Thermal Energy Storage Startup Fourth Power Raises $19 Million

Fourth Power, a thermal energy storage startup, has secured $19 million in Series A funding led by DCVC, with participation from Breakthrough Energy Ventures and Black Venture Capital Consortium. The funding will support the construction of a 1 MWh electric prototype thermal energy storage facility outside Boston, with an expected completion date in 2026.

Fourth Power’s system converts renewable energy to heat, or thermal energy, which can be stored until needed. The thermal battery works by heating liquid tin and moving it through a piping system to heat stacks of carbon blocks until they glow white hot. The system then exposes thermophotovoltaic (TPV) cells to the light and converts it into electricity.

The company is also expected to use the funding to facilitate its durability tests and expand its engineering team to meet market demands.

“After more than ten years of research and development, we are grateful to reach this crucial milestone in our journey thanks to our funding partners who recognized the innovation and potential of Fourth Power’s thermal battery technology,” said Asegun Henry, founder, and chief technology officer of Fourth Power.

The company claims it can meet the current short-duration (5-hour) needs and the future longer-duration (100-hour) needs. Fourth Power’s thermal battery technology holds several records, including the Guinness World Record for the highest temperature pumping of liquid metal at 1,200°C.

Energy storage is expected to play a major role in sealing up the intermittency issue plaguing the ever increasing renewable energy capacity. In the first nine months of 2023, the sector witnessed a surge in venture capital funding, raising around $8.6 billion in 68 deals, per Mercom’s 9M And Q3 2023 Funding and M&A Report for Storage & Smart Grid.

While lithium-ion technology garnered most of the funding due to its high density and long life cycle, demand for other technologies like thermal energy storage has been on the rise because of its viability over the scarce critical mineral lithium.