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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Next Generation Renewables and, Separately, Energy System Transformation, and Related Topics (CRADA CRD-14-557 Final Report)

The Joint Institute for Strategic Energy Analysis (JISEA, an institute within NREL) will support the design, development, delivery and dissemination of two (2) informational whitepapers, identified as Task 1 and Task 2, respectively: Next Generation Renewables and Energy Systems Integration. Note: multiple abstracts with each of 10 modifications.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2018

Optimal subhourly electricity resource dispatch under multiple price signals with high renewable generation availability

This article proposes a system-wide optimal resource dispatch strategy that enables a shift from a primarily energy cost-based approach, to a strategy using simultaneous price signals for energy, power and ramping behavior. A formal method to compute the optimal sub-hourly power trajectory is derived for a system when the price of energy and ramping are both significant. Optimal control functions are obtained in both time and frequency domains, and a discrete-time solution suitable for periodic feedback control systems is presented. The method is applied to North America Western Interconnection for the planning year 2024, and it is shown that an optimal dispatch strategy that simultaneously considers both the cost of energy and the cost of ramping leads to significant cost savings in systems with high levels of renewable generation: the savings exceed 25% of the total system operating cost for a 50% renewables scenario.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2024

Robust VAR Capability Curve of DER with Uncertain Renewable Generation

Active distribution system with high penetration of inverter based distributed energy resources(DER), can be utilized for var-related ancillary services at the transmission side interface. In order to utilize the DER flexibility, transmission system operator must be presented the aggregated DER flexibility of distribution system. However, the uncertainty in renewable generation, questions the credibility of aggregated capability curve in practice. In this paper, we incorporate the uncertainty into aggregation process to develop capability curve while preserving the real physics (unbalance and lossy nature) of distribution system. The Resulting capability curve with the associated probability can be harnessed by the TSO for decision making for both planning and operation.

Kar, Aditya Shankar↗
DOE OSTI2019

Interconnection Requirements for Renewable Generation and Energy Storage in Island Systems: Puerto Rico Example: Preprint

On September 20, 2017, Hurricane Maria made landfall in Puerto Rico, incapacitating the central power system and leaving the entire island without power. To ensure the long-term recovery of Puerto Rico's electric power grid in the most secure and resilient way, the U.S. Department of Energy funded research to develop recommendations for a cohesive new framework of interconnection standards for utility-scale renewable electrical generation and energy storage that ensure cross-technology compatibility and enable high deployment levels without compromising grid reliably, safety, or security. This paper provides a summary of work conducted by the National Renewable Energy Laboratory to analyze and address many shortcomings and areas of improvement to help the Puerto Rico Electric Power Authority (PREPA) establish minimum technical requirements for interconnecting single-technology and hybrid renewable generation because of their importance for PREPA system security and impacts on future integrated resource planning scenarios. Results and findings presented in this paper are important for any island power system.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2016

Power Generation for River and Tidal Generators

Renewable energy sources are the second largest contributor to global electricity production, after fossil fuels. The integration of renewable energy continued to grow in 2014 against a backdrop of increasing global energy consumption and a dramatic decline in oil prices during the second half of the year. As renewable generation has become less expensive during recent decades, and it becomes more accepted by the global population, the focus on renewable generation has expanded from primarily wind and solar to include new types with promising future applications, such as hydropower generation, including river and tidal generation. Today, hydropower is considered one of the most important renewable energy sources. In river and tidal generation, the input resource flow is slower but also steadier than it is in wind or solar generation, yet the level of water turbulent flow may vary from one place to another. This report focuses on hydrokinetic power conversion.

16 TIDAL AND WAVE POWER↗
DOE OSTI2014

Evolution of Wholesale Electricity Market Design with Increasing Levels of Renewable Generation

Variable generation such as wind and photovoltaic solar power has increased substantially in recent years. Variable generation has unique characteristics compared to the traditional technologies that supply energy in the wholesale electricity markets. These characteristics create unique challenges in planning and operating the power system, and they can also influence the performance and outcomes from electricity markets. This report focuses on two particular issues related to market design: revenue sufficiency for long-term reliability and incentivizing flexibility in short-term operations. The report provides an overview of current design and some designs that have been proposed by industry or researchers.

14 SOLAR ENERGY↗
DOE OSTI2022

Synchronization in electric power networks with inherent heterogeneity up to 100% inverter-based renewable generation

The synchronized operation of power generators is the foundation of electric power network stability and a key to the prevention of undesired power outages and blackouts. Here, we derive the conditions that guarantee synchronization in power networks with inherent generator heterogeneity when subjected to small perturbations, and perform a parametric sensitivity analysis to understand synchronization with varied types of generators. As inverter-based resources, which are the primary interfacing technology for many renewable sources of energy, have supplanted synchronous generators in ever growing numbers, the center of attention on associated integration challenges have resided primarily on the role of declining system inertia. Our results instead highlight the critical role of generator damping in achieving a stable state of synchronization. Additionally, we report the feasibility of operating interconnected electric grids with up to 100% power contribution from inverter-based renewable generation technologies. Our study has important implications as it sets the basis for the development of advanced control architectures and grid optimization methods that ensure synchronization and further pave the path towards the decarbonization of the electric power sector.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2024

Evolving Competitive Markets in SAPP: Leveraging Competitive Wholesale Electricity Markets to Drive Renewable Generation Capacity in the Southern African Power Pool (SAPP)

The SADC region has significant natural resource potential to increase renewable energy generation, improve electricity reliability, and support economic development. This research finds an apparent lack of confidence from electricity infrastructure investors in SAPP wholesale electricity markets, which increases risk perception and lowers the likelihood of capital deployment. With respect to free market fundamentals, competitive market obstacles and renewable energy development obstacles are characterized. Stakeholders identified the top obstacles to well-functioning competitive markets as insufficient transmission infrastructure for interconnection and regional movement of electricity, dominance of national single-buyer markets, and lack of or weak nation-state regulatory frameworks. Stakeholders prioritized the top three obstacles for renewable energy development as a lack of viable commercial arrangements for variable renewable energy (VRE) balancing, lack of functional and consistent nation-level regulations, and higher project costs related to reliance on imported equipment. With respect to potential solution options, stakeholders prioritized the development of new cost allocation and finance methods to facilitate new transmission expansion, training to educate new or potential new market entrants on SAPP processes, as well as modeling and analysis of regional SAPP participation benefits disaggregated to the nation-state level. From these perspectives, this research identified strategy options for consideration including transitioning SAPP to a regional transmission operator (RTO) for operation and planning of cross-border transmission facilities and market administration, shifting operations of SAPP member transmission systems to Independent System Operators (ISOs), establishing a regional regulatory authority and enhancing market data transparency. Implementing these reforms is expected to be challenging, but not insurmountable, given the domestic political, legal, and jurisdictional complexities of the SADC region.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2018

Production of Synthetic Natural Gas From Carbon Dioxide and Renewably Generated Hydrogen: A Techno-Economic Analysis of a Power-to-Gas Strategy

Power-to-gas to energy systems are of increasing interest for low carbon fuels production and as a low-cost grid-balancing solution for renewables penetration. However, such gas generation systems are typically focused on hydrogen production, which has compatibility issues with the existing natural gas pipeline infrastructures. This study presents a power-to-synthetic natural gas (SNG) plant design and a techno-economic analysis of its performance for producing SNG by reacting renewably generated hydrogen from low-temperature electrolysis with captured carbon dioxide. The study presents a 'bulk' methanation process that is unique due to the high concentration of carbon oxides and hydrogen. Carbon dioxide, as the only carbon feedstock, has much different reaction characteristics than carbon monoxide. Thermodynamic and kinetic considerations of the methanation reaction are explored to design a system of multistaged reactors for the conversion of hydrogen and carbon dioxide to SNG. Heat recuperation from the methanation reaction is accomplished using organic Rankine cycle (ORC) units to generate electricity. The product SNG has a Wobbe index of 47.5?MJ/m3 and the overall plant efficiency (H2/CO2 to SNG) is shown to be 78.1% LHV (83.2% HHV). The nominal production cost for SNG is estimated at 132 $/MWh (38.8 $/MMBTU) with 3 $/kg hydrogen and a 65% capacity factor. At U.S. DOE target hydrogen production costs (2.2 $/kg), SNG cost is estimated to be as low as 97.6 $/MWh (28.6 $/MMBtu or 1.46 $/kgSNG).

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2015

Renewable Generation Effect on Net Regional Energy Interchange: Preprint

Using production-cost model (PLEXOS), we simulate the Western Interchange (WECC) at several levels of the yearly renewable energy (RE) generation, between 13% and 40% of the total load for the year. We look at the overall energy exchange between a region and the rest of the system (net interchange, NI), and find it useful to examine separately (i) (time-)variable and (ii) year-average components of the NI. Both contribute to inter-regional energy exchange, and are affected by wind and PV generation in the system. We find that net load variability (in relatively large portions of WECC) is the leading factor affecting the variable component of inter-regional energy exchange, and the effect is quantifiable: higher regional net load correlation with the rest of the WECC lowers net interchange variability. Further, as the power mix significantly varies between WECC regions, effects of ‘flexibility import’ (regions ‘borrow’ ramping capability) are also observed.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2022

A reforecasting-based dynamic reserve estimation for variable renewable generation and demand uncertainty

The installed capacity of renewables-based energy sources has been increasing in traditional power systems. In order to accommodate the increased variability and uncertainty associated with the deeper penetration of renewable sources like solar and wind, adjusted amounts of dynamic reserve are needed. Although probabilistic dynamic reserve estimation methods have been previously developed, most of them consider the uncertainty to be represented by parametric density functions that tend to perform poorly under extreme events and, moreover, neglect uncertainty introduced by the forecasting model itself. Toward addressing these limitations, this work presents, for the first time, a dynamic reserve estimation method for flexibility that incorporates nonparametric density estimation and a machine learning based reforecasting to provide a day-ahead prediction of the mean and spread of uncertainty around the base forecast. The prediction is, in turn, used to estimate the up and down reserve relative to the base forecast. Here, the present method takes various endogenous and exogenous features, including the calendar variables, as input to estimate the day-ahead reserve. Using a combination of reforecasting and dynamic reserve estimation techniques, the method is shown to adjust better to the dynamic nature of reserve requirements providing only what is needed to accommodate the expected deviations. Considering California Independent System Operator (CAISO) solar, wind and load data over an 18 month period, up to 67% reduction in the amount of reserve capacity needed for a one day reserve and reserve penalty for solar uncertainty is demonstrated. Additionally, the risk of reserve insufficiency in meeting the net demand is reduced by 20% with the proposed method.

14 SOLAR ENERGY↗
DOE OSTI2016

Integrating Renewable Generation into Grid Operations: Four International Experiences

International experiences with power sector restructuring and the resultant impacts on bulk power grid operations and planning may provide insight into policy questions for the evolving United States power grid as resource mixes are changing in response to fuel prices, an aging generation fleet and to meet climate goals. Australia, Germany, Japan and the UK were selected to represent a range in the level and attributes of electricity industry liberalization in order to draw comparisons across a variety of regions in the United States such as California, ERCOT, the Southwest Power Pool and the Southeast Reliability Region. The study draws conclusions through a literature review of the four case study countries with regards to the changing resource mix and the electricity industry sector structure and their impact on grid operations and planning. This paper derives lessons learned and synthesizes implications for the United States based on answers to the above questions and the challenges faced by the four selected countries. Each country was examined to determine the challenges to their bulk power sector based on their changing resource mix, market structure, policies driving the changing resource mix, and policies driving restructuring. Each countries’ approach to solving those changes was examined, as well as how each country’s market structure either exacerbated or mitigated the approaches to solving the challenges to their bulk power grid operations and planning. All countries’ policies encourage renewable energy generation. One significant finding included the low- to zero-marginal cost of intermittent renewables and its potential negative impact on long-term resource adequacy. No dominant solution has emerged although a capacity market was introduced in the UK and is being contemplated in Japan. Germany has proposed the Energy Market 2.0 to encourage flexible generation investment. The grid operator in Australia proposed several approaches to maintaining synchronous generation. Interconnections to other regions provides added opportunities for balancing that would not be available otherwise, and at this point, has allowed for integration of renewables.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2023

Flexibility Requirements for Energy Systems with Renewable Generation under Forecast Uncertainties

Energy systems with high fractions of renewable energy-based resources require adequate assets providing flexibility in electricity usage to maximize the benefits of renewable energy. In this paper, we provide an analytical approach to estimate the flexibility requirements of such energy systems, with forecast uncertainties in both demand and generation. Our analytical results show that even with forecast errors, the expected system operating cost decreases with an increase in the amount of flexibility capacity -- however, there is an inflection point, beyond which addition of further flexibility capacity does not reduce expected system cost any further. Additionally, an enumeration-based approach is presented to estimate the maximum flexibility capacity needed to optimize the operating cost. Numerical experiments conducted on a network-abstracted modified IEEE 30-bus system are used for empirical validation and gaining additional insights on the effect of prosumers' willingness to offer flexibility on the dispatch performance.

Bhattacharya, Saptarshi↗
DOE OSTI2012

Decision-Support Software for Grid Operators: Transmission Topology Control for Infrastructure Resilience to the Integration of Renewable Generation

GENI Project: The CRA team is developing control technology to help grid operators more actively manage power flows and integrate renewables by optimally turning on and off entire power lines in coordination with traditional control of generation and load resources. The control technology being developed would provide grid operators with tools to help manage transmission congestion by identifying the facilities whose on/off status must change to lower generation costs, increase utilization of renewable resources and improve system reliability. The technology is based on fast optimization algorithms for the near to real-time change in the on/off status of transmission facilities and their software implementation.

ARPA-E↗
DOE OSTI2025

Impact Analysis of Utility-Scale Energy Storage on the ERCOT Grid in Reducing Renewable Generation Curtailments and Emissions

This paper explores the solutions for minimizing renewable energy (RE) curtailment in the Texas Electric Reliability Council of Texas (ERCOT) grid. By utilizing current and future planning data from ERCOT and the System Advisor Model from the National Renewable Energy Laboratory, we examine how future renewable energy (RE) initiatives, combined with utility-scale energy storage, can reduce CO2 emissions while reshaping Texas’s energy mix. The study projects the energy landscape from 2023 to 2033, considering the planned phase-out of fossil fuel plants and the integration of new wind/solar projects. By comparing emissions under different load scenarios, with and without storage, we demonstrate storage’s role in optimizing RE utilization. The findings of this paper provide actionable guidance for energy stakeholders, underscoring the need to expand wind and solar projects with strategic storage solutions to maximize Texas's RE capacity and substantially reduce CO2 emissions.

14 SOLAR ENERGY↗
DOE OSTI2025

Resilient Distributed Frequency Regulation of Renewable Generators under Communication Interruptions

Modern power systems (MPSs) face significant challenges due to the high penetration of renewable energy sources (RESs) and new types of loads such as electric vehicles (EVs). Traditional load frequency control (LFC) methods struggle with the intermittent, stochastic nature of RESs, the near-zero inertia of power-electronics-based generators, and the mobility of controllable loads and battery systems. This paper introduces a novel resilient distributed frequency regulation method to address these issues. The proposed method employs a state space model to represent the dynamic behavior of participating power sources while accounting for stochastic switching processes to model structural and parameter variations caused by disruptions such as generator connection/disconnection, communication interruptions, and physical faults. By integrating these dynamic and stochastic components, the method treats power grids as a comprehensive stochastic hybrid system. Our method enhances conventional frequency control by incorporating local stability control, neighborhood control decoupling, and coordination feedback. Theoretical analyses establish the stability, convergence, and resilience of the proposed method, and its effectiveness is validated through case studies.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2021

STOCHASTIC OPTIMAL POWER FLOW FOR REAL-TIME MANAGEMENT OF DISTRIBUTED RENEWABLE GENERATION AND DEMAND RESPONSE (Final Report)

To meet the grand challenge of a sustainable energy future, there has been a surge of interest in renewable energy. Today, the uncertainty associated with renewable resources is handled by using operating reserves. The high penetration of renewable resources, however, introduces difficult-to-control dynamics and challenges for power system operation. Decision support tools are necessary at the bulk system operational level to recognize and efficiently utilize renewable resources and distributed demand response products in concert with traditional grid resources. It is envisaged that responsive load can potentially have very significant cost advantages over either spinning or non-spinning ramping reserve. Critical decisions are made during hour(s)-ahead and real-time power system operation regarding the commitment and dispatch of generators to ensure power delivery is both reliable and economic. These decisions are typically made by a security constrained optimal flow, which determines future generator commitments, dispatches, and ensures adequate reserves are available in the event of a contingency (unexpected outage) or if future system conditions deviate from forecasts. However, security has been always based on a pre-specified subset of contingency constraints whose enforcement does not guarantee security under all possible future possibilities while also giving little or no weight to the likelihood of each contingent event or the severity of its consequences. Existing tools, which are based exclusively on deterministic optimization models, do not yield optimal operational decisions to address these new challenges, in terms of both reliability and cost-effectiveness. This project has focused on developing a stochastic optimal power flow (SOPF) framework, which integrates renewable resource uncertainty, load uncertainty, distributed storage (DS), demand response (DR) products, in a holistic manner to address the uncertainty associated with ever-increasing renewable resources, along with the inclusion of distributed demand response products in future power systems. A proof-of-concept problem was created using the Pennsylvania-Jersey-Maryland (PJM) power system network. Synthetic wind generation was added to the system to simulate 50% wind penetration. A 1-hour test of SOPF operation indicated more than 6% operational cost savings. The project continued by adding the Midwestern Independent System Operator (MISO) as a partner, with focus shifting from SOPF to Stochastic Look-Ahead Unit Commitment (SLAC). Unlike PJM, MISO is faced with significant renewable energy resources within its footprint and is challenged with substantial uncertainty in its operations. The SLAC distinguishes itself from existing tools that operators use. At best, today’s tools solve two to three cases independently, where one or two system parameters, such as forecasted load level (e.g., a low, base, and high forecast), are varied and the resulting scenarios are analyzed independently. The stochastic-based optimization of SLAC leverages statistical information from an ensemble of potential operational scenarios and their respective likelihood. The SLAC output can be translated into valuable information to the operator such as suggested commitments, optimal scheduling and dispatch of resources, reserve requirements at both locational and zonal resolutions, ramping availability and requirements, availability of demand response including operational guidance concerning the near-term and real-time coordination between distributed energy resources, and utilization of distributed storage resources. The developed SOPF/SLAC tool, a stand-alone tool compatible with existing EMSs, will provide system operators with unprecedented visibility, flexibility and predictability to these resources and operational guidance concerning the real-time coordination between DERs and DR/DS products. The game changing and practical impact of this disruptive technology will be dramatic and will usher in a new era in the electric power industry, wherein green energy concepts are fully embraced, and electric power costs are lowered throughout the nation.

42 ENGINEERING↗
DOE OSTI2024

Modeling the impact of extreme summer drought on conventional and renewable generation capacity: Methods and a case study on the Eastern U.S. power system

Across recent years, there has been a growing prevalence of extreme weather events throughout the United States, posing significant challenges to the reliable and resilient operation of power systems. Specifically, summer droughts threaten to severely reduce available generation capacity to meet regional electricity demand, potentially leading to power outages. This underscores the importance of accurate resource adequacy (RA) assessment to ensure the reliable operation of the nation’s energy infrastructure. Accurately evaluating the usable capacity of regional generation fleets is a challenging undertaking due to the intricate interactions between power systems and hydro-climatic systems. Here, this paper proposes a systematic and analytical framework to evaluate the impacts of extreme summer drought events on the available capacity of various generating technologies, incorporating both meteorological and hydrologic factors. The framework provides detailed plant-level capacity derating models for hydroelectric, thermoelectric, and renewable power plants, facilitating evaluations with high temporal and spatial resolution. The application of the proposed impact assessment framework to the 2025 generation fleet of the real-world power system within the PJM and SERC regions of the United States yields insightful results. By analyzing the daily usable capacity of 6,055 at-risk generators across the study region, it shows that the summer capacity deration is most significant for hydroelectric and once-through thermal power plants, followed by recirculating thermal power plants and combustion turbines. In the event of the recurrence of the 2007 southeastern summer drought event in the near future, the generation fleet could experience a substantial reduction in available capacity, estimated at approximately 8.5 GW, compared to typical summer conditions. The sensitivity analysis reveals that the usable capacity of the generation fleet would suffer an even more significant decrease under conditions of increasingly severe summer droughts. The proposed approach and the findings of this study provide valuable methodologies and insights, empowering stakeholders to bolster the resilience of power systems against the potentially devastating effects of future extreme drought events.

24 POWER TRANSMISSION AND DISTRIBUTION↗