An NREL project led by Dr. Zhiwen Ma, an NREL researcher and Advanced Energy Systems Mentor, and supported by Colorado School of Mines Ph.D. student Jeffrey Gifford is highlighted for its progress on developing a particle thermal energy storage system for long-duration energy storage applications. The promising technology builds upon concentrated solar power research but extends the thermal energy storage system to standalone applications. The team has spent the past three years working on fundamental testing, developing the lab-scale test stations of novel components, and building and validating models that enable the team to examine how the system would perform at future commercial scales. Now, the team is planning for the next phase of development of this technology for the decarbonization of our energy system.