Falling particle receivers are a promising receiver design to couple with particle-based concentrating solar power to help meet future levelized cost of electricity targets in next generation systems. The thermal performance of receivers is critical to the economics of the overall system, and accurate models of particle receivers are necessary to predict the performance in all conditions. A model validation study was performed using falling particle receiver data recently collected at the National Solar Thermal Test Facility at Sandia National Laboratories. The particle outlet temperature, the thermal efficiency of the receiver, and the wind speed and direction around the receiver were measured in 26 steady-state experiments and compared to a corresponding receiver model. The results of this study showed improved agreement with the experimental data over past validation efforts but did not fully meet all predefined validation metrics. Future model improvements were identified to continue to strengthen the modeling capabilities.
The need for reliable, cost-effective, utility scale energy storage that is universally applicable across different regions is becoming evident with the global transition towards non-polluting renewable energy resources. The operations and management of these energy storage technologies introduces a unique challenge that is inherently different from the conventional energy storage in the form of fossil fuel. The investigation into the business model, value proposition and economic viability of a utility scale thermal energy storage was part of a program sponsored by the United States Department of Energy, called Energy I-Corps. During this program, the project team reached out to a series of industry stakeholders to conduct interviews on the topic of thermal energy storage for utility scale power generation. Specific focus was placed on the business model based on the market needs in the context of the power grid in the United States. The utilization and re-use of infrastructure at existing thermo-electric power plants yielded the most viable business model for the implementation of the form of thermal energy storage discussed here.
A significant amount of uncertainty exists regarding potential human exposure to laboratory biomaterials and organisms in Biosafety Level 2 (BSL-2) research laboratories. Computational fluid dynamics (CFD) modeling is proposed as a way to better understand potential impacts of different combinations of biomaterials, laboratory manipulations, and exposure routes on risks to laboratory workers. Here, in this study, we use CFD models to simulate airborne concentrations of contaminants in an actual BSL-2 laboratory under different configurations. Results show that ventilation configuration, sampling location, and contaminant source location can significantly impact airborne concentrations and exposures. Depending on the source location and airflow patterns, the transient and time-integrated concentrations varied by several orders of magnitude. Contaminant plumes from sources located near a return vent (or exhaust like a fume hood or ventilated biosafety cabinet) are likely to be more contained than sources that are further from the exhaust. Having a direct flow between the source and the exhaust (through-flow condition) may reduce potential exposures to individuals outside the air flow path. Designing a BSL-2 room with ventilation and airflow patterns that maximize through-flow conditions to the return/exhaust vents and minimize dispersion and mixing throughout the room is, therefore, recommended. CFD simulations can also be used to assist in characterizing the impacts of supply and return vent locations, room layout, and source locations on spatial and temporal contaminant concentrations. In addition, proper placement of particle sensors can also be informed by CFD simulations to provide additional characterization and monitoring of potential exposures in BSL-2 facilities.
Cement production for concrete has been responsible for ~7–8% of global greenhouse gas (GHG) emissions, and nearly equally contribution for steel production processes (EPA, 2020). In order to achieve carbon neutrality by 2050, a novel solution has to be investigated. This project aims to develop fundamental mechanistic understanding and experimental characterization to create a 3D printable biopolymer concrete using plant-based polyurethane as an innovative and sustainable alternative for Portland cement concrete, with significantly low carbon footprint. Future construction will utilize the advances in digital additive manufacturing (3D printing) to produce optimal geometries with a minimum waste of materials. Understanding the polymerization process, factors impacting the composite rheology, and the structural behavior of this biopolymer concrete will enable us to engineer the next generation of concrete structures with low carbon footprint. This project aims to improve the nation’s ability to control Greenhouse Gas emission neutrality for the set goal of 2050 via introducing a structurally viable bio-based polymer concrete.
This report documents the results and conclusions of a recent project to understand the technoeconomics of utility-scale, particle-based concentrating solar power (CSP) facilities leveraging unique operational strategies. This project included two primary objectives. The first project objective was to build confidence in the modeling approaches applied to falling particle receivers (FPRs) including the effect s of wind. The second project objective was to create the necessary modeling capability to adequately predict and maximize the annual performance of utility-scale, particle-based CSP plants under anticipated conditions with and without active heliostat control. Results of an extensive model validation study provided the strongest evidence to date for the modeling strategies typically applied to FPRs, albeit at smaller receiver scales. This modeling strategy was then applied in a parametric study of candidate utility-scale FPRs, including both free-falling and multistage FPR concepts, to develop reduced order models for predicting the receiver thermal efficiency under anticipated environmental and operating conditions. Multistage FPRs were found to significantly improve receiver performance at utility-scales. These reduced order models were then leveraged in a sophisticated technoeconomic analysis to optimize utility-scale , particle-based CSP plants considering the potential of active heliostat control. In summary, active heliostat control did not show significant performance benefits to future utility-scale CSP systems though some benefit may still be realized in FPR designs with wide acceptance angles and/or with lower concentration ratios. Using the latest FPR technologies available, the levelized-cost of electricity was quantified for particle-based CSP facilities with nominal powers ranging from 5 MWe up to 100 MWe with many viable designs having costs < 0.06 $/kWh and local minimums occurring between ~25–35 MWe.
This report summarizes the needs, challenges, and opportunities associated with carbon-free energy and energy storage for manufacturing and industrial decarbonization. Energy needs and challenges for different manufacturing and industrial sectors (e.g., cement/steel production, chemicals, materials synthesis) are identified. Key issues for industry include the need for large, continuous on-site capacity (tens to hundreds of megawatts), compatibility with existing infrastructure, cost, and safety. Energy storage technologies that can potentially address these needs, which include electrochemical, thermal, and chemical energy storage, are presented along with key challenges, gaps, and integration issues. Analysis tools to value energy storage technologies in the context of manufacturing and industrial decarbonizations are also presented. Material is drawn from the Energy Storage for Manufacturing and Industrial Decarbonization (Energy StorM) Workshop, held February 8 - 9, 2022. The objective was to identify research opportunities and needs for the U.S. Department of Energy as part of its Energy Storage Grand Challenge program.
Particle heat exchangers are a critical enabling technology for next generation concentrating solar power (CSP) plants that use supercritical carbon dioxide (sCO2) as a working fluid. This report covers the design, manufacturing and testing of a prototype particle-to-sCO2 heat exchanger targeting thermal performance levels required to meet commercial scale cost targets. In addition, the the design and assembly of integrated particle and sCO2 flow loops for heat exchanger performance testing are detailed. The prototype heat exchanger was tested to particle inlet temperatures of 500 °C at 17 MPa which resulted in overall heat transfer coefficients of approximately 300 W/m2-K at the design point and cases using high approach temperature with peak values as high as 400 W/m2-K
The National Solar Thermal Test Facility (NSTTF) at Sandia National Laboratories New Mexico (SNL/NM) developed this Life Cycle Management Plan (LCMP) to document its process for executing, monitoring, controlling and closing-out Phase 3 of the Gen 3 Particle Pilot Plant (G3P3). This plan serves as a resource for stakeholders who wish to be knowledgeable of project objectives and how they will be accomplished.
Falling particle receivers are an emerging technology for use in concentrating solar power systems. In this study, quartz half-shells are investigated for use as full or partial aperture covers to reduce receiver thermal losses. Quartz half-shell aperture covers offer the ability to minimally interfere with incoming solar radiation from the heliostat field while obstructing thermal radiation and advection from leaving the receiver cavity. The fluid dynamics and heat transfer of a receiver subdomain and surrounding air are modeled using ANSYS® FLUENT. We compare the percentage of total incident solar power lost due to conduction through the receiver walls, advective losses through the aperture, and radiation exiting the aperture. Contrary to expected outcomes, results show that quartz aperture covers can increase radiative losses and result in modest to nonexistent reductions in advective losses. The increased radiative losses are driven by elevated quartz half-shell temperatures and have the potential to be mitigated by active cooling and/or material selection. Quartz half-shell total transmissivity was measured experimentally using a radiometer and the National Solar Thermal Test Facility heliostat field with values up to 0.97 ± 0.01. Quartz half-shell aperture covers did not yield expected efficiency gains in numerical results due to increased radiative losses, but efficiency improvement in some numerical results and the performance of quartz half-shells subject to concentrated solar radiation suggest that quartz half-shell aperture covers should be investigated further.
This paper summarizes the evolution of the Gen 3 Particle Pilot Plant (G3P3) receiver design with the goal of reducing heat losses and increasing thermal efficiencies. New features that were investigated included aperture covers and shrouds, active airflow, multistage catch-and-release devices (stairs), and optimization of receiver cavity geometry. Simulations and ground-based testing showed that a reduced receiver volume and aperture shroud could reduce advective heat losses by ∼40 - 50%, and stairs could increase opacity and reduce backwall temperatures. The reduced volume receiver and stairs were selected for on-sun testing, and receiver efficiencies up to 80 - 90% were achieved in the current test campaign. The receiver thermal efficiency generally increased as a function of incident power and particle mass flow rates. In addition, particle outlet temperatures were maintained to within ±10 °C of a prescribed setpoint temperature up to ∼700 °C using a PID controller that adjusted the particle mass flow rate into the receiver in response to the measured particle outlet temperatures.
Particle-based heat transfer materials used in concentrating solar power systems benefit from gravity-fed arrangements such as vertically integrated components inside the receiver tower which can eliminate the need for conveyance machinery. However, the amount of particles required for commercial scale systems near 100 MWe can require towers with very thick walls that must be built with high-strength concrete. Cost models for particle-based receiver towers with internal particle storage are being developed in this work and compared to well-established cost models that have been used to estimate tower costs for molten salt systems with external storage tanks. New cost models were developed to accommodate the high-temperature applications required for CSP. Further research is needed to directly compare costs between tower-integrated and external storage. For now, a method is proposed to superimpose increased storage costs with existing molten salt CSP towers. For instances where suitable materials are unavailable or do not meet the structural requirements, ground based storage bins must be used in concert with mechanical conveyance systems. Ground based storage vessels have been shown to be consistent with low thermal energy storage cost and heat loss goals. Ground based storage vessels are well-established in industry.