Nuclear Hybrid Energy Systems Research Articles

Dynamic modeling and simulation of advanced nuclear reactor with thermal energy storage

AbstractThe increasing installment of solar and wind renewable energy systems create a volatile energy demand to be met by electricity providers. A nuclear hybrid energy system is a nuclear reactor with energy storage that integrates into the grid with renewable energy sources. The Natrium design by TerraPower and GE Hitachi is a sodium fast reactor with molten salt energy storage. The Natrium design operates at steady state of 345 MWe and can boost up to 500 MWe for 5.5 hours. This study uses Dymola and the Modelica language to model the Natrium‐based nuclear‐renewable hybrid energy system. The dynamic system model is tested using hourly historical data from the state of Texas 2021 to show how renewables affect the electricity demand and how energy storage affects the Natrium system response to the demand. According to the results, while the available storage will allow the Natrium design to boost electricity production when the demand and electricity price is high making it more economically viable, the current molten salt storage is slightly undersized for the ERCOT market.

Modeling and simulation of nuclear hybrid energy systems architectures

Modeling and simulation of nuclear hybrid energy systems architectures

Solar and sodium fast reactor-based integrated energy system developed with thermal energy storage and hydrogen

Hybridizing nuclear and renewable energy systems helps enhance the benefits of both sources and eliminate their disadvantages. In order to provide resilience, energy systems need to be designed in a complementary manner to achieve an uninterrupted energy supply. The current study proposes a hybridization of a sodium fast reactor with a concentrated solar plant and molten salt energy storage system. By considering the community requirements, additional subsystems are added that use process heat and power to generate more useful commodities. The proposed nuclear and renewable hybrid energy system generates heat, power, hydrogen, fresh water, and cooling effect for communities in order to meet their needs in a sustainable fashion. The proposed system is a potential alternative to currently available fossil fuel-driven systems. Intermittency and flexibility issues of such systems are overcome with hybridization and integration. Apart from the other commodities, hydrogen is produced and supplied to the community by considering hydrogenization along with the electrification of transportation. Specifically, a parabolic trough collector-type concentrated solar plant, a sodium-cooled fast reactor, a molten salt energy storage unit, a lithium bromide absorption refrigerator, a solid-oxide electrolyser, a multi-effect distillation-type desalination unit, and a district heating system are considered to be used in the integrated system. The proposed system is investigated by considering the first and second laws of thermodynamics, which assess energy and exergy inputs and outputs of the system and subsystems. In order to analyze the system with realistic conditions, actual data for California, the United States, is considered. For a community with 240243 residents, a sodium fast reactor with 1.5 GWth capacity and parabolic trough collectors with 0.5 GWth capacity are considered, along with a 4 GWh of molten salt energy storage system. Annual average energy and exergy efficiencies are found to be 63.54 % and 57.96 %. The maximum energy efficiency is calculated as 84.4 %, and the maximum exergy efficiency is found as 81.28 %. Apart from the current community needs, 53,285.15 tonnes of hydrogen is produced annually.

Small modular reactors for green remote mining: A multi-objective optimization from a sustainability perspective

Nuclear energy sources, in particular the small modular reactor (SMR), are being recognized as low-emission clean energy sources. The development of SMRs has focused on minimizing their carbon footprint while ensuring that energy is generated in a safe and cost-competitive manner, which leads to a worldwide growing interest in SMR deployments. In addition, there is a strong demand for renewable energy sources; however, their output can be influenced significantly by weather and location. Therefore, integration of renewable energy sources with SMRs and an energy storage system, which results in a nuclear renewable hybrid energy system (NR-HES), is required to improve power generation reliability. NR-HES represents a promising energy system solution for off-grid communities and industries, especially those involving remote mining sites. In the present study, an off-grid NR-HES to meet electrical and thermal demands is considered for the Victor mine site in northern Ontario, Canada. Off-grid remote mines in Canada primarily rely on diesel generators. The proposed NR-HES is composed of SMR units with a thermal capacity of 15 MWth each, two wind turbines with a capacity of 2.3 MWe each, a two-tank molten salt thermal storage system, a hydrogen storage facility, and peaking diesel generators. To achieve a near-zero-emission mining site, electric vehicles are proposed in the mining site energy demand structure. A transient thermodynamics model is developed to simulate the NR-HES and generate hourly variation of sustainability performance parameters that include power cycle efficiency, SMR capacity factor, round-trip efficiency of the storage systems, thermal storage state of charging, and greenhouse gas emissions. In addition, an economic analysis is performed to determine the additional annualized cost of the system relative to a baseline site. The simulation has a test matrix of 16 runs with various combinations of design input parameters, namely SMR thermal power, storage duration (e.g., daily, seasonally, or monthly), and thermal storage system volume. Grey relational analysis (GRA) is used as a level-based multi-objective optimization technique to determine the nearest optimal design parameter (e.g., decision variable) combination within the test matrix and thus the optimal configuration. In addition, the GRA ranks the design input parameters based on how significantly each parameter can affect the overall performance of the NR-HES. Results revealed that optimal sustainable perspectives have a significant influence on the overall system parameters and performance. For instance, the results showed that there is an opportunity to achieve a reduction in greenhouse gas emissions by 94.8% with a minimal impact to system annualized cost if the cost and environmental effect objectives were prioritized over other sustainability performance parameters.

A Multi-Scale method for combined design and dispatch optimization of nuclear hybrid energy systems including storage

Reliable, carbon-free power generation is increasing in importance. Nuclear-renewable hybrid energy systems (NHES) are a potential solution for current generation challenges, but design and dispatch optimization for these systems remains challenging particularly when stochastic effects, long time horizons and nonlinear modeling are needed. This work presents a multi-scale method for combining the design and dispatch optimization problems for nonlinear NHES over long time horizons. Rather than treating the entire horizon as a single optimization problem, a large number of combined optimization problems are solved for shorter samples of the horizon resulting in distributions of optimal capacities for each of the capacities being optimized. The distributions are then aggregated, and the techno-economics of each aggregate is analyzed. The result is a contextual knowledge about the techno-economic tradeoffs for the system rather than a single set of optimal capacities. This method is applied to two NHES of varying complexity. Results indicate that unit capacities for a grid-connected district energy system can be reduced by at least 18.9% by allowing for 3 periods of power import over the course of a 2000 day dispatch. The algorithm is used to solve combined optimization problems with dispatch horizons 112.5 times longer than are solvable directly.

THE DEVELOPMENT STRATEGY OF UKRAINE'S ENERGY SYSTEM AND THE PLACE OF SMALL MODULAR REACTORS IN IT

The paper describes the characteristics of small modular reactors (SMR), their differences from existing nuclear power plants and the features of their use in modern hybrid electric power systems in combination with renewable energy sources and Nuclear Renewable Hybrid Energy System (NRHES) electricity storage, their advantages and problems of use in the future power system of Ukraine. Prospects for cooperation in this area with companies from the United States of America were considered. Small modular SMR reactors are suitable for electrical systems of various capacities, their modular system allows flexibility and speed of construction, reduces capital investment needs and eases financing requirements. The smaller size and variety of reactors can also mean that they can be built in locations not traditionally suitable for large nuclear power plants and, importantly, near energy-intensive industries or remote communities, i.e. as elements of distributed generation. They can ensure a reliable supply of not only electricity, but also heat. SMRs can also be deployed at decommissioned coal-fired power plants. Taking advantage of existing infrastructure, including switchgear and coal-fired turbines, could reduce SMR construction costs and avoid the need to add new transmission lines from these facilities. Problems with the implementation of such networks are revealed. Attention was drawn to the increased complexity of the system in connection with the use of various sources of generation and processes of distribution and consumption of electricity. The main technical characteristics, features of the reactor design, the station building, safety systems and control systems are given. The study concludes that SMRs have significant advantages for use in modern networks, due to their modular design and modular deployment, to meet a variety of power switching and scaling requirements.

Techno-economic sensitivity analysis for combined design and operation of a small modular reactor hybrid energy system

With increasing grid-penetration of renewable energy resources and a rising need for carbon-free dispatchable power generation, nuclear-hybrid energy systems (NHES), consisting of small modular reactors, are an increasingly attractive option for maintaining grid stability. NHES can accomplish this with a minimal carbon footprint but there are significant uncertainties that are not fully understood. This work describes and demonstrates methods for analyzing the uncertainties of potential NHES designs, including uncertain design parameters and time series as well as variations in dispatch horizon length. The proposed methods are demonstrated on a sample system with 16 design parameters, 3 uncertain time series, and a range of dispatch horizon lengths where the unit capacities and unit dispatch are co-optimized to minimize system LCOE. For the example system, 11 of 16 parameters are uncorrelated with model outputs, allowing for model reduction without decreased accuracy. It is determined that the impact of variation in multiple time series cannot be easily isolated and that the examined sources of uncertainty are of similar importance in terms of overall impact. • Optimize SMR-renewable hybrid energy system design with uncertain parameters. • Quantify design changes with forecasts as stochastic time series. • Investigate optimal dispatch and design with varying horizon length. • Method for sensitivity analysis of combined design and dispatch of SMR hybrid energy systems.

Coupling Chemical Heat Pump with Nuclear Reactor for Temperature Amplification by Delivering Process Heat and Electricity: A Techno-Economic Analysis

The energy economy is continually evolving in response to socio-political factors in the nature of primary energy sources, their conversions to useful forms, such as electricity and heat, and their utilization in different sectors. Nuclear energy has a crucial role to play in the evolution of energy economy due to its clean and non-carbon-emitting characteristics. A techno-economic analysis was undertaken to establish the viability of selling heat along with electricity for an advanced 100 MWth small modular reactor (SMR) and four nuclear hybrid energy system (NHES) configurations featuring the SMR paired with chemical heat pump (ChHP) systems providing a thermal output ranging from 1 to 50 MWth. Net present value, payback period, discounted cash flow rate of return, and levelized cost of energy were evaluated for these systems for different regions of U.S. reflecting a range of electricity and thermal energy costs. The analysis indicated that selling heat to high temperature industrial processes showed profitable outcomes compared to the sale of only electricity. Higher carbon taxes improved the economic parameters of the NHES alternatives significantly. Providing heat to high temperature industries could be very beneficial, helping to cut down the greenhouse gases emission by reducing the fossil fuel consumption.

A nuclear‑hydrogen hybrid energy system with large-scale storage: A study in optimal dispatch and economic performance in a real-world market

A study in optimal dispatch and economic analysis of a novel nuclear hybrid energy system (NHES) with large-scale hydrogen storage and a novel control scheme is conducted. The control scheme makes charge and discharge decisions by using the real-time electricity price relative to the historical price distribution. The pricing data is taken from the ERCOT Houston and West load zones with different price oscillations. Six case control studies with different levels of aggressiveness were chosen for each load zone for a total of 12 case studies. It is found that in a high price volatility load zone, a more aggressive control strategy maximizes revenue, while in a less oscillatory load zone, a moderate control strategy performs better. The NHES can store energy when the price is low and sell additional electricity when the price is high, as well as participate in the ancillary services market. Due to these advantages, the NHES can generate 10–40 million USD more revenue annually than a stand-alone nuclear plant. Due to higher costs, the NHES has a higher LCOE (81.36 USD/MWh) than a stand-alone plant (68.66 USD/MWh); however, the LCOE of the NHES is still comparable to other new forms of electricity generation. It is found that both the NHES and the stand-alone plant are not economical in the existing electricity market. Due to the extra revenue generated, the hybrid system has a positive annual cashflow whereas the stand-alone plant does not. It is found that the hybrid plant needs less cost subsidy than a stand-alone plant to become economical.

Applying analytic hierarchy process to industrial process design in a Nuclear Renewable Hybrid Energy System

Nuclear Renewable Hybrid Energy Systems (NRHESs) co-locate a nuclear power plant with a renewable power generation source, such as solar or wind, with an industrial process(es), and can include a battery for energy storage and a fossil fuel power plant. By co-locating these various components, the nuclear-generated power can be directed to the industrial process when demand is low or renewable generation is high, as well as toward meeting grid demand when needed. This paper will apply the risk assessment and management technique of the fuzzy Analytical Hierarchy Process (AHP) to an NRHES. The goal is to develop a method of evaluating industrial components in preliminary NRHES design. Criteria selected in this study within which each process is assessed are profitability, flexible operation, and safety. Based on this, the fuzzy AHP approach determined desalination to be the strongest candidate based on system definition and related assumptions. Additional studies can be undertaken using this approach for more in depth analysis of NRHES design. With no NRHESs currently deployed, fuzzy AHP can offer a useful decision-making tool.

Dynamic modeling and simulation of nuclear hybrid energy systems using freeze desalination and reverse osmosis for clean water production

Nuclear hybrid energy systems (NHES) are a viable option to combine renewable energy sources, such as wind, with a less fluctuating energy source. Given recent development and their inherent safer and modular design, small modular reactors (SMRs) can play an instrumental role in complementing renewables and supporting carbon-free power sectors in the coming decades. This study uses OpenModelica to model two types of NHES to produce clean energy and water, both powered by SMRs and wind turbines. The first system uses freeze desalination (FD), and the second system uses reverse osmosis (RO) to generate clean water. Both systems are simulated using input data for Salt Lake City, Utah on a hot summer day. The number of SMRs and wind turbines are set so as to meet the power demand for the city. The FD system was able to boost the power production by about 12% by making the steam cycle over 2% more efficient. This allows the system to meet the power demand during peak hours. Although the RO system underperformed in meeting the power demand during the peak hours, it was able to generate approximately six times the amount of clean water as generated by the FD system.

Dynamic simulation of a novel nuclear hybrid energy system with large-scale hydrogen storage in an underground salt cavern

In this study, a nuclear hybrid energy system (NHES) with large-scale hydrogen storage integrated with a gas turbine cycle is proposed as a flexible system for load following. The proposed system consists of a nuclear reactor, a steam Rankine cycle, a hydrogen electrolyzer, a storage system for hydrogen in an underground salt cavern, and a Brayton cycle that uses hydrogen as fuel to generate additional electricity to meet peak demand. A dynamic mathematical model is developed for each subsystem of the NHES. To evaluate the potential benefits of the system, a one-year study is conducted, using scaled grid demand data from ISO New England. The dynamic simulation results show that the system is capable of meeting the demand of the grid without additional electricity from outside sources for 93% of the year, while decreasing the number of ramping cycles of the nuclear reactor by 92.7%. There is also potential for economic benefits as the system only had to ramp up and down 7.4% of the year, which increased the nuclear capacity factor from 86.3% to 98.3%. The simulation results show that the proposed hybrid system improves the flexibility of nuclear power plants, provides more electricity, and reduces greenhouse gas emissions.

FUEL CYCLE IMPLICATIONS OF DEPLOYING HTGRS IN HYBRID ENERGY SYSTEMS AS RESERVE POWER GENERATION IN ONTARIO

Nuclear power plants could potentially be deployed in a type of nuclear hybrid energy system (NHES) in which their power is used primarily to drive an industrial process but can be diverted to meet demands for electricity when needed. The purpose of this study is to analyze the effects of deploying NHESs as reserve power for the transmission grid in Ontario on the overall Canadian fuel cycle. In this scenario, the fuel cycle demands of 2 high-temperature gas-cooled reactor (HTGR) concepts are analyzed with respect to costs, resource consumption, and enrichment requirements. One HTGR concept is a 30 MW-thermal (MWth) reactor that is based on the UBattery concept, and the other is the Xe-100, which is a 200 MWth reactor. Calculations indicate that such a deployment of HTGRs would have a substantial effect on the fuel cycle in Canada. In particular, NU and enrichment demands would be greatly affected. Beginning this HTGR deployment in the year 2030 would more than double the annual NU demands in Canada, and deplete the uranium resources with extraction costs of <$80/kgU by the year 2142. The uranium enrichment demands of this fleet would be >35% of the US capacity for uranium enrichment.

Nuclear renewable hybrid energy system assessment through the thermal storage system

In support of the use of more efficient and low-carbon nuclear energy along with solar energy in power generation systems, the present paper presents a technical-economic analysis of a nuclear renewable hybrid energy system (NR-HES) case study for a given electricity and residential heat demand profiles of a typical remote community in Canada. The studied hybrid energy system is composed of a small modular nuclear reactor (SMR), a concentrated solar tower (CST), and a thermal energy storage (TES) unit. A fossil fuel backup energy source is also considered to generate excess electricity as needed. The CST and nuclear reactor both share the same TES system. Five different thermal storage fluids are examined: Therminol, Dowtherm, solar salt, Hitec salt, and Hitec XL salt. A transient thermodynamic mathematical model is developed in order to determine the overall configuration, performance, and operation strategy for the NR-HES. The operational strategy of the NR-HES is based on the steady-state full-power operation of the SMR, storing the excess energy in the TES system when the combined nuclear and solar power generation exceeds the power demand of the electrical grid and using the stored thermal energy during the periods of peak demand A detailed economic analysis of the NR-HES is conducted for each operational scenario, including the annualized cost of the TES system and the NR-HES plant, as well as annual revenue and profit generated by the TES system. The developed model is used to obtain the most economical thermal storage fluid and to optimize the size of TES system in order to minimize the use of fossil fuels and maximize profit. Parametric studies of reactor thermal power and CST's field area are conducted to determine their effect on the performance and configuration of the NR-HES. Based on the current case study in terms of demand profiles, the results revealed that Therminol is the most economical thermal storage fluid for the present NR-HES with a charging capacity and round-trip storage efficiency of 237 268 MWh/year and 96%, respectively. The optimum Therminol storage tank size is evaluated to be 14 m in height and 10 m in diameter with a yearly average power cycle efficiency of ~36% and economic profit of 1 158 30 CAD/year. The parametric studies indicated that a larger TES size may decrease the usage of fossil fuel energy sources; however, it increases system total capital cost and decreases the power cycle efficiency and TES profit at given load. The results of this study indicate that an NR-HES is a promising low-carbon power generation system with the potential to meet the electricity and residential heat demand of remote communities.

Economic analysis of a nuclear hybrid energy system in a stochastic environment including wind turbines in an electricity grid

The electricity market in the U.S. is moving toward an energy mix including more variable renewable energy (VRE) sources like wind and solar. This increasing VRE penetration is altering the profile of the net electricity demand. Traditionally, flexible generators (e.g. gas turbines) are used to absorb fluctuations in the electricity demand. Therefore, an increase in VRE also leads to an increase in installed capacity for such flexible generators which, in turn, may increase the price of electricity. Nuclear-Renewable Hybrid Energy Systems (N-R HES) are seen as a solution to this problem. The N-R HES contains a nuclear power plant electrically and/or thermally linked to an industrial process (IP). This paper demonstrates a new methodology and presents the corresponding RAVEN/Modelica-based software framework to evaluate the financial performance of N-R HES. The novelty of the method is that it explicitly incorporates the stochastic nature of N-R HES inputs such as electricity demand and wind speeds. The method is applied to a generic (rather than region-specific) N-R HES. The analysis shows that under the right market conditions, economic benefits can be achieved by adding a suitable IP to the base-load generator. In particular, there exists an optimal relationship between the IP capacity and the demand. Global trends also indicate VRE penetration raises the cost of electricity due to the added volatility, an issue only mitigated when operating with high profit margins for the IP.

The state of progress and associated challenges in the global deployment of small modular reactors

Small Modular Reactors (SMRs) represent an innovative class of reactors with the advantages demonstrated through the reliable history of the current fleet coupled with a unique operational paradigm that may facilitate their deployment. This paradigm refers to new markets: nuclear hybrid energy systems; baseload generation to back intermittent renewable sources or process heat applications; decentralised electricity grid generation, where electricity demand may not support large reactors or the water supply is limited; and construction of single modules at a time, allowing new investors to enter the market with lower investments risks. With the increase in wind and solar generation worldwide, the inherent electricity grid and market fluctuations must be addressed. SMRs offer one potential solution; however, the social, political, and economic challenges must be overcome in regions where nuclear power is already prevalent. Other obstacles exist in new nuclear markets, including the development of a regulatory body and supply chain.

Production Possibilities of a Sustainable Coal, Wind, and Small Modular Reactor Hybrid Energy System

The availability of inexpensive electricity is one of the most significant factors for improving quality of life. With the debate on the effects of carbon dioxide emissions continuing, several countries either have implemented or are considering the reduction of emissions through various economic means. The inclusion of a monetary penalty on carbon emissions would increase the prices of electricity produced by carbon-based sources. The push for large-scale renewable sources of energy has met problems with regards to energy storage and availability. The proposed coal, wind, and nuclear hybrid energy system would combine a renewable energy source, wind, with traditional and stable energy sources, coal and nuclear, to create an integrated and sustainable system. Instead of a light water reactor, a next generation small modular nuclear reactor was evaluated. The coal system utilizes a pressurized circulating fluidized bed system, which can take not only coal but also biomass as a carbon feedstock. This system...

Enhancing Electric Grid, Critical Infrastructure, and Societal Resilience with Resilient Nuclear Power Plants (rNPPs)

This paper, the fourth in a series, presents the results of a study conducted to explore the role current U.S. commercial nuclear power plants (NPPs) play and the role a new type of NPP—a resilient nuclear power plant (rNPP)—could play in enhancing U.S. electric Grid, Critical Infrastructure, and societal resilience. A rNPP is a NPP intentionally designed, sited, interfaced, and operated in a manner to enhance Grid resilience. Four specific rNPP applications are discussed: (1) rNPPs as “flexible operations” electricity generation assets, (2) rNPPs as anchors of nuclear hybrid energy systems, (3) rNPPs as Grid Black Start Resources, and (4) rNPPs as anchors of Resilient Critical Infrastructure Islands. These four applications, individually and collectively, could enhance U.S. Grid, Critical Infrastructure, and societal resilience during normal conditions and in the wake of major national calamities stemming from natural hazards and/or malevolent human actions. rNPPs would be both tactical and strategic resilience assets, thereby extending the value proposition of nuclear energy well beyond that associated with nuclear power’s traditional baseload electricity generation. These are important topics as society grows increasingly dependent on electricity, and the natural hazard and malevolent human threat portfolio to the Grid continues to evolve.

Fault Propagation and Effects Analysis for Designing an Online Monitoring System for the Secondary Loop of the Nuclear Power Plant Portion of a Hybrid Energy System

This paper studies the propagation and effects of faults in critical components that pertain to the secondary loop of a nuclear power plant found in nuclear hybrid energy systems (NHESs). This information is used to design an online monitoring (OLM) system that is capable of detecting and analyzing faults that are likely to occur during NHES operation. In this research, the causes, features, and effects of possible faults are investigated by simulating the propagation of faults in the secondary loop of a nuclear power plant. The simulation is conducted using Integrated System Failure Analysis (ISFA), a promising method analyzing hardware and software faults during the conceptual design phase. First, the models of system components required by ISFA are constructed. Then, fault propagation analysis is implemented, which is conducted under the bounds set by acceptance criteria derived for the design of an OLM system. The result of the fault simulation is utilized to evaluate the effectiveness of signals for fault detection and diagnosis and to propose an optimization plan for the OLM system. Finally, several experiments are designed and conducted using a hardware-in-the-loop system to verify the correctness and effectiveness of the proposed method.

Optimal sizing of flexible nuclear hybrid energy system components considering wind volatility

This paper seeks to quantify the benefits of a flexible energy system in the context of enabling higher levels of variable renewable energy on the grid. We explore a nuclear hybrid energy system (NHES) consisting of a 300 MW small modular reactor, wind generation, battery storage, and a reverse osmosis desalination plant. A dispatch rule is constructed within the Risk Analysis Virtual Environment (RAVEN) to model the system. Stochastic optimization and parametric analysis are utilized to explore how increased volatility in the net demand resulting from higher levels of wind penetration affect the optimal solution, and the stability of the system’s levelized cost of electricity (LCOE). In this study, net demand is the demand minus wind generation. This work contributes multi-objective analysis implemented through a supply-demand mismatch penalty to illustrate the financial stability and operational reliability benefits of the flexible energy system. In this context, we find that the additional up front cost of flexible loads and energy storage result in greater stability in LCOE as volatility in the demand increases. Additionally, the flexibility results in increased reliability in terms of meeting the demand. Although the analysis is conducted on a NHES, we emphasize the flexibility of the method applied here, in that the RAVEN platform and the multi-objective strategy are widely applicable to the analysis of energy systems faced with uncertainties in supply and demand.