Sandia’s concentrating solar quarterly seminar addresses paradigms in thermal energy storage

August 30, 2022 10:05 am Published by

Join Sandia National Laboratories’ National Solar Thermal Test Facility as it hosts, “Thermal Energy Storage Paradigms,” with featured guest Dr. Charles Forsberg, of the Massachusetts Institute of Technology (MIT), Thursday, Sept. 8, 2022, from 9:00 a.m.-10:00 a.m., MT.

This fifth session of the Quarterly Concentrating Solar Seminar Series will include:

  • An introduction to “Solar Thermal Energy Storage,” presented by Henk Laubscher, Sandia National Laboratories
  • “Crushed Rock Ultra-large Heat Storage (CRUSH) with Nitrate Salt or Oil Heat Transfer,” a presentation by Dr. Charles Forsberg, MIT
  • A “Demonstration of a 100 kWh Radially Charged Packed Bed,” presented by Nathan Schroeder, Sandia National Laboratories

Henk Laubscher will begin the session discussing why utility scale energy storage is needed for a successful energy transition to clean energy technologies. The electrification of various commercial sectors like transportation, industrial process heat, manufacturing etc., would contribute to an increase in the current electricity demand. Due to the available-on-demand nature of combustion-based power generation, the energy stored on-site is in the form of energy dense chemical bonds in the fossil fuels. This has a typical high energy density. Replacing the fuel-based energy storage with utility scale thermal energy storage has multiple advantages that are highly valued by the grid operators today, in addition to potentially being cost effective for utility scale applications. Surplus electricity can be converted to thermal energy during low demand periods, stored for later use and then be dispatched by using the same thermo-electric machinery that exists at conventional power generation stations. This conventional generation method continues to deliver grid services that are critical for grid stability and control. The heat from a thermal energy storage facility is simply replacing the heat source from combustion. This aspect of utility scale thermal energy storage is already demonstrated commercially in concentrating solar power plants globally.

Dr. Forsberg will discuss the Crushed Rock Ultra-large Stored Heat (CRUSH) system, which uses crushed rock for sensible heat storage with oil or nitrate salt for transfer of heat into or out of the crushed rock. The capital cost goals are $2-4/kWh of heat at scales many gigawatt hours. The low cost enables long-duration storage from hours to weeks. The crushed rock is 20 to 40 meters high with sloped sides and multiple drain pans under the rock. Rock is heated by sprinkling hot nitrate salt or oil on top of the crushed rock that then trickles by gravity through the rock to the drain pans below. Heat is recovered by sprinkling cold nitrate salt or oil on top of the crushed rock with the fluid heated as it trickles through the crushed rock to drain pans below. The system is located within a large building with insulation on inside walls. CRUSH couples with Concentrated Solar Power (CSP), nuclear or other heat sources to enable dispatchable electricity with base-load operation of the heat source. If applied to CSP, it changes CSP designs to favor larger systems.

Dr. Charles Forsberg is a principal research scientist at MIT. His research areas include Fluoride-salt-cooled High-Temperature Reactors (FHRs) with nitrate salt intermediate loop and utility-scale heat storage including Firebrick Resistance-Heated Energy Storage (conductive firebrick) and CRUSH systems. He teaches the fuel cycle and nuclear chemical engineering classes. Before joining MIT, he was a Corporate Fellow at Oak Ridge National Laboratory. He is a Fellow of the American Nuclear Society (ANS), a Fellow of the American Association for the Advancement of Science, and recipient of the 2005 Robert E. Wilson Award from the American Institute of Chemical Engineers for chemical engineering contributions to nuclear energy, including his work in waste management, hydrogen production and nuclear-renewable energy futures.

Nathan Schroeder will discuss the transition from dispatchable fossil-fuel-based energy generation to intermittent renewable sources and how it will require energy storage to match the energy supply with demand. Packed-bed thermal energy storage utilizes a bed of gravel or rocks that is heated by a stream of heat-transfer fluid (HTF) (air in this case, heated by solar thermal or electricity). When needed, the heat is recovered by flowing the HTF in reverse through the packed bed to generate process heat and/or pressurized steam or supercritical CO2 to generate electricity via a turbine-generator power block. This is an attractive solution because it is composed of inexpensive geomaterials, can store energy for days to weeks, and can be retrofitted into existing thermal generation stations such as coal power plants. The design and testing of a 100 kWh radially charged/discharged packed bed thermal energy storage system will be presented.

Margaret Gordon, Manager of the NSTTF and Concentrating Solar Technologies, will host the seminar.

Tags: , , , , ,