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Nuclear reactors produce heat and thus can couple to heat storage systems to provide dispacthable electricity while the reactor operates at full power. Six classes of heat storage technologies couple to light-water reactors with steam cycles. Firebrick Resistance-Heated Energy Storage (FIRES) converts low-price electricity into high-temperature sto...
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... coupled to the high-temperature Brayton cycle and a firebrick recuperator that is coupled to the lower-temperature HRSG. Air is the heat transfer medium for both storage systems. The HRSG could also be coupled to the steam cycle storage technologies that were described earlier. One NACC system design with alternative operating modes is shown in Fig. 10. This specific NACC design is based on the GE F7B NGCC and requires no advances in gas turbine technology. Significant development work is required on the reactor coolant-to-air heat ...
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... This characteristic allows VRES to set wholesale market prices during periods of high production (CAISO 2016), namely the middle of the day. During such periods, market prices can be near-zero or negative (Forsberg et al. 2018) to minimize VRES curtailment. These conditions create a system where traditional power plants, such as coal, natural gas, and nuclear, must operate cyclically to avoid financial losses from midday negative pricing schedules and to meet demand when renewables go offline later in the day. ...
For nuclear power plants to remain competitive in energy markets increasingly penetrated by variable renewable energy sources, designs that allow flexible operation or incorporate additional revenue streams should be considered. This study models a nuclear reactor decoupled from a supercritical steam Rankine cycle through a two-tank thermal storage system using molten salt as the heat transfer fluid. The model allows steam extraction from the power cycle’s low-pressure turbine to provide thermal energy to a thermal desalination facility. The desalination facility likewise includes a two-tank thermal storage system. This study aims to determine the conditions under which thermal storage integrated with nuclear-desalination systems increases economic competitiveness compared to standalone nuclear power plants. We built a mixed-integer linear program that determines optimal dispatch schedules and subsystem sizing of the energy storage components given current price parameters in the literature. We then performed sensitivity analyses to turbine size, thermal storage system cost, and desalinated water price. We found that multi-effect distillation increased the revenue generation of the system beyond standalone conditions except when the price of desalinated water decreased beyond 30% of its nominal 2021 price. We also found that when the turbine is oversized, high-temperature and low-temperature thermal storage is dispatched in a complementary fashion that allows for load-following and continuous distillate production.
... SMRs are fourth-generation reactors, and as such, are designed to be much safer than previous generations of nuclear reactors (Cho, 2019;Hussein, 2020). SMRs are capable of generating heat at almost any pressure and as such are suitable to supply heat too difficult to decarbonize/electrify locations in the same manner that hydrogen has been proposed (Forsberg et al., 2018;Forsberg, 2020;World Economic Forum, 2021;USDOE 2023c;World Nuclear News, 2023). ...
In 2015, during the lead up to the Paris Climate Agreement, the United States set forth a Nationally Determined Contribution that outlines national goals for greenhouse gas emission reductions. It was not until 2021 that the US put forth a long-term strategy that lays out the pathway to reach these goals. The US long-term strategy lays the framework for research needs to meet the greenhouse gas emission reduction goals and incentivizes industry to meet the goals using a variety of policies. The five US long term strategy core elements are to decarbonize electricity, electrify end uses and switch to clean fuels, cut energy waste, reduce methane and other non-carbon dioxide greenhouse gas emissions and to scale up carbon dioxide removal. Implementation of the long term strategy has generally been funded by tax incentives and government grants that were approved as part of the Inflation Reduction Act. Political headwinds, societal Not in My Backyard resistance, long-term economic funding, cumbersome permitting requirements and incentives vs. taxation debate are significant policy/non-technical hurdles. Technical challenges remain regarding effective energy efficiency implementation, the use of hydrogen as a fuel, cost effective carbon emission treatment, nuclear energy expansion, renewables expansion and grid integration, biofuel integration, efficient and safe energy storage and electrical grid adequacy/expan-sion. This review article condenses the multitude of technical and policy issues facing the US long-term strategy, providing readers with an overview of the extent and magnitude of the challenges while outlining possible solutions.
... Several other studies considered nuclear reactors coupled with different types of TES systems for enhanced flexibility. These TES systems included geothermal heat storage [17], molten-salt tanks [18], hot rock storage [19], cryogenic air [20] and compressed carbon dioxide energy storage systems [21]. These studies demonstrated the benefits arising from enhanced flexibility when integrating nuclear reactors with TES and secondary power cycle systems. ...
Nuclear power plants are expected to make an important contribution to the decarbonisation of electricity supply alongside variable renewable generation, especially if their operational flexibility is enhanced by coupling them with thermal energy storage. This paper presents a system modelling approach to identifying configurations of flexible nuclear plants that minimise the investment and operation costs in a decarbonised energy system, effectively proposing a system-driven design of flexible nuclear technology. Case studies presented in the paper explore the impact of system features on plant configuration choices. The results suggest that cost-efficient flexible nuclear configurations should adapt to the system they are located in. In the main low-carbon scenarios and assuming standard-size nuclear power plants (1,610 MWel), the lowest-cost system configuration included around 500 MWel of additional secondary generation capacity coupled to the nuclear power plants, with 4.5 GWhth of thermal storage capacity and a discharging duration of 2.2 h. Net system benefits per unit of flexible nuclear generation for the main scenarios were quantified at £29-33 m/yr for a wind-dominated system and £19-20 m/yr for a solar-dominated system.
... The above reasons make it expedient to search for ways to organize the maneuvering mode of nuclear power plants while maintaining the same basic mode of reactor installations [3][4][5][6]. One of these ways can be the deployment of systems that allow for accumulating the thermal energy of reactors during night hours of reduced power consumption and use it to generate additional electricity during hours of increased power consumption [7,8]. ...
In the context of the growing share of nuclear power plants in the energy systems of the European part of Russia and the shortage of flexible generating capacities, it becomes necessary to involve nuclear power plants in covering the variable part of the load schedule. With relatively low prices for nuclear fuel (at present, the equivalent cost of a uranium fuel load is five to six times lower than the cost of natural gas inside the country) and high specific capital investments in nuclear power plants, it is not economically efficient to unload them. Therefore, the combination of nuclear power plants with latent heat thermal energy storage (LHTES) and an additional steam turbine makes it possible to accumulate thermal energy generated at night and use it during peak hours to generate electricity with the maximum use of nuclear fuel, i.e., without changing the power of the nuclear reactor. In addition, the presence of an additional turbogenerator in emergency situations with a complete blackout of the NPP makes it possible to ensure the operation of the cooling systems by using the residual heat of the reactor to drive the turbine and, thereby, increase the safety level of the NPP. The analysis of prices for electricity in the wholesale electricity and capacity market of the Unified Energy System of Russia (WECM UES) and in the energy system of France (with the highest share of nuclear power plants) was carried out. The impact of the operation of the NPP power unit with a thermal energy storage system was assessed in addition to the alternative option: the construction of a pumped storage power plant (PSPP) at the WECM. Calculations of technical and economic indicators of the use of LHTES-based thermal energy accumulators at NPPs are carried out depending on the level of thermal power of the latter as well as the increase in the regulation range for electricity supply. It is shown that if we do not take into account the multifunctional properties of the energy complex based on LHTES and an additional turbine (increased safety, NPP participation in primary frequency control) with the existing difference in prices for electricity generated during peak and night periods on the day-ahead market, the payback of the NPP energy complex for LHTES-based is not provided. The return on investment in phase-change batteries and an additional turbine in the considered example can be achieved provided that the difference between the average prices for electricity generated during peak and night hours over a billing period of 25 years is 3400 rubles/(MW h) and the charging time/LHTES discharge exceeds 7 h per day.
... Названные причины делают целесообразным поиск путей организации маневренного режима АЭС при сохранении неизменного базового режима реакторных установок [3][4][5][6]. Одним из таких путей может стать размещение систем, позволяющих аккумулировать тепловую энергию реакторов в ночные часы сниженного энергопотребления и использовать ее для генерации дополнительной электроэнергии в часы повышенного энергопотребления [7,8]. Благодаря использованию аккумулирующих установок, таких как тепловые аккумуляторы фазового перехода, в сочетании с баками горячей воды, способными запасать тепловую энергию реакторных установок в часы спада нагрузки в энергосистеме, вместе с дополнительной паровой турбиной можно повысить системную эффективность АЭС. ...
В условиях роста доли атомных электростанций в энергосистемах европейской части России и дефиците маневренных генерирующих мощностей возникает необходимость привлечения АЭС к покрытию переменной части графика нагрузок. При относительно низких ценах на ядерное топливо (в настоящее время эквивалентная стоимость урановой топливной загрузки в 5–6 раз ниже стоимости природного газа внутри страны) и высоких удельных капиталовложениях в АЭС разгружать их экономически неэффективно. Поэтому комбинирование АЭС с тепловыми аккумуляторами фазового перехода (АФП) и дополнительной паровой турбиной позволяет аккумулировать тепловую энергию, выработанную в ночное время, и использовать ее в часы пиковых нагрузок для выработки электроэнергии при максимальном использовании ядерного топлива, т.е. без изменения мощности ядерного реактора. Кроме того, наличие дополнительного турбогенератора в аварийных ситуациях с полным обесточиванием АЭС дает возможность обеспечить работу систем расхолаживания за счет использования остаточного тепловыделения реактора для привода турбины и повысить тем самым уровень безопасности АЭС. Проведен анализ цен на электроэнергию на оптовом рынке электроэнергии и мощности Единой энергетической системы России (ОРЭМ ЕЭС) и в энергосистеме Франции (с самой высокой долей АЭС). Оценено влияние эксплуатации энергоблока АЭС с системой аккумулирования тепловой энергии и альтернативного варианта – строительства гидроаккумулирующей электростанции (ГАЭС) на ОРЭМ. Проведены расчеты технико-экономических показателей использования на АЭС аккумуляторов тепловой энергии на основе АФП в зависимости от уровня тепловой мощности последних, а также достигаемого увеличения регулировочного диапазона по отпуску электроэнергии. Показано, что если не учитывать многофункциональные свойства энергокомплекса на основе АФП и дополнительной турбины (повышение безопасности, участие АЭС в первичном регулировании частоты) при существующей разнице цен на электроэнергию, выработанную в пиковый и ночной периоды, на рынке на сутки вперед, окупаемость энергокомплекса АЭС на основе АФП не обеспечивается. Окупаемость инвестиций в аккумуляторы фазового перехода и дополнительную турбину в рассмотренном примере может быть достигнута при условии, что разность средних за расчетный период 25 лет цен на электроэнергию, выработанную в пиковые и ночные часы, составляет 3400 руб/(МВт · ч) и время зарядки/разрядки АФП превышает 7 ч в сутки.
... Coupling is present in both nuclear technology and in nuclear software development, it describes the interdependence, coordination, or information flow either between components within a nuclear reactor [6,7] or between physical and mathematical models or code structure within a nuclear code [8][9][10]. In nuclear technology development the components, such as reactor cores, pressurizers, steam generators, turbines, and condensers are drafted, assembled, safety proven, and operate together. ...
Traditionally, the complex coupled physical phenomena in nuclear reactors has resulted in them being treated separately or, at most, simplistically coupled in between within nuclear codes. Currently, coupling software environments are allowing different types of coupling, modularizing the nuclear codes or multi-physics. Several multiscale and multi-physics software developments for LWR are incorporating these to deliver improved or full coupled reactor physics at the fuel pin level. An alternative multiscale and multi-physics nuclear software development between NURESIM and CASL is being created for the UK. The coupling between DYN3D nodal code and CTF subchannel code can be used to deliver improved coupled reactor physics at the fuel pin level. In the current journal article, the second part of the DYN3D and CTF coupling was carried out to analyse a parallel two-way coupling between these codes and, hence, the outer iterations necessary for convergence to deliver verified improved coupled reactor physics at the fuel pin level. This final verification shows that the DYN3D and CTF coupling delivers improved effective multiplication factors, fission, and feedback distributions due to the presence of crossflow and turbulent mixing.
... The volumetric sensible heat storage capacity of firebrick systems falls in the range of 0.5-1.0 MWh/m 3 -K, and averages about 90 kWh/m 3 [28]. A significant issue with firebrick is that it must be designed to be at least 3x the needed power capacity in order to compensate for its slow ramping time and energy interdependency [29]. ...
... Steam accumulator technology is already at an advanced stage and has long been in use, coupled with boilers across various industries [28]. Thus, this technology is evaluated to be TRL 9, and was assigned an FOM of 2 for readiness level. ...
... Summary of data available in the literature on molten salts, solid media, and thermochemical materials[7,11,28,[36][37][38][39][40][41][42][43][44][45][46][47]. ...
Advanced nuclear power plants (NPPs) will potentially need to operate in environments where power generation flexibility is more highly valued than the stability or baseload generation capability for conventional demand curves. Thermal energy storage (TES) systems would enable NPPs to respond nimbly to market variability and could also position advanced NPPs to participate differently in restructured markets, thus further enhancing their economic competitiveness. TES systems could also benefit the electric grid by eliminating the need for peaking plants, as well as by improving the economic performance of baseload NPPs. While TES technologies afford a unique opportunity to address many of these challenges, the applicability of these systems is also complicated by the fact that various advanced NPPs are designed differently, each with its own temperature range, size, operating fluids, and operating conditions. Hence, TES systems face significant barriers to investment, as more information on their compatibility and performance metrics is needed to quantify the advantages provided by each, as well as the challenges these technologies might face if coupled with a particular type of advanced NPP. This study explores the possibility of integrating a wide variety of TES technologies with various categories of advanced NPPs, based on their operating characteristics. To help decision makers, users and developers decide which TES technology is best suited to a particular category of advanced NPPs, this research present a Phenomena Identification and Ranking Table (PIRT) analysis of 10 TES systems that could potentially be coupled with advanced NPPs, which themselves are divided into nine categories based on their operating conditions. Each advanced NPP category is evaluated for compatibility with the 10 TES systems by assembling and discussing a database of information concerning 10 engineering questions, defined herein in as figures of merit (FOMs), such as: technology readiness level (TRL), temperature compatibility, energy density, size, cycle frequency , ramp time, realignment frequency, geographic needs, environmental impact, and interventions. By assembling a database of information concerning the TES technologies' compatibility with various advanced NPP systems, this study can help developers acquaint themselves with a particular TES technology before choosing to build a new integrated installation.
... Combining nuclear reactors with TES systems for enhanced flexibility and to increase revenues has been previously investigated in several studies [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. For example, Carlson et al. [6] investigated the impact of integrating a pressurised water nuclear reactor (AP1000) with TES tanks. ...
... This additional power can be supplied to the electricity grid during high demand to increase revenues. Other TES systems including molten-salt tanks [5,9], firebrick resistance-heated energy system [10] and geothermal heat storage [11] were also considered and discussed. ...
Nuclear power plants are commonly operated as baseload units due to their low variable costs, high investment costs and limited ability to modulate their output. The increasing penetration of intermittent renewable power will require additional flexibility from conventional generation units, in order to follow the fluctuating renewable output while guaranteeing security of energy supply. In this context, coupling nuclear reactors with thermal energy storage could ensure a more continuous and efficient operation of nuclear power plants, while at other times allowing their operation to become more flexible and cost-effective. This study considers options for upgrading a 1610-MWel nuclear power plant with the addition of a thermal energy storage system and secondary power generators. This configuration allows the plant to generate up to 2130 MWel during peak load, representing an increase of 32% in nominal rated power. The total whole-system benefits of operating the proposed configuration are quantified for several scenarios in the context of the UK's national electricity system. Replacing conventional with flexible nuclear plants is found to generate system cost savings between £24.3m/yr and £88.9m/yr, with the highest benefit achieved when stored heat is fully discharged in 0.5 h. At an estimated cost of added flexibility of £42.7m/yr, the proposed flexibility upgrade to such a nuclear power plant appears to be economically justified for a wide range of low-carbon scenarios, provided that the number of flexible nuclear plants in the system is small.
... Here we consider TES for nuclear power plants as a means to provide baseload flexibility and more favorable economics, and thus to help decarbonize electricity production [15,16], which is a leading source of direct carbon-dioxide emissions [17]. Figure 1 illustrates operation of a nuclear power plant with TES. ...
Thermal energy storage (TES) coupled with nuclear energy could be a transformative contribution to address the mismatch in energy production and demand that occur with the expanding use of solar and wind energy. TES can generate new revenue for the nuclear plant and help decarbonize the electricity grid. Prior work by the authors identified two technical approaches to interface TES with nuclear. One, termed the primary cycle TES, charges and discharges the TES within the main Rankine power cycle. The second, termed the secondary cycle TES or SCTES, discharges the TES to a secondary power cycle. The present work analyzes the potential economic benefits of TES in an arbitrage market for a 1050 MWe nuclear plant. The study is the first to provide a realistic quantification of the impacts of changes in capacity factor due to use of TES on revenue and internal rate of return (IRR). The analysis is for a three-year period for peaking powers from 120% to 150% of the conventional nuclear plant for an exemplary deregulated utility represented by the Electric Reliability Council of Texas (ERCOT). The SCTES consistently provides the highest revenue and IRR. The benefits increase with increasing use of TES and variability of electricity prices. The results provide a technically sound understanding of the effects of how TES is integrated with nuclear power on economics and strong economic support for pursuing design and implementation of the SCTES.
... The coupling of nuclear reactors with TES systems for the purpose of improving flexibility and increasing revenues has been proposed and studied previously [27][28][29][30][31][32][33][34][35][36][37][38][39][40] . For example, Carlson et al. [27] studied the impact of integrating a TES tank within a primary power generation Rankine cycle in a modern nuclear reactor. ...
Electricity markets are fast changing because of the increasing penetration of intermittent renewable generation, leading to a growing need for the flexible operation of power plants to provide regulation services to the grid. Previous studies have suggested that conventional power plants (e.g., nuclear) may benefit from the integration of thermal energy storage (TES), as this enables greater flexibility. In conventional Rankine-cycle power plants, steam can be extracted during off-peak periods to charge TES tanks filled with phase-change materials (PCMs); at a later time, when this is required and/or economically favourable, these tanks can feed secondary thermal power plants to generate power, for example, by acting as evaporators of organic Rankine cycle (ORC) plants. This solution offers greater flexibility than TES-only solutions that store thermal energy and then release this back to the base power plant, as it allows both derating and over-generation. The solution is applied here to a specific case study of a 670 MW el nuclear power plant in the UK, which is a typical baseload power plant not intended for flexible operation. It is found a maximum combined power of 822 MW el can be delivered during peak demand, which is 23% higher than the base plant's (nominal) rated power, and a maximum derating of 40%, i.e., down to 406 MW el during off-peak demand. An operational energy management strategy (EMS) is then proposed for optimising the charging of the TES tanks during off-peak demand periods and for controlling the discharging of the tanks for electricity generation during peak-demand periods. An economic analysis is performed to evaluate the potential benefits of this EMS. Profitability in the case study considered here can result when the average peak and off-peak electricity price variations are at least double those that occurred in the UK market in 2019 (with recent data now close to this), and when TES charge/discharge cycles are performed more than once per day with a discharge duration to the ORC plants longer than 2 h. When considering the most recent UK electricity prices in 2021 (to-date), the EMS investment cost for one 1-h charge and 1-h discharge cycle per day is 199 m£ with a total generation of 50 GWh per year and a levelised cost of electricity (LCOE) of 463 £/MWh. The investment cost drops significantly to 48 m£ when discharging for a longer duration of 8 h as the size of the ORC plants decrease. The projected LCOE also decreases to 159 £/MWh when doubling the total generated electricity (100 GWh/year) by employing two 8-h TES charge/discharge cycles per day. Importantly, it is found that the economics of the EMS are determined by a trade-off between longer discharge durations to the ORC plants that minimises their size and cost, and shorter charge/discharge durations that yield the highest spread between off-peak and peak electricity prices.
