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At least 1,045 records · Page 58

Simulating the Value of Concentrating Solar Power with Thermal Energy Storage in a Production Cost Model

Concentrating solar power (CSP) deployed with thermal energy storage (TES) provides a dispatchable source of renewable energy. The value of CSP with TES, as with other potential generation resources, needs to be established using traditional utility planning tools. Production cost models, which simulate the operation of grid, are often used to estimate the operational value of different generation mixes. CSP with TES has historically had limited analysis in commercial production simulations. This document describes the implementation of CSP with TES in a commercial production cost model. It also describes the simulation of grid operations with CSP in a test system consisting of two balancing areas located primarily in Colorado.

14 SOLAR ENERGY↗

Integrated Canada-U.S. Power Sector Modeling with the Regional Energy Deployment System (ReEDS)

The electric power system in North America is linked between the United States and Canada. Canada has historically been a net exporter of electricity to the United States. The extent to which this remains true will depend on the future evolution of power markets, technology deployment, and policies. To evaluate these and related questions, we modify the Regional Energy Deployment System (ReEDS) model to include an explicit representation of the grid-connected power system in Canada to the continental United States. ReEDS is unique among long-term capacity expansion models for its high spatial resolution and statistical treatment of the impact of variable renewable generation on capacity planning and dispatch. These unique traits are extended to new Canadian regions. We present example scenario results using the fully integrated Canada-U.S. version of ReEDS to demonstrate model capabilities. The newly developed, integrated Canada-U.S. ReEDS model can be used to analyze the dynamics of electricity transfers and other grid services between the two countries under different scenarios.

24 POWER TRANSMISSION AND DISTRIBUTION↗

A Survey of Recent Advances in Transmission Network Switching

Optimal Transmission Switching for electric power networks is a research topic of great interest for both researchers and electric power engineers. Transmission switching is commonly considered a corrective mechanism tool for overloaded networks; however in recent years it has been sought as a means to reduce power loss in the network. Ultimately the objective of this analysis is to provide smart tools for power and economic dispatch planning, allowing utilities and engineers to utilize existing infrastructure as a means of automatic control. The optimization problem is a complex multi-objective search including criteria such as system power loss, equality/non-equality constraints, islanding management, and radial topology configuration in the case of distribution networks. Many optimization methods have been adopted for the transmission switching problem in past years using various heuristic search algorithms. The scope of methodology extends from tried and true methods such as simulated annealing to more modern methods like neural network optimization. Solution benchmarks under consideration commonly include solution state accuracy, computational burden and solution time. The objective of this presentation is to provide a comprehensive account of development in transmission switching methodologies. Benchmarking and testing strategies will be discussed as well as application of the Transmission Expansion Planning Tool in finding transmission switching solutions. Limited Discrepancy Search (LOS) and Probe Discrepancy Search (PDS) Algorithms are compared with more classic optimization strategies, as seen in defining literature and publications in this research field.

24 POWER TRANSMISSION AND DISTRIBUTION↗

Innovative Application of Maintenance-Free Phase-Change Thermal Energy Storage for Dish-Engine Solar Power Generation

This final report summarizes the final results of the Phase II Innovative Application of Maintenance-Free Phase-Change Thermal Energy Storage for Dish-Engine Solar Power Generation project being performed by Infinia Corporation for the U.S. Department of Energy under contract DE-FC36-08GO18157 during the project period of September 1, 2009 - August 30, 2012. The primary objective of this project is to demonstrate the practicality of integrating thermal energy storage (TES) modules, using a suitable thermal salt phase-change material (PCM) as its medium, with a dish/Stirling engine; enabling the system to operate during cloud transients and to provide dispatchable power for 4 to 6 hours after sunset. A laboratory prototype designed to provide 3 kW-h of net electrical output was constructed and tested at Infinia's Ogden Headquarters. In the course of the testing, it was determined that the system's heat pipe network - used to transfer incoming heat from the solar receiver to both the Stirling generator heater head and to the phase change salt - did not perform to expectations. The heat pipes had limited capacity to deliver sufficient heat energy to the generator and salt mass while in a charging mode, which was highly dependent on the orientation of the device (vertical versus horizontal). In addition, the TES system was only able to extract about 30 to 40% of the expected amount of energy from the phase change salt once it was fully molten. However, the use of heat pipes to transfer heat energy to and from a thermal energy storage medium is a key technical innovation, and the project team feels that the limitations of the current device could be greatly improved with further development. A detailed study of manufacturing costs using the prototype TES module as a basis indicates that meeting DOE LCOE goals with this hardware requires significant efforts. Improvement can be made by implementing aggressive cost-down initiatives in design and materials, improving system performance by boosting efficiencies, and by refining cost estimates with vendor quotes in lieu of mass-based approaches. Although the prototype did not fully demonstrate performance and realize projected cost targets, the project team believes that these challenges can be overcome. The test data showed that the performance can be significantly improved by refining the heat pipe designs. However, the project objective for phase 3 is to design and test on sun the field ready systems, the project team feels that is necessary to further refine the prototype heat pipe design in the current prototype TES system before move on to field test units, Phase 3 continuation will not be pursued.

14 SOLAR ENERGY↗

Analysis of Benefits of an Energy Imbalance Market in the NWPP

The Northwest Power Pool (NWPP) Market Assessment Committee (MC) Initiative, which was officially launched on March 19, 2012, set out to explore a range of alternatives that could help the Balancing Authorities and scheduling utilities in the NWPP area address growing operational and commercial challenges affecting the regional power system. The MC formed an Analytical Team with technical representatives from each of the member Balancing Areas in the NWPP and with staff of Pacific Northwest National Laboratory (PNNL). This Analytical Team was instructed to conduct extensive studies of intra-hour operation of the NWPP system in the year 2020 and of the NWPP region with 14,671 MW of wind penetration. The effort utilized a sub-hourly production cost model (the PLEXOS® computer model) that inputs data from the Western Electricity Coordinating Council (WECC)-wide Production Cost Model (PCM) to evaluate potential production cost savings. The Analytical Team was given two general options to evaluate: •Energy Imbalance Market (EIM): establishment of an automated, organized NWPP area market for economically supplying energy imbalance within the hour. •Enhanced Market-Operational Tools (EMT) that might augment or replace an EIM. The Analytical The Analytical Team built on the WECC-wide PCM data from prior work done in the WECC and carried forward the evolution of the original WECC Transmission Expansion Planning Policy Committee (TEPPC) 2020 PC0 data base. A large number of modifications and improvements were made to this case and the data were subjected to extensive review by the team members to improve the model representation of the Northwest (NW). MC meetings that were open to the public were held for interested parties to review and provide input to the study. Results for the test, base, and sensitivity case studies performed by the MC Initiative Analytical Team indicate that there are a wide range of benefits that could be obtained from the operation of an EIM in the NWPP depending on what assumptions are made. The instructions from the MC were to determine a "minimum high confidence" range of potential benefits. The results for the Base Case indicate that the EIM benefits ranged from approximately $40 million to $70 million in annual savings from the operation of an EIM in the NWPP footprint. A number of additional relevant sensitivity cases were performed, including low and high water conditions, low and high natural gas prices, and various flex reserve requirements, resource operations, and amounts of resource capability held back during the preschedule period. Along with the results for the Base Case, the results for these studies yielded EIM benefits that clustered within the range of $70 to $80 million dollars per year with potential benefits ranging from approximately $125 million to as little as $17 million per year. Because the design and operation of an EIM could enable participating Balancing Authorities (BAs) to collectively lower the quantity of resources they must carry to meet within-hour balancing needs, a sensitivity case was also performed to analyze the impact that such reductions might have on the benefits from an EIM. The results for this sensitivity case indicate that such reductions could increase the benefits from the operation of an EIM in the NWPP into the range of approximately $130 million to $160 million per year. Also, a sensitivity case for a WECC-wide EIM was performed with the results indicating that the potential benefits to the NWPP could increase into the range of $197 million to $233 million per year. While there may be potential reliability benefits from the coordinated dispatch process underlying the operation of an EIM, reliability benefits from an EIM were out of the scope of this study. The EIM benefit analyses that were performed by the Analytical Team are provided in this report.

Power markets, NWPP, Energy Imbalance, EIM, Renewa↗

Dynamic Line Rating Oncor Electric Delivery Smart Grid Program

Electric transmission lines are the lifeline of the electric utility industry, delivering its product from source to consumer. This critical infrastructure is often constrained such that there is inadequate capacity on existing transmission lines to efficiently deliver the power to meet demand in certain areas or to transport energy from high-generation areas to high-consumption regions. When this happens, the cost of the energy rises; more costly sources of power are used to meet the demand or the system operates less reliably. These economic impacts are known as congestion, and they can amount to substantial dollars for any time frame of reference: hour, day or year. There are several solutions to the transmission constraint problem, including: construction of new generation, construction of new transmission facilities, rebuilding and reconductoring of existing transmission assets, and Dynamic Line Rating (DLR). All of these options except DLR are capital intensive, have long lead times and often experience strong public and regulatory opposition. The Smart Grid Demonstration Program (SGDP) project co-funded by the Department of Energy (DOE) and Oncor Electric Delivery Company developed and deployed the most extensive and advanced DLR installation to demonstrate that DLR technology is capable of resolving many transmission capacity constraint problems with a system that is reliable, safe and very cost competitive. The SGDP DLR deployment is the first application of DLR technology to feed transmission line real-time dynamic ratings directly into the system operation’s State Estimator and load dispatch program, which optimizes the matching of generation with load demand on a security, reliability and economic basis. The integrated Dynamic Line Rating (iDLR)1 collects transmission line parameters at remote locations on the lines, calculates the real-time line rating based on the equivalent conductor temperature, ambient temperature and influence of wind and solar radiation on the stringing section, transmits the data to the Transmission Energy Management System, validates its integrity and passes it on to Oncor and ERCOT (Electric Reliability Council of Texas) respective system operations. The iDLR system is automatic and transparent to ERCOT System Operations, i.e., it operates in parallel with all other system status telemetry collected through Supervisory Control and Data Acquisition (SCADA) employed across the company.

24 POWER TRANSMISSION AND DISTRIBUTION↗

Variability of Photovoltaic Power in the State of Gujarat Using High Resolution Solar Data

India has ambitious goals for high utilization of variable renewable power from wind and solar, and deployment has been proceeding at a rapid pace. The western state of Gujarat currently has the largest amount of solar generation of any Indian state, with over 855 Megawatts direct current (MWDC). Combined with over 3,240 MW of wind, variable generation renewables comprise nearly 18% of the electric-generating capacity in the state. A new historic 10-kilometer (km) gridded solar radiation data set capturing hourly insolation values for 2002-2011 is available for India. We apply an established method for downscaling hourly irradiance data to one-minute irradiance data at potential PV power production locations for one year, 2006. The objective of this report is to characterize the intra-hour variability of existing and planned photovoltaic solar power generation in the state of Gujarat (a total of 1.9 gigawatts direct current (GWDC)), and of five possible expansion scenarios of solar generation that reflect a range of geographic diversity (each scenario totals 500-1,000 MW of additional solar capacity). The report statistically analyzes one year's worth of power variability data, applied to both the baseline and expansion scenarios, to evaluate diurnal and seasonal power fluctuations, different timescales of variability (e.g., from one to 15 minutes), the magnitude of variability (both total megawatts and relative to installed solar capacity), and the extent to which the variability can be anticipated in advance. The paper also examines how Gujarat Energy Transmission Corporation (GETCO) and the Gujarat State Load Dispatch Centre (SLDC) could make use of the solar variability profiles in grid operations and planning.

14 SOLAR ENERGY↗

National Assessment of Energy Storage for Grid Balancing and Arbitrage: Phase 1, WECC

To examine the role that energy storage could play in mitigating the impacts of the stochastic variability of wind generation on regional grid operation, the Pacific Northwest National Laboratory (PNNL) examined a hypothetical 2020 grid scenario in which additional wind generation capacity is built to meet renewable portfolio standard targets in the Western Interconnection. PNNL developed a stochastic model for estimating the balancing requirements using historical wind statistics and forecasting error, a detailed engineering model to analyze the dispatch of energy storage and fast-ramping generation devices for estimating size requirements of energy storage and generation systems for meeting new balancing requirements, and financial models for estimating the life-cycle cost of storage and generation systems in addressing the future balancing requirements for sub-regions in the Western Interconnection. Evaluated technologies include combustion turbines, sodium sulfur (Na-S) batteries, lithium ion batteries, pumped-hydro energy storage, compressed air energy storage, flywheels, redox flow batteries, and demand response. Distinct power and energy capacity requirements were estimated for each technology option, and battery size was optimized to minimize costs. Modeling results indicate that in a future power grid with high-penetration of renewables, the most cost competitive technologies for meeting balancing requirements include Na-S batteries and flywheels.

energy storage↗

Water Use Optimization Toolset Project: Development and Demonstration Phase Draft Report

This report summarizes the results of the development and demonstration phase of the Water Use Optimization Toolset (WUOT) project. It identifies the objective and goals that guided the project, as well as demonstrating potential benefits that could be obtained by applying the WUOT in different geo-hydrologic systems across the United States. A major challenge facing conventional hydropower plants is to operate more efficiently while dealing with an increasingly uncertain water-constrained environment and complex electricity markets. The goal of this 3-year WUOT project, which is funded by the U.S. Department of Energy (DOE), is to improve water management, resulting in more energy, revenues, and grid services from available water, and to enhance environmental benefits from improved hydropower operations and planning while maintaining institutional water delivery requirements. The long-term goal is for the WUOT to be used by environmental analysts and deployed by hydropower schedulers and operators to assist in market, dispatch, and operational decisions.

13 HYDRO ENERGY↗

Operation of Concentrating Solar Power Plants in the Western Wind and Solar Integration Phase 2 Study

The Western Wind and Solar Integration Study (WWSIS) explores various aspects of the challenges and impacts of integrating large amounts of wind and solar energy into the electric power system of the West. The phase 2 study (WWSIS-2) is one of the first to include dispatchable concentrating solar power (CSP) with thermal energy storage (TES) in multiple scenarios of renewable penetration and mix. As a result, it provides unique insights into CSP plant operation, grid benefits, and how CSP operation and configuration may need to change under scenarios of increased renewable penetration. Examination of the WWSIS-2 results indicates that in all scenarios, CSP plants with TES provides firm system capacity, reducing the net demand and the need for conventional thermal capacity. The plants also reduced demand during periods of short-duration, high ramping requirements that often require use of lower efficiency peaking units. Changes in CSP operation are driven largely by the presence of other solar generation, particularly PV. Use of storage by the CSP plants increases in the higher solar scenarios, with operation of the plant often shifted to later in the day. CSP operation also becomes more variable, including more frequent starts. Finally, CSP output is often very low during the day in scenarios with significant PV, which helps decrease overall renewable curtailment (over-generation). However, the configuration studied is likely not optimal for High Solar Scenario implying further analysis of CSP plant configuration is needed to understand its role in enabling high renewable scenarios in the Western United States.

14 SOLAR ENERGY↗

LANL Investigation Report: Magnet Fire Event at TA-53, Line D South

On May 21, 2014, at approximately 2350, an electric magnet fire occurred in the Line D South area of Technical Area 53. Smoke detectors in the supply and return ventilation system ducts activated, sending alarms to the Emergency Operations Support Center (EOSC). Approximately 7 minutes later, a single fire suppression sprinkler actuated. Upon receipt of multiple flow alarms, the Los Alamos Fire Department (LAFD) was dispatched. These first responders concluded this was a false alarm and left the scene prior to the arrival of LANL, or TA-53 personnel. Because of the continued flow of the fire suppression water through the actuated sprinkler, local Radioactive Liquid Waste (RLW) tanks later alarmed on high-level. Further response by the Utilities and Infrastructure (UI) Facility Supervisor and TA-53 facility personnel was focused on stopping the flow of water. These personnel believed the sprinkler actuation and subsequent RLW high level alarms were due to a failed sprinkler head (not an actual fire event).

99 GENERAL AND MISCELLANEOUS↗

Advanced Methods for Incorporating Solar Energy Technologies into Electric Sector Capacity-Expansion Models: Literature Review and Analysis

Because solar power is a rapidly growing component of the electricity system, robust representations of solar technologies should be included in capacity-expansion models. This is a challenge because modeling the electricity system--and, in particular, modeling solar integration within that system--is a complex endeavor. This report highlights the major challenges of incorporating solar technologies into capacity-expansion models and shows examples of how specific models address those challenges. These challenges include modeling non-dispatchable technologies, determining which solar technologies to model, choosing a spatial resolution, incorporating a solar resource assessment, and accounting for solar generation variability and uncertainty.

14 SOLAR ENERGY↗

Western Wind and Solar Integration Study Phase 3 – Frequency Response and Transient Stability

Power system operators and utilities worldwide have concerns about the impact of high-penetration wind and solar generation on electric grid reliability (EirGrid 2011b, Hydro-Quebec 2006, ERCOT 2010). The stability of North American grids under these conditions is a particular concern and possible impediment to reaching future renewable energy goals. Phase 3 of the Western Wind and Solar Integration Study (WWSIS-3) considers a 33% wind and solar annual energy penetration level that results in substantial changes to the characteristics of the bulk power system, including different power flow patterns, different commitment and dispatch of existing synchronous generation, and different dynamic behavior of wind and solar generation. WWSIS-3 evaluates two specific aspects of fundamental frequency system stability: frequency response and transient stability.

14 SOLAR ENERGY↗

Convexity of Energy-Like Functions: Theoretical Results and Applications to Power System Operations

Power systems are undergoing unprecedented transformations with increased adoption of renewables and distributed generation, as well as the adoption of demand response programs. All of these changes, while making the grid more responsive and potentially more efficient, pose significant challenges for power systems operators. Conventional operational paradigms are no longer sufficient as the power system may no longer have big dispatchable generators with sufficient positive and negative reserves. This increases the need for tools and algorithms that can efficiently predict safe regions of operation of the power system. In this paper, we study energy functions as a tool to design algorithms for various operational problems in power systems. These have a long history in power systems and have been primarily applied to transient stability problems. In this paper, we take a new look at power systems, focusing on an aspect that has previously received little attention: Convexity. We characterize the domain of voltage magnitudes and phases within which the energy function is convex in these variables. We show that this corresponds naturally with standard operational constraints imposed in power systems. We show that power of equations can be solved using this approach, as long as the solution lies within the convexity domain. We outline various desirable properties of solutions in the convexity domain and present simple numerical illustrations supporting our results.

24 POWER TRANSMISSION AND DISTRIBUTION↗

Modular Undersea Compressed Air Energy Storage (UCAES) System

This project has been devoted to the design, optimization, and cost analysis of a unique power plant with integral energy storage. The proposed facility combines a novel underwater compressed air energy storage (UCAES) system with a customized gas turbine generator, providing exceptional power management and overall efficiency. Unlike conventional CAES, opportunities for underwater storage are plentiful and proximal to the power grid. The UCAES system provides coastal and island communities a practical means for managing the volatility of large-scale wind and solar power resources. The result is higher renewable energy absorption and improved electrical reliability with reduced fossil fuel consumption. The UCAES power plant is composed of three major subsystems: The underwater air containment system (ACS), the air transport pipe (ATP), and the land-based power conversion system (PCS). The underwater ACS is made up of modular concrete shell units, structurally optimized for minimal material usage while employing conventional production methods and equipment. Each shell is designed to receive and control loose fill or gravel, serving as the ballast. The static nature of the final structures make them an asset to marine habitats and includes features intended to permit safe and cost-effective deployment. The ATP Connects the ACS modules to each other and to the on-land power conversion system and utilizes high density polyethylene (HDPE) pipe for low cost and long life. The PCS Houses the turbine-generator ‘expander modules’, with peak capacity of 12.3 MWe each, engineered from existing gas turbine equipment and includes electrically driven commercial 3-stage intercooled centrifugal compressors, each nominally drawing 6.6 MWe when matching the turbine flow requirements. The subsystems listed above are designed with the intent to serve as building-blocks to achieve a peak power output rating in the 40 to 120 MWe range, with 0.25 to 4 hours of energy storage capacity. The modular facility with integral energy storage provides some remarkable transient maneuvers and load-following features unachievable by competing technologies. The system can operate as a dispatchable power plant with a fuel-to-electric efficiency over 41%; substantially better that the average existing Hawaiian peak power generation assets. Optimal efficiency can be maintained while load-following due to modular PCS design and is operable with a range of liquid or gaseous fuels while meeting the most stringent California (CARB) emission standards. The system can operate as a peaking energy plant in discharge mode. Power ramp-up equivalent to 215% of continuous load rating within 1 second accomplished by simply turning off the electric compressor(s). Contrarily, the system can offer energy absorption during periods of grid surplus generation. The electric compressors may be sequenced on to absorb power within seconds. More moderate transitions are easily achieved with standard compressor control functions. The system offers unique features as compared to energy storage systems. ‘Round-trip efficiency’, as calculated by industry standard methods, is in the 90% range. The PCS equipment has a mean-time between overhauls of 80,000 hours, with maintenance costs of less than $0.005/kW-hr of electricity delivered. The underwater ACS structures and piping employ materials and designs specified to achieve a 75 year life. With the underwater containment modules qualified as a marine habitat, there would be no decommissioning costs. In conjunction with the engineering work invested in the design of the UCAES power plant, Brayton Energy has employed a team of manufacturing specialists, marine construction engineers, and power industry experts to create a comprehensive economic model that captures the many site-related variables and configuration options. The cost results and methodology have been validated by suppliers, engineers, and deployment specialists through a detailed case study on Hawaii. While creation of the parametric cost model was based on inputs specific to Hawaii, the proposed construction and deployment steps were chosen to be general enough to allow extrapolation across locations world-wide. Analysis of the proposed system shows it to be a viable option and addresses the principal challenges described by the Department of Energy by offering competitive costs, validated safety and reliability, consideration of the regulatory environment, and utilization of industry accepted practices and equipment. The UCAES system is recommended for immediate consideration in Hawaii. Estimation of time to complete planning, design, and construction of the facility is anticipated to take 3 to 5 years. Other coastal and island communities world-wide should realize similar benefits; as the results presented in this report are considered generally transferable to other locations.

24 POWER TRANSMISSION AND DISTRIBUTION↗

Stochastic Operations and Planning

This document discusses PNNL's efforts to mitigate the changing patterns of electrical system behavior, how it is dispatched, and exchanges of energy.

24 POWER TRANSMISSION AND DISTRIBUTION↗

Addressing Energy Demand through Demand Response. International Experiences and Practices

Demand response (DR) is a load management tool which provides a cost-effective alternative to traditional supply-side solutions to address the growing demand during times of peak electrical load. According to the US Department of Energy (DOE), demand response reflects “changes in electric usage by end-use customers from their normal consumption patterns in response to changes in the price of electricity over time, or to incentive payments designed to induce lower electricity use at times of high wholesale market prices or when system reliability is jeopardized.” 1 The California Energy Commission (CEC) defines DR as “a reduction in customers’ electricity consumption over a given time interval relative to what would otherwise occur in response to a price signal, other financial incentives, or a reliability signal.” 2 This latter definition is perhaps most reflective of how DR is understood and implemented today in countries such as the US, Canada, and Australia where DR is primarily a dispatchable resource responding to signals from utilities, grid operators, and/or load aggregators (or DR providers).

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

Modeling and Analysis of Wholesale Electricity Market Design. Understanding the Missing Money Problem. December 2013 - January 2015

This project examined the impact of renewable energy sources, which have zero incremental energy costs, on the sustainability of conventional generation. This “missing money” problem refers to market outcomes in which infra-marginal energy revenues in excess of operations and maintenance (O&M) costs are systematically lower than the amortized costs of new entry for a marginal generator. The problem is caused by two related factors: (1) conventional generation is dispatched less, and (2) the price that conventional generation receives for its energy is lower. This lower revenue stream may not be sufficient to cover both the variable and fixed costs of conventional generation. In fact, this study showed that higher wind penetrations in the Electric Reliability Council of Texas (ERCOT) system could cause many conventional generators to become uneconomic.

16 TIDAL AND WAVE POWER↗