Thermal Energy Storage and Integration Methods for Grid-Scale Electric Energy Storage

Z. Ma, P. Davenport, J. Martinek, J. McTigue, C. Turchi
National Renewable Energy Laboratory,
United States

Keywords: thermal energy storage, grid energy storage, thermal power cycle

Summary:

The rapid growth of renewable energy increases the importance of economically firming the electricity supply from variable solar photovoltaic- and wind-power generators. Energy storage will be the key to manage variability and to bridge the generation gap over time scales of hours or days for high renewable grid integration. The integration of renewable power and storage of excess electricity has several significant and positive impacts including: (1) expanding the renewable energy portion of total electricity generation, (2) improving the peak-load response, and (3) coordinating the electricity supply and demand over the grid. Grid-scale energy storage can potentially complement the reduction of fossil-fuel baseload generation and mitigate the risks to grid reliability when a large portion of grid power comes from variable renewable sources. Several energy storage methods are deployed or under development, including mechanical, chemical or electrochemical, and thermal energy storage (TES). Comparing the economic potential of each technology for different scales and applications helps identify suitable technologies to support high renewable grid integration. Despite the progress of TES technologies developed and deployed with concentrating solar power (CSP) systems, TES has been undervalued for its potential role in electric energy storage. This presentation introduces TES methods applicable to grid energy storage and particularly focuses on solid particle-based TES to serve the purpose of grid-scale electric energy storage (EES). The objective is to provide various possibilities of using TES systems for electric storage, and to show the potential of TES systems for EES applications that complement other energy storage methods such as batteries, compressed air energy storage, or pumped storage hydropower.