EVs. Also, it is estimated that the number of these MSAs that may lack any available electrical grid power capacity for UAM operations will increase from zero MSAs in 2021 to eleven MSAs in 2050—including three MSAs that prospective UAM operators have announced as target markets (Los Angeles, Miami, and Orlando)—unless electricity demand for other purposes is reduced.

electrical grid↗

Status and Trends in the U.S. Voluntary Power Market: 2024 Data

Voluntary renewable power, for this report, refers to renewable energy procurement by retail electricity customers above what is otherwise provided by load-serving entities. This report is part of an annual series of reports synthesizing trends in the U.S. voluntary renewable power market. In 2024, about 9.2 million retail electricity customers procured about 315 million megawatt-hours (MWh) of voluntary renewable power (Figure ES-1). Estimated voluntary renewable power market sales represented about 45% of renewable energy sales excluding large hydropower and about 8% of all U.S. retail electricity sales in 2024. Most of the remainder of U.S. renewable energy sales reflects renewable energy procured by load-serving entities to comply with state renewable energy mandates.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

Status and Trends in the U.S. Voluntary Power Market: 2023 Data

Voluntary green power, for this report, refers to renewable energy procurement by retail electricity customers above what is otherwise provided by load-serving entities. This report is part of an annual series of reports synthesizing trends in the U.S. voluntary green power market. In 2023, about 9.7 million retail electricity customers procured about 319 million megawatt-hours (MWh) of voluntary green power (Figure ES-1), representing a 17% increase over sales in 2022. Estimated voluntary green power market sales represented about 44% of non-hydropower renewable energy sales and about 8% of all U.S. retail electricity sales in 2023. Most of the remainder of U.S. renewable energy sales reflects renewable energy procured by load-serving entities to comply with state renewable energy mandates, also known as compliance-based procurement. The U.S. voluntary green power market is undergoing a clear shift toward long-term contracts, driven primarily by increasingly ambitious corporate renewable energy procurement targets.

2023↗

Zero Export Feeder Through Transactive Markets

This project is aimed at creating a transactive energy market to address the challenges faced by utility providers when increasing distributed energy resource (DER) adoption in their service area. One major challenge is mitigating export back to the grid during times of excess production. The transactive energy market operates at the distribution level and balances the supply and demand on the feeder, thus maintaining a zero-energy export at the primary feeder head. The market participants in this case are the residential customers on the feeder, who bid into the market. Building controls are then optimized based on the settled price. Market performance was demonstrated in this study by simulating different levels of DER penetration on a selected Pepco feeder. The feeder successfully achieved a zero export while providing cost-effective electricity to the participants, demonstrating that this market design can enable high DER penetration on existing feeders.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

plutus: An R package to calculate electricity investments and stranded assets from the Global Change Analysis Model (GCAM)

plutus is an R package that post-processes outputs from the Global Change Analysis Model (GCAM) to calculate the power sector capital investment costs and stranded asset costs associated with GCAM projections of electricity generation by technology. GCAM is a market equilibrium model used to examine the dynamics of the coupled human-Earth system and the response of this system to global change, including socioeconomics, technology, climate, and policy. GCAM tracks electricity generation by technology and vintage over 32 geopolitical regions throughout the lifetime of each generating technology. plutus extends GCAM functionality by (1) estimating the foregone economic value of prematurely retired power plants as a result of economic-induced retirements compared to scheduled lifetimes; and (2) estimating the new installations and capital investments driven by future changes in economic, energy, agriculture, and land-use systems in GCAM.

97 MATHEMATICS AND COMPUTING↗

The Role of Concentrating Solar-Thermal Technologies in a Decarbonized U.S. Grid

The National Renewable Energy Laboratory’s Solar Futures Study explores the roles solar energy technologies could play in the future U.S. energy markets under different scenarios. This report discusses the role of concentrating solar-thermal (CST) technologies in those future scenarios with an emphasis on concentrating solar-thermal power (CSP), which refers to converting thermal energy to electricity. The report begins with an overview of the CSP resource and market status. Next we discuss the results from the grid-scale capacity planning modeling under future scenarios considered in the Solar Futures Study, focusing on the results for CSP and presenting several sensitivity model results not discussed in the main report. We then discuss likely CST research and industry directions over the next decade. Finally we discuss three potential future markets for CST beyond electricity generation -- industrial process heat, solar fuels production, and electric thermal energy storage.

14 SOLAR ENERGY↗

Estimating Energy Market Schedules using Historical Price Data

The global climate crisis is expected to reshape the energy generation landscape in the coming decades. Increasing integration of non-dispatchable renewable energy resources into energy infrastructures and markets creates uncertainty as well as new opportunities for flexible energy systems. To conduct proper economic evaluation of flexible energy systems, such as integrated energy systems (IES), advancements in modelling of market interactions, such as bidding, is crucial. This work presents a shortcut algorithm which uses two mixed integer linear programs to compute dispatch schedules (e.g., hourly power production targets) that are constrained by the resource's bid information and characteristics (e.g., minimum up and down times) based on historical locational marginal price (LMP) data. The proposed algorithm is approximately 100 times faster and uses orders of magnitude less data than a full production cost model (PCM). We find the shortcut simulator recapitulates generator dispatch signals for the Prescient PCM with approximately 4% error for the RTS-GMLC test system.

electricity generation↗

Microreactor Applications in U.S. Markets: Evaluation of State-Level Legal, Regulatory, Economic and Technology Implications

This report provides an evaluation of state-level legal, regulatory, economic and technology implications for microreactor applications in U.S. markets. The initial focus is on Alaska (AK) and Wyoming (WY) energy markets serving location-specific energy needs for electricity and heat. A state-by-state evaluation of current carbon/carbon-related policies and nuclear policies is conducted to assess broader market applicability in states undergoing energy transitions.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

Acoustic Testing of the Joby Aviation Propeller in the National Full-Scale Aerodynamics Complex 40- by 80-Foot Wind Tunnel

The advanced air mobility sector has progressed in recent years with electric vertical take-Off and landing vehicles at the forefront. In response, the NASA Advanced Air Mobility Project has initiated the Advanced Air Mobility National Campaign to partner with industry to progress this emerging market. This resulted in NASA’s Revolutionary Vertical Lift Technology project to participate to progress research efforts for software tool validation for these advanced air mobility vehicle configurations. Noise has been identified as one of the main obstacles to succeeding in this emerging market for community acceptance. To further understand electric vertical take-Off and landing vehicle noise, an isolated Joby Aviation S4 propeller was tested in the National Full-Scale Aerodynamics Complex 40- by 80-Foot Wind Tunnel to aid in providing high quality performance, loads, and acoustic data. Details of test hardware and setup are described with a focus on acoustics, which includes facility, test model, microphone locations, and data acquisition system details. Additionally, the data processing techniques and completed test matrix for acoustic points are provided. To aid in identifying potential acoustic reflections, an acoustic reflection test was performed prior to the start of the test and highlighted the presence of reflections at every microphone location. Acoustic results are provided for various flight regimes for sweeps of blade pitch, RPM, flow angle, and wind speed. These results show an optimum RPM for a specific thrust level for noise, and further reductions in RPM can increase noise levels. This dataset will be used to evaluate and improve computational tools.

Aviation Propeller↗

Interregional Electricity Transmission in the United States: Realized Savings and Opportunities for Increased Value, 2014 to 2023

Interregional electricity trade in the United States reduces total energy costs, but falls short of maximizing the economic potential of existing transmission infrastructure. This analysis of thirty-two U.S. electricity system interfaces crossing grid or market seams finds an average achieved cost savings of at least $1,226 million per year. This positive impact is offset by an average annual cost of uneconomic interchange of $551 million. Additional value of at least $238 million per year could be enabled by increasing utilization. Notably, uneconomic flows and low utilization rates can persist even when the price spread between regions is large. These conclusions are derived from historical (2014–2023) data on the magnitude and direction of interregional price spreads, the magnitude and direction of net energy transfers, and how these variables coincide, but do not account for all system constraints. These findings motivate the development and deployment of solutions that improve interregional transmission operations, in parallel with robust transmission infrastructure planning. JEL Classification: Q40 Energy: General

Q40 Energy: General↗

Potential State Regulatory Pathways to Facilitate Low-Carbon Fuels

States and the federal government are increasingly engaged in the challenges around decarbonizing the electric grid. In particular, regulators, consumers, stakeholders, and utilities recognize the need to carefully consider the role natural gas will play in a decarbonized future. A variety of technology and policy options to reduce greenhouse gas emissions associated with natural gas use are available, including energy efficiency programs, demand reduction tools, strategic electrification, and strategies to reduce emissions from natural gas production, transportation, and consumption. Low-carbon fuels – mainly renewable natural gas (RNG) and clean hydrogen – are being considered an important component of decarbonization goals. RNG and hydrogen may be able to meaningfully reduce emissions from processes independent of geologic natural gas, displacing emissions of methane, a powerful greenhouse gas. Although RNG and hydrogen are not cost-competitive today with geologic natural gas and are smaller in scale and potential than other decarbonization options, they can be explored as potential critical tools to decarbonize sectors that are difficult to electrify or shift off of natural gas entirely, such as air travel, industrial processes, maritime transport, long-distance trucking, space heating on cold days, and railroads (Nadel, 2022). The role of this report is to provide informational context for state utility regulators to understand the impacts of and challenges associated with broader integration of low-carbon fuels, followed by examples of state regulatory actions taken to date to facilitate the development of low-carbon fuels. Setting clear guidance to calculate the environmental benefits of low-carbon fuels and continuing federal and state investments in research and development to reduce costs relative to fossil fuels will be important steps to take to signal the desire to grow the market for these fuels. State public utility commissions may play a key role in setting regulatory frameworks for low-carbon fuels and ensuring that ratepayer funds, if utilized, are done so to further the public interest. This report is intended to summarize decisions that states have made to date on low-carbon fuels. In the spirit of understanding the current market and sharing information, this report provides success stories, and lessons learned across states as regulators implement varying strategies to achieve decarbonization objectives while maintaining their focus on affordability, safety, and reliability of the energy system. The report begins with an introduction of the role of natural gas in the U.S. economy (Section I) and background information on natural gas use, decarbonization, and low-carbon fuels (Section II). Next, the report describes the current market by discussing the scale of current production, emissions intensity, resource potential, and costs of low-carbon fuels compared to geologic natural gas (Section III). Following these sections, the report describes four strategies states have employed to facilitate low-carbon fuels: opening exploratory dockets, approving voluntary tariffs for customers, approving interconnection tariffs for producers, and considering portfolio-wide procurement targets (Section IV). This section lists states that have taken actions in each category, citing utility filings, commission decisions, stakeholder comments, and other relevant sources. Finally, the report concludes with suggested questions regulators may wish to consider regarding low-carbon fuels, in the interest of preparing to make decisions in the future (Section V). These questions include: Are there existing regulatory or technical barriers to voluntary purchases of low-carbon fuels? Can customers work with utilities to procure low-carbon fuels; are producers able to interconnect projects without significant barriers to entry? Should the infrastructure and/or commodity costs of low-carbon fuels be socialized among all ratepayers, or borne solely by the large commercial and industrial (C&I) customers currently driving the market? Should regulated natural gas and/or electric utilities own and operate low-carbon fuel production? How should regulators consider the unique decarbonization potential of low-carbon fuels, particularly for hard-to-abate sectors, in decision-making? Is additional direction or clarity from state policymakers needed? What no-regrets approaches can help facilitate both near-term RNG development and long-term development of hydrogen and other zero-carbon fuels? We collectively wish to express our gratitude to the U.S. Department of Energy, Office of Fossil Energy and Carbon Management, for supporting this report and other technical assistance resources for state regulators on natural gas topics. State regulators operate under a variety of policy environments, and states have vastly different types of energy resources, infrastructure, and customers. While there is no optimal regulatory, policy, or technological solution that will be successful in every state, state regulators can benefit by exchanging lessons learned with their peers across the country. We look forward to continued engagement with our fellow commissioners, commission staff, NARUC, the U.S. Department of Energy, and other stakeholders to develop sound regulation in the public interest.

03 NATURAL GAS↗

The hidden value of large-rotor, tall-tower wind turbines in the United States

The significant upscaling of wind turbine size (nameplate capacity, rotor diameter, and tower height) has, to date, been driven primarily by a goal of minimizing the levelized cost of energy. But with wind’s levelized cost of energy now comparable with that of other generating resources, other design considerations besides cost-minimization have grown in importance—particularly as wind’s increasing market penetration begins to impose challenges on the electric grid. We find that taller towers and larger rotors (relative to nameplate capacity) can enhance the value of wind energy to the electricity system and provide other “hidden” benefits. Specifically, in regions where wind penetration has reached around 20%, we find a boost in wholesale market value of US$2–US$3/MWh. This is augmented by transmission, balancing, and financing benefits that sum to roughly US$2/MWh. The aggregate potential value enhancement of US$4–US$5/MWh is comparable with a 10%–15% reduction in levelized costs.

17 WIND ENERGY↗