Production Scale-Up of Thermionic Energy Harvesters

This project will scale-up production of thermionic energy harvesters to increase concentrated solar power plant efficiency and reduce capital cost.

Spark Thermionics, Inc.


Berkeley, CA

Recipient Location


Senate District


Assembly District



Amount Spent



Project Status

Project Update

In 2021, this project has made improvements to several pieces of equipment such as the glovebox. For portions of fabrication, manufacturing, and assembly performed in-house, this equipment has accelerated the development of processes and testing for energy harvester components. Following the completion of cost modeling at the LRIP stage, evaluation of multiple manufacturing routes for components and identifying promising manufacturing vendors and partners. This year, we demonstrated larger batch sizes of both encapsulation components and core device components and have a steady manufacturing chain developed for these.

The Issue

California is relying heavily on solar PV and wind for clean renewable generation. However, these generation technologies cannot meet peak demands and therefore need to be supplemented with energy storage. Such storage can be provided by the combination of concentrated solar power (CSP) and thermal energy storage (TES), which resolves issues such as lifetime and reliability that plague battery storage. However, currently CSP adoption is limited by its cost, which is more expensive than PV despite being comparable in price several years ago.

Project Innovation

This agreement is to fund the production scale-up of Spark Thermionics' thermionic energy converter, to low rate production stage. When combined with next-generation CSP, the Recipient's technology can increase the power output by 75-90% relative to today's best CSP plants. This additional power can drive down the cost to 5.6 cents/kWh. Under this agreement, the project team will analyze cost reduction for process development and manufacturing for the core and encapsulation components within the energy harvesters. The project will also validate that the thermionic topping cycle within the energy harvester has adequate heat rejection from CSP that would be necessary for thermal energy storage (TES) to increase the efficiency and power output of a power generating system. With this technology, flexible generation can address the grid-level challenges of solar PV- generated electricity, namely variability, uncertainty, and nonsynchronous generation.

Project Benefits

The high-temperature energy harvesting technology will improve the efficiency of concentrated solar power generation, reducing the capital and operating costs associated with power generating systems. The combination of having a technology that can absorb adaptable amounts of heat and then utilize the heat for time-varying electrical consumption will expedite further large-scale integration of renewable resources to enable California's highly ambitious energy goals. This technology will allow for more integration of renewables for California at a lower cost.

Lower Costs


According to calculations for thermionic topping cycles led by NREL, the levelized cost of electricity (LCOE) for next-generation CSP with TES when combined with a thermionic topping cycle can be as low as $0.056 / kWh.

Greater Reliability


California is targeting 60% of retail electricity to come from renewables by 2030. However, a high penetration of intermittent renewables to achieve this target could jeopardize grid reliability.

Key Project Members

Project Member

Jared Schwede

Project Manager



Lorimer Holding Company LLC


Match Partners


Spark Thermionics, Inc.


Contact the Team