Session: 05-09 Particles for Thermal Storage in CSP 2

Paper Number: 115296

115296 - Development of a Particle-Based Thermal Battery Using Pumped Thermal Energy Storage 

Increasing renewable energy penetration in electric grid and broad decarbonization of industrial sectors require energy storage at various scales to provide reliable carbon-free energy supply. Long-duration energy storage (LDES, 10-100 hours) can improve the dispatchability and grid reliability with increasing levels of renewable power supply. Thermal energy storage (TES) has siting flexibility and the ability to store a large capacity of energy, and thus has the potential to meet LDES needs and provide charging and discharging durations beyond the economic capacity of electrochemical batteries. TES technology has evolved from concentrating solar power (CSP) generation and is recognized as an economic large-scale energy storage method. A standalone electric-thermal energy storage system supporting renewable integration of wind and solar photovoltaics performs as a thermal battery in large capacity and LDES applications and can firm renewable generation and boost overall grid resilience and security.

A novel Pumped Thermal Electricity Storage (PTES) system that uses low-cost solid particles as the storage media and direct air/particle contract fluidized bed heat exchangers for charge/discharge processes has shown significant potentials in achieving high storage cycle efficiency for LDES applications. Solid particle storge media provides wider operating temperature ranges and able to store both hot and cold energy enables a simplified system configuration compared to PTES using liquid thermal storage. This arrangement confers several advantages compared to a state-of-the-art PTES system using molten-nitrate salt for hot storage and organic liquid for cold storage.  The presentation will describe the system layout and discuss development progress.

The impact of parameters such as approach temperatures, pressure losses, and cycle temperatures on the round-trip efficiency, work ratio, and heat-to-work ratio have been explored using thermodynamic models, and results indicate that electrical storage roundtrip efficiency can exceed 55%. Cycle operating conditions were defined according to turbomachinery specifications, and key system components were conceptually designed and modeled for their performance. Laboratory-scale prototype of fluidized bed heat exchanger is under fabrication and to be tested to verify the component design approaches and operations at conditions relevant to the modeling efforts and product designs. The development addresses key component risks including: (1) realizing low air/particle approach temperature in the pressurized fluidized bed heat exchanger, (2) dehumidification measures to enable particles to be used for cold storage, and (3) integrating PTES reversible turbomachinery. To this end, we have developed modeling tools to investigate PTES cycles, system configurations, and key component designs for particle-based systems. This presentation will present thermodynamic models, selection of cycle operating conditions for the particle-PTES system, and progress on design, modeling, and lab-scale testing of key components.

Presenting Author: Jeffrey Gifford National Renewable Energy Laboratory

Presenting Author Biography: Jeff works at NREL as a contingent work when he is working towards his Ph.D. degree at Colorado School of Mines in an Advanced Energy Study program with NREL.