Large-Scale Sulfur Thermal Battery Demonstration for Enhanced Grid Flexibility and Increased Renewable Penetration

Element 16 Technologies, Inc., (Element 16) successfully developed and demonstrated a novel long-duration energy storage technology that uses sulfur in a single-tank configuration to economically and efficiently store and dispatch renewable energy electricity. The core innovation is the use of sulfur, an abundant waste byproduct from the oil and gas industries, to dramatically reduce the cost of Element 16’s thermal energy storage. The team built and tested a pilot-scale, 1.5-Megawatt-hour sulfur thermal battery unit integrated with an electric heater designed to charge with variable excess electricity from renewable generation. The stored heat was converted to electricity using a small-scale, low-temperature power generation unit that can also be used directly for industrial process heat decarbonization. 

A techno-economic model was developed to evaluate the levelized cost of storage of sulfur thermal batteries in grid-connected applications. The levelized cost of storage is the lifetime cost per unit of discharged electricity. 

The sulfur thermal battery charges during periods when electricity demand and prices are low and there is surplus renewable generation, and discharges during peak demand periods when prices are higher. For example, connecting a sulfur thermal battery to a California Independent System Operator node where the electricity price is negative for more than 20 percent of the year, the levelized cost of storage of the sulfur thermal battery was estimated to be 0.08-0.12 $/kilowatt hour electric, which is favorable when compared with 0.15-0.18 $/kilowatt hour electric for Lithium-ion batteries. Adding a sulfur thermal battery to the grid also provides operational flexibility, allowing electric utilities to more effectively balance the electric grid, increase renewable energy penetration, and avoid the need for costly electric grid upgrades. 

This report discusses the successful pilot demonstration of Element 16’s sulfur thermal battery system and the technology-to-market activities of the sulfur thermal energy storage technology, which has secured over $6 million in research, development, and commercialization funding since award of this project.