Session: 06-01: Thermal Energy Storage

Paper Number: 131141

131141 - System and Component Development of Particle-Based Pumped Thermal Energy Storage 

Abstract: 

Broad decarbonization using renewable energy requires energy storage at various scales to provide reliable carbon-free energy supply. Long-duration energy storage (LDES, 10-100 hours) can improve dispatchability and grid reliability with increasing levels of renewable power supply. Thermal energy storage (TES) can be flexibly sited and can store large capacities of energy, and thus has the potential to meet the need for LDES and provide charging and discharging durations beyond the economic capacity of conventional batteries. TES technology has evolved from concentrating solar power (CSP) systems and is recognized as an economically feasible large-scale energy storage method. A standalone electric-thermal energy storage system supporting renewable integration of wind and solar power without CSP field can firm renewable generation and boost overall grid resilience and security.

A novel Pumped Thermal Energy Storage (PTES) system that uses solid particles as storage media and fluidized bed heat exchangers in charge/discharge processes has shown significant potential in achieving high performance and low cost for LDES. 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. Solid particle storge media provides wider operating temperature ranges and enables a simplified system configuration compared to PTES using liquid thermal storage. To this end, we have developed modeling tools to investigate PTES cycles, system configurations, and key component designs.

The development of particle-based PTES has considered optimum cycle performance that shows greater than 55% storage roundtrip efficiency based on thermodynamic cycle modeling. The cycle operating conditions were defined according to turbomachinery design approach and components integration.  Key components of the system were conceptually designed and modeled for their performance. Component performance has been modeled by using Modelica-based software and validated by high-fidelity models. The system model indicates the advantages of particle-based PTES by removing the temperature restrictions of molten-salt storage and ability to store cold energy by replacing organic liquid media for both performance and safety benefits.

 

Laboratory-scale prototypes were fabricated and to be tested to verify their approaches and operations relevant to the modeling results and product-scale components. The work addresses key component risks including: (1) realizing low gas/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 reversing turbomachinery. We will present thermodynamic models and explore 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. The paper will describe the system layout and discuss development progresses on integrating reversing turbomachinery and fluidized bed heat exchangers, which improve system performance and reduce costs.

Presenting Author: Jeffrey Gifford NREL

Presenting Author Biography: Name: Jeffrey Gifford

Institution: NREL

Email Address: Jeffrey.Gifford@nrel.gov

Authors:

Zhiwen Ma NREL
Josh Mctigue NREL
Jeffrey Gifford NREL
Jason Hirschey NREL
Shin Young Jeong NREL
Munjal Purnkant Shah NREL
Janna Martinek NREL