Synergies Between Thermal and Battery Energy Storage Systems

Lead Performer: National Renewable Energy Laboratory (NREL) — Golden, CO
FY19 DOE Funding: $750,000
Project Term: October 1, 2018 - March 31, 2020 
Funding Type: Direct Funded

Project Objective

Problem: Behind-the-meter energy storage is needed to mitigate high electric demand charges, and to facilitate building-sited renewables and electric vehicle (EV) charging. Behind-the-meter storage systems can include electrochemical and/or thermal, but determining which and how much of each to use, and how to size and control them together, is largely unknown.

Research questions:

• Thermal + battery storage synergies: What are the synergies between thermal and battery energy storage, and how can using them together minimize building operating costs?
• Multiscale characterization: How do we characterize thermal energy storage (TES) from materials to system scale, and compare between them and to other forms of energy storage?
• Thermal storage needs: What range of energy capacity and charge and discharge power are appropriate for behind-the-meter thermal energy storage, for both situations with and without battery energy storage?

Approach: Answering these questions thoroughly requires an iterative model-design-experimental framework at multiple scales. This framework includes the following areas:

1. Multiscale models to design, probe, and evaluate different thermal storage options and thermal + battery energy storage solutions for a range of building types and climates.
2. Multiscale experiments to characterize thermal storage from the materials to the integration scale, including integration with battery and building energy management system controls.
3. Determining system designs of thermal and battery energy storage that minimize building energy costs, increase energy efficiency, and shift and shape the electric load to minimize the grid impact of buildings. These new designs will consider existing and new thermal storage technologies, and will help guide future thermal-storage R&D.

Project Impact

The above modeling and experimental framework enables modeling, design, sizing, characterization, and evaluation of behind-the-meter storage systems, including thermal storage at multiple scales.

Characterization will include thermal storage material degradation due to cycling and environmental conditions, potential failure mechanisms, and cycling dynamics (charge/discharge rates). Integrated, multisystem modeling will help quantify synergies of electrochemical and thermal storage, and integrated experiment with simulated weather, building loads, and electric grid profiles will characterize interoperability and controls.

This project’s goal is to determine today’s available thermal + battery storage solutions, future possible system-level solutions, and the thermal storage R&D needs to enable these future solutions.

Contacts

DOE Technology Manager: Sven Mumme
Lead Performer:  Jason Woods, National Renewable Energy Laboratory (NREL)