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

Element 16’s sulfur thermal battery provides a low-cost solution to store and deliver high quality thermal energy.

Element 16 Technologies, Inc


Glendale, CA

Recipient Location


Senate District


Assembly District



Amount Spent



Project Status

Project Update

In January 2023, the project team installed the sulfur thermal storage module at the test site in Duarte, California. The sulfur thermal storage module is the core of the thermal battery and will hold 22 tons of molten sulfur. In mid-2023, all other major pieces of equipment were purchased and tested, including a 100 kW, 240 VAC charge heater, a 10 kW, 400 VAC Organic Rankine Cycle power generation unit, and a 200 kW discharge heat exchanger. The balance of system components are being installed, and Element 16 is on track to commission the system in early 2024.

The Issue

Stationary electrical energy storage systems play many important roles in the electricity grid to enhance grid reliability and flexibility. These systems are expected to grow as the grid continues to evolve with increased penetration of renewables. Pumped hydro-electric storage is by far the largest source of stationary electricity storage capacity on the grid today. However, installation of this technology is limited by geographic location, difficulty to permit new sites and high cost. Electrochemical batteries, especially Li-ion, are recently being researched mostly for deployment on the grid, but their high cost limits their viability in large-scale and long duration applications.

Project Innovation

Element 16's sulfur thermal battery provides a low-cost solution to store and deliver high quality thermal energy due to its low cost, simple chemical composition, high heat transfer rates, and little to no need for any electrical heat tracing due to its low freezing point (~239 Fahrenheit), which guarantees low parasitic load and low O&M cost. The proposed project demonstrates sulfur thermal energy storage technology for electricity storage and generation, thus establishing new paradigms for increasing stored energy capacity and providing new forms of stationary electricity storage systems with the potential to drastically reduce the levelized cost of electricity.

Project Goals

Provide ratepayer benefits of better electricity reliability, lower costs, and safety with sulfur thermal energy storage.
Reduce greenhouse gas emissions and improve California air quality by utilizing sulfur thermal energy storage.

Project Benefits

This project is the first demonstration of sulfur thermal battery technology above 1 MWh capacity. Sulfur thermal batteries can enhance grid resiliency, support transmission and distribution infrastructure, and provide low-cost, long-duration electric storage capacity to the California electric grid. Due to a significantly lower cost per kWh capacity of energy storage compared with electrochemical grid batteries and other thermal batteries in development, sulfur thermal batteries can provide massive energy loads to the electric grid during periods when generation exceeds consumption. Electrically charging the low-cost sulfur thermal battery improves system flexibility by coupling with different types of energy sources and will drive the expansion of intermittent renewable sources such as wind and solar in California. The installation of low-cost sulfur thermal battery systems provides a financial benefit in the carbon market scenarios due to reduced levelized cost of electric storage and increased availability of electricity when required, which reduces the price of electricity during peak price periods and reduces the incentive to turn on fossil fuel peaker plants. Sulfur thermal batteries can also provide long-lasting backup power at industrial customer locations in the event of power outages and improve revenue from onsite generation by providing energy on-demand.

Lower Costs


The low-cost sulfur thermal battery technology can reduce peak demand charges and on-peak electricity consumption, and provide energy arbitrage. The modular nature of the sulfur thermal battery allows charge power and discharge power.

Greater Reliability


The integration of low-cost distributed energy storage can help prevent blackouts, and provide long-lasting backup power during outages. Low-cost distributed energy reduces grid transmission congestion and secures stable electric power.

Increase Safety


By increasing renewable energy generation, fewer natural gas reservoirs will be required and harmful fossil fuel generation can be reduced.

Key Project Members

Hamarz Aryafar

Hamarz Aryafar

Element 16



Brad Alan LLC.


Exponent Engineering, P.C.


Intertek AIM, Industry Services


Match Partners


Element 16 Technologies, Inc


Brad Alan LLC.


Contact the Team