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At least 289 records · Page 16

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DOE OSTI2024

Component Criticality in BESS for Cybersecurity

Battery energy storage systems (BESS), inverters, and associated digital equipment are integral pieces of interdependent energy delivery systems. When considering the supply chain security of such systems, there is often a misplaced focus on the origin of energy generation and storage materials like battery cells, overlooking the more significant cyber risks that stem from digital power electronics control systems. Part of this misplaced focus is due to the relative costs of these components, with more attention given to expensive raw materials rather than the impactful digital elements themselves. The Idaho National Laboratory (INL) is addressing this gap in supply chain security through a systems-of-systems approach that considers the impact various components in digital energy systems can have should misoperation occur. Therefore, INL assigns a cyber criticality score based on quantitative analysis, which enables informed prioritization of mitigations and allows operators to reduce risk in light of the prevalence of a BESS and associated systems foreign supply chain.

25 ENERGY STORAGE↗

DOE OSTI2025

A Modelica Implementation of an Organic Rankine Cycle

Organic Rankine cycle (ORC) systems generate power from low-grade heat sources, such as geothermal sources and industrial waste heat. A key feature is that a working fluid is selected to match the temperature of the source. With the vast pool of candidate working fluids comes the challenge of developing a large number of robust thermodynamic media models. We implemented a subcritical ORC model in Modelica that uses working fluid data records and interpolation schemes in lieu of thermodynamic medium evaluation for energy recovery estimation. This is a component model that can be integrated into a larger energy system model. It does not require detailed thermodynamic, heat transfer, or machine analysis. Our ORC model fills a gap where working fluids are ready to choose or easy to add, and at the same time can be integrated into an energy system.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

DOE OSTI2025

Calculating Critical Inertia of a Power System

The increasing integration of renewable energy sources in modern power systems has led to a decline in system inertia, raising concerns about frequency stability following large disturbances. Determining critical inertia is essential to prevent excessive frequency decline and ensure grid stability. This paper evaluates four different methods for calculating critical inertia, using the Electric Reliability Council of Texas (ERCOT) system as a test case. The results highlight the importance of employing multiple methodologies to capture the full spectrum of inertia requirements.

Hakim sneha, Fariha [University of Tennessee, Knox↗

NASA NTRS2000

Application of Energy Integration Techniques to the Design of Advanced Life Support Systems

Exchanging heat between hot and cold streams within an advanced life support system can save energy. This savings will reduce the equivalent system mass (ESM) of the system. Different system configurations are examined under steady-state conditions for various percentages of food growth and waste treatment. The scenarios investigated represent possible design options for a Mars reference mission. Reference mission definitions are drawn from the ALSS Modeling and Analysis Reference Missions Document, which includes definitions for space station evolution, Mars landers, and a Mars base. For each scenario, streams requiring heating or cooling are identified and characterized by mass flow, supply and target temperatures and heat capacities. The Pinch Technique is applied to identify good matches for energy exchange between the hot and cold streams and to calculate the minimum external heating and cooling requirements for the system. For each pair of hot and cold streams that are matched, there will be a reduction in the amount of external heating and cooling required, and the original heating and cooling equipment will be replaced with a heat exchanger. The net cost savings can be either positive or negative for each stream pairing, and the priority for implementing each pairing can be ranked according to its potential cost savings. Using the Pinch technique, a complete system heat exchange network is developed and heat exchangers are sized to allow for calculation of ESM. The energy-integrated design typically has a lower total ESM than the original design with no energy integration. A comparison of ESM savings in each of the scenarios is made to direct future Pinch Analysis efforts.

Levri, Julie↗

DOE OSTI2026

Structural dynamics of the renewable energy economy: A longitudinal input-output insights for a resilient transition

As countries accelerate their energy transitions, understanding how renewable energy (RE) systems structurally integrate into national economies is essential. This study presents a longitudinal economic input-output (EIO) analysis of the renewable energy sector in South Korea from 2016 to 2022. We develop a novel EIO-based framework that disaggregates the RE sector both by energy source (thermal, hydro, nuclear and renewable) and by industrial function (manufacturing, generation, and services), allowing for a detailed assessment of production dynamics, value-added creation, and import dependency. By quantifying backward and forward linkages and induced economic effects, the analysis reveals persistent structural vulnerabilities in renewable manufacturing and increasing sectoral interdependencies. Results reveal that while the renewable energy sector's production and value-added shares have increased, critical segments remain highly import-dependent, particularly in equipment manufacturing. The analysis highlights systemic gaps in domestic supply chain resilience and offers sector-specific insights for reducing vulnerability and enhancing energy security. Although applied to South Korea as a case study, the proposed framework is designed to be transferable to other national contexts where renewable energy planning requires economic structural insights. The findings offer policy-relevant guidance for enhancing domestic energy resilience and aligning industrial strategy with long-term decarbonization goals.

Economic linkage↗

NASA NTRS1985

Wheel configurations for combined energy storage and attitude control systems

Integrated power and attitude control system (IPACS) studies performed over a decade ago established the feasibility of simultaneously storing electrical energy in wheels and utilizing the resulting momentum for spacecraft attitude control. It was shown that such a system possessed many advantages over other contemporary energy storage and attitude control systems in many applications. More recent technology advances in composite rotors, magnetic bearings, and power control electronics have triggered new optimism regarding the feasibility and merits of such a system. This paper presents the results of a recent study whose focus was to define an advanced IPACS and to evaluate its merits for the Space Station application. Emphasis is given to the selection of the wheel configuration to perform the combined functions. A component design concept is developed to establish the system performance capability. A system-level trade study, including life-cycle costing, is performed to define the merits of the system relative to two other candidate systems. It is concluded that an advanced IPACS concept is not only feasible but offers substantial savings in mass and life-cycle cost.

Oglevie, R. E.↗

DOE OSTI2025

A dynamic 2D Borehole Thermal Energy Storage (BTES) model for enhanced computational efficiency

Progressing toward a future increasingly reliant on renewable energy sources, the development of effective, durable energy storage solutions becomes essential to balance supply and demand fluctuations. Borehole Thermal Energy Storage (BTES) is a long-duration thermal energy storage technology that captures excess heat generated from renewable energy sources and stores it underground for later use, enabling the efficient utilization of sustainable energy. This approach is particularly valuable in district energy networks when integrated with Ground Source Heat Pumps (GSHP) to provide stable heating and cooling. However, traditional three-dimensional (3D) numerical models of BTES systems demand extensive computational resources, limiting their practicality for real-time and large-scale applications. This study introduces a novel two-dimensional (2D) modeling approach that reduces computational costs while maintaining high accuracy. By employing a radial ring-based discretization method, the model simulates heat injection, retention, and retrieval dynamics over seasonal cycles. A new thermal-mass weighted-average temperature parameter is introduced to evaluate the performance of BTES systems. Model validation against FEFLOW simulations demonstrates a 17-fold improvement in computational speed compared to traditional Computational Fluid Dynamics (CFD) models while achieving a mean absolute percentage error (MAPE) of 2 % during charging and 4 % during discharging. Additionally, a trade-off analysis between computational efficiency and accuracy is conducted, ensuring the model's applicability for real-world scenarios. The findings of this research contribute to the development of computationally efficient BTES models, facilitating better optimization, control, and integration into renewable energy systems. This work provides a foundation for further studies in techno-economic analysis, multi-year performance evaluation, and real-time operational strategies for BTES applications, supporting a more sustainable energy future.

2D modeling↗

NASA NTRS1977

Magnetic bearing momentum wheels with magnetic gimballing capability for 3-axis active attitude control and energy storage

A 3-axis active attitude control system with only one rotating part was developed using a momentum wheel with magnetic gimballing capability as a torque actuator for all three body axes. A brief description of magnetic bearing technology is given. It is concluded that based on this technology an integrated energy storage/attitude control system with one air of counterrotating rings could reduce the complexity and weight of conventional systems.

Sindlinger, R. S.↗

NASA NTRS1984

Engineering model system study for a regenerative fuel cell: Study report

Key design issues of the regenerative fuel cell system concept were studied and a design definition of an alkaline electrolyte based engineering model system or low Earth orbit missions was completed. Definition of key design issues for a regenerative fuel cell system include gaseous reactant storage, shared heat exchangers and high pressure pumps. A power flow diagram for the 75 kW initial space station and the impact of different regenerative fuel cell modular sizes on the total 5 year to orbit weight and volume are determined. System characteristics, an isometric drawing, component sizes and mass and energy balances are determined for the 10 kW engineering model system. An open loop regenerative fuel cell concept is considered for integration of the energy storage system with the life support system of the space station. Technical problems and their solutions, pacing technologies and required developments and demonstrations for the regenerative fuel cell system are defined.

Chang, B. J.↗

DOE OSTI2024

CloudZero Phase 2 Technical Report

Expand upon the successful Phase 1 net zero cloud test proof of concept by moving actual OT systems to the cloud and proving cloud feasibility to support various OT technologies such as IoT, Machine Learning, etc. Explore threat analysis when these technologies are moved to the cloud. A detailed analysis in NREL ARIES Cyber Range will be used to conduct deeper analysis of cloud suitability to support OT and net zero system operations in a higher fidelity representative environment. Outputs will identify, quantify, and document the results and cyber security risks associated with the move of these OT technologies in a formal delivered report. Programmatic Benefits: Identify cloud integration challenges for energy systems characterize the cloud threat space, contribute to policy and standards discussions, empower the sector to change their cloud culture where appropriate.

24 POWER TRANSMISSION AND DISTRIBUTION↗

NASA NTRS1992

Energy loss analysis of an integrated space power distribution system

The results of studies related to conceptual topologies of an integrated utility-like space power system are described. The system topologies are comparatively analyzed by considering their transmission energy losses as functions of mainly distribution voltage level and load composition. The analysis is expedited by use of a Distribution System Analysis and Simulation (DSAS) software. This recently developed computer program by the Electric Power Research Institute (EPRI) uses improved load models to solve the power flow within the system. However, present shortcomings of the software with regard to space applications, and incompletely defined characteristics of a space power system make the results applicable to only the fundamental trends of energy losses of the topologies studied. Accountability, such as included, for the effects of the various parameters on the system performance can constitute part of a planning tool for a space power distribution system.

Kankam, M. David↗

NASA NTRS1992

Energy loss analysis of an integrated space power distribution system

Kankam, M. D.↗

NASA NTRS1985

Total energy based flight control system

An integrated aircraft longitudinal flight control system uses a generalized thrust and elevator command computation (38), which accepts flight path angle, longitudinal acceleration command signals, along with associated feedback signals, to form energy rate error (20) and energy rate distribution error (18) signals. The engine thrust command is developed (22) as a function of the energy rate distribution error and the elevator position command is developed (26) as a function of the energy distribution error. For any vertical flight path and speed mode the outerloop errors are normalized (30, 34) to produce flight path angle and longitudinal acceleration commands. The system provides decoupled flight path and speed control for all control modes previously provided by the longitudinal autopilot, autothrottle and flight management systems.

Lambregts, Antonius A.↗

NASA NTRS2017

Design and testing of high-performance mini-channel graphite heat exchangers in thermoelectric energy recovery systems

Recent national energy usage studies by Lawrence Livermore National Laboratory in 2015 [1] show that there is approximately 59 Quads (1015 Btu’s) of waste thermal energy throughout various industrial, residential, power generation, and transportation sectors of the U.S. economy. Thermoelectric energy recovery is one important technology for recovering this waste thermal energy in high-temperature industrial, transportation and military energy systems. Thermoelectric generator (TEG) systems in these applications require high performance hot-side and cold-side heat exchangers to provide the critical temperature differential and transfer the required thermal energy. High performance hot-side heat exchangers in these systems are often metal-based due to requirements for high-temperature operation, strength at temperature, corrosion resistance, and chemical stability. However, the generally selected metal-based hot-side heat exchangers (i.e., Inconels, Stainless Steels) suffer from low thermal conductivity, high thermal expansion, and high density, which degrades their thermal performance, leads to high thermal-expansion-driven stresses, and creates relatively high mass/high volume (i.e., low power density) TEG systems that are then difficult to fabricate and integrate into viable energy recovery systems. This paper describes the design and testing of a new, high-temperature minichannel graphite heat exchanger designed for operation up to 500C that is a critical element of a high-power-density TEG power system for aircraft energy recovery. This high-performance graphite heat exchanger represents a new state-of-the-art standard in high-temperature heat exchangers for TEG systems, which provides higher thermal transport, less thermal expansion at operation, lower system level stresses on TE components, and a lighter weight TEG system. This new heat exchanger creates a new design paradigm in TEG system design for terrestrial energy recovery and potential NASA technology infusion into terrestrial energy system applications. This paper will present and discuss the key heat transfer, pressure drop, pumping power analyses and design tradeoffs that created this unique design. Heat transfer and pressure drop modeling was performed with both empirical models based on known heat transfer and friction factor correlations and COMSOL thermal/fluid dynamic modeling of the graphite heat exchanger structure. We will also discuss resulting thermal transport and heat fluxes predicted at the TEG interface level. Heat exchanger performance testing was performed under simulated operating conditions and correlation with test data at the anticipated operating temperature conditions will be presented and discussed.

Shevade, Abhijit↗

DOE OSTI2025

Optimizing Control for Efficient Load Shifting with Thermal Energy Storage in Existing HVAC Systems

This project developed the integration of a direct-contact heat exchanger (DCHX) based thermal energy storage (TES) system with a chiller–air handling unit (AHU) plant to evaluate its potential for reducing building energy costs. Detailed physical models of the TES unit, building envelope, and HVAC components were developed alongside simplified control-oriented models to support both high-fidelity simulation and real-time optimization. Two control strategies were implemented and compared: a rule-based control (RBC) aligned with utility time-of-use (ToU) rates, and a model predictive control (MPC) framework leveraging forecasts of building load, weather, and internal gains.Simulation results show that the RBC strategy reduced daily electricity costs by around 30% by shifting cooling production from on-peak to off-peak hours. In contrast, the MPC strategy achieved significantly greater performance, reducing daily operating costs by up to 44% and peak-hour costs by more than 60%. Both strategies maintained indoor thermal comfort within acceptable limits, with MPC further improving load distribution and reducing equipment cycling.The outcomes confirm that TES integration, particularly when coordinated with advanced predictive control, can provide substantial cost savings and on-peak demand reduction. . These findings directly support the U.S. Department of Energy’s goals for grid-interactive efficient buildings and demonstrate the potential of TES-enabled HVAC systems for scalable deployment across the commercial building.

99 GENERAL AND MISCELLANEOUS↗

DOE OSTI2025

Optimizing Control for Efficient Load Shifting with Thermal Energy Storage in Existing HVAC Systems

This project developed the integration of a direct-contact heat exchanger (DCHX) based thermal energy storage (TES) system with a chiller–air handling unit (AHU) plant to evaluate its potential for reducing building energy costs. Detailed physical models of the TES unit, building envelope, and HVAC components were developed alongside simplified control-oriented models to support both high-fidelity simulation and real-time optimization. Two control strategies were implemented and compared: a rule-based control (RBC) aligned with utility time-of-use (ToU) rates, and a model predictive control (MPC) framework leveraging forecasts of building load, weather, and internal gains. Simulation results show that the RBC strategy reduced daily electricity costs by around 30% by shifting cooling production from on-peak to off-peak hours. In contrast, the MPC strategy achieved significantly greater performance, reducing daily operating costs by up to 44% and peak-hour costs by more than 60%. Both strategies maintained indoor thermal comfort within acceptable limits, with MPC further improving load distribution and reducing equipment cycling. The outcomes confirm that TES integration, particularly when coordinated with advanced predictive control, can provide substantial cost savings and on-peak demand reduction. . These findings directly support the U.S. Department of Energy’s goals for grid-interactive efficient buildings and demonstrate the potential of TES-enabled HVAC systems for scalable deployment across the commercial building.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2025

Impact of shading following installation of agrivoltaic systems on eco-physiological and biochemical attributes of “Howes” cranberry in Massachusetts

Agrivoltaic (AV) systems, which integrate solar energy generation with crop production on the same piece of land, offer a sustainable solution for optimizing land-use efficiency. However, the impact of shading induced by solar panels on crop growth, physiology, and metabolic activities of cranberry is not known. Understanding these interactions is essential for assessing the feasibility of AV systems in cranberry production. In this study we evaluated eco-physiological and biochemical crop responses on a commercial ‘Howes’ cranberry bog grown under an agrivoltaics system using different row spacings in the year immediately following installation. Following installation of fixed tilt solar panels at a height of 3.0 m above the plant canopy, four shading treatments were evaluated: an uncovered control area and row spacings of 9.0 m, 7.0 m, and 5.0 m, corresponding to 30%, 35%, and 37% shading respectively. The shading effect was also evaluated at three different fruit developmental stages (green, blush, and full-red stage). Using microclimate sensors installed in the treatment areas, key eco-physiological and biochemical parameters, including leaf gas exchange, chlorophyll, anthocyanin, and antioxidant content, electrolyte leakage, proline and trehalose accumulation, were assessed. While moderate shading (30% and 35%) alleviated environmental stress, as reflected by improved leaf water status and reduced electrolyte leakage, these same treatments suppressed key physiological and metabolic functions, including photosynthetic activity, carbon reserve accumulation, and the biosynthesis of stress-related osmolytes and antioxidant compounds. Under higher shading (37%), these reductions were even more pronounced, indicating a potential threshold beyond which the benefits of shading are outweighed by declines in assimilate production and secondary metabolism. These findings highlight a trade-off between the stress-mitigating benefits of shading and the alterations in key physiological and metabolic processes under agrivoltaic systems. Minimizing these trade-offs by optimizing row spacing in agrivoltaics systems is critical to maintain cranberry physiological status. Since commercial cranberry is grown as a continuous plant canopy (no interrow spaces for equipment travel), damage caused by the installation process likely impacted crop response evaluated in the first year; multi-year studies are needed to fully understand the dynamics of a dual-use system. Notably, this work provides the first direct measurements of proline, trehalose content, and electrolyte leakage in cranberry grown under AV conditions, offering new insight into their physiological adjustments to shading.

14 SOLAR ENERGY↗

NASA NTRS1980

Solar space heating for the Visitors Center, Stephens College, Columbia, Missouri

The solar energy system located at the Visitors' Center on the Stephens College Campus, Columbia, Missouri is discussed. The system is installed in a four-story, 15,000 square foot building. The solar energy system is an integral design of the building and utilizes 176 hydronic flat plate collectors which use a 50 percent water ethylene blycol solution and water-to-water heat exchanger. Solar heated water is stored in a 5,000 gallon water storage tank located in the basement equipment room. A natural gas fired hot water boiler supplies hot water when the solar energy heat supply fails to meet the demand. The designed solar contribution is 71 percent of the heating load.

Source record↗