As modern utilities grapple with increasing demand resulting from the electrification of various sectors and the rapid advancements in artificial intelligence, Fourth Power has emerged as a notable player in the energy storage landscape. The company specializes in flexible-duration energy storage solutions and has recently secured an impressive $20 million in Series A Plus funding. This funding round, primarily led by Munich Re Ventures, also saw participation from prominent investors like DCVC and Breakthrough Energy Ventures. The financial support will enable Fourth Power to accelerate the rollout of its innovative modular, utility-scale thermal energy storage systems, which are designed to help meet the growing energy needs of communities and businesses.
One of the key objectives of this funding is to support the commissioning of a significant demonstration project. This project will utilize a fully integrated 1 MWh-e system that incorporates full-scale commercial components. Achieving this milestone is crucial as it represents the final step before Fourth Power can begin deploying its technology for customers. With this capital, Fourth Power also aims to strengthen its relationships with suppliers and customers, expanding its customer base in the process.
Since its earlier funding round in 2023, where it raised $19 million, Fourth Power has made impressive strides. The company has doubled its workforce, which reflects its growth and commitment to advancing its technology. It has also achieved several engineering breakthroughs that confirm its readiness for the commercial market. One of the notable developments includes the construction of three large-scale accelerated life test rigs. These rigs are crucial for testing the durability, safety, and long-term performance of Fourth Power’s subsystems at extreme temperatures, reaching up to 2400°C.
The engineering team has made several significant advancements, including the design of a self-lubricating graphite pump capable of efficiently moving molten tin and high-pressure-rated graphite fittings to ensure the safe containment of liquid metal. Additionally, the company has created a scalable inert gas enclosure system that enhances the safety and efficiency of the storage process.
A central innovation in Fourth Power’s technology is its unique architecture. The thermal energy storage system operates by converting electricity into heat through the use of liquid metal, heated to an extreme temperature of 2400°C. This heat is stored in specially designed carbon blocks, and when energy is needed again, it is converted back into electricity utilizing proprietary thermophotovoltaics, or TPVs. The choice of using very high-temperature liquid metal for heat transfer is a game-changer. It allows for an unprecedented power density, which, in turn, significantly reduces the overall costs associated with the energy storage system.
The modular design of Fourth Power’s technology allows for a flexible separation of power and energy capacities. This is a key advantage for utilities. They can expand their energy storage duration over time in response to changing energy demands, without having to invest in duplicating the entire system. At a cost of under $25 per kilowatt-hour of electricity stored, this flexibility offers customers a financially viable way to adapt to the evolving energy landscape, especially compared to traditional lithium-ion batteries that require a complete system overhaul to extend storage duration.
The company is on track to announce its first commercial partnerships by 2027, which will mark an exciting advancement in making energy storage more accessible and effective for utility providers and consumers alike. With its groundbreaking technology and commitment to innovation, Fourth Power is set to play a pivotal role in shaping the future of energy storage and grid reliability.
KEY QUOTES:
“We’re in a race between the growing need for reliable electricity and the grid’s ability to provide it quickly and affordably. Existing solutions are too slow to deploy, too expensive for customers, and oftentimes both. Fourth Power offers a new path forward: scalable, flexible-duration energy storage built from abundant domestic materials. It’s how we deliver reliability at a price point that works—for energy providers, their customers, and the future of the grid.”
Arvin Ganesan, CEO of Fourth Power
“Fourth Power is solving a grid problem that’s very real and very near-term, and they’re doing it with a system that’s safer, cheaper, and dramatically more scalable than anything we’ve seen in this category. We focus on companies tackling the biggest risks facing society. And we believe Fourth Power’s approach represents exactly the kind of resilient infrastructure investment the energy transition demands.”
Peter Ortez, principal at Munich Re Ventures
“Fourth Power’s modular approach solves the fundamental challenge utilities face: how to build storage infrastructure that adapts as grid conditions evolve. What excites us about the next phase is seeing their technology move from laboratory validation to commercial readiness.”
Rachel Slaybaugh, partner at DCVC
“This technology doesn’t just incrementally improve on existing solutions, but completely reimagines how we approach the problem. With energy demand rising rapidly, we need storage technologies that can scale cost-effectively alongside that growth. Fourth Power’s flexible-duration approach is that kind of infrastructure-grade solution.”
Carmichael Roberts of Breakthrough Energy Ventures
