Fourth Power Secures $20 Million to Advance Utility-Scale Energy Storage Commercialization
As global electricity demand accelerates due to widespread electrification and the rapid growth of artificial intelligence applications, the need for reliable, affordable, and scalable energy storage solutions has never been greater. Recognizing this critical challenge, Fourth Power, a developer of flexible-duration energy storage technology, has announced the successful close of its $20 million Series A Plus funding round.
The financing round was led by Munich Re Ventures, with continued participation from existing investors DCVC and Breakthrough Energy Ventures. This new investment will propel the company toward the commercial rollout of its modular, utility-scale thermal energy storage system. With the additional capital, Fourth Power aims to complete the commissioning of a fully integrated 1 MWh-e demonstration facility using full-scale commercial components—an important milestone marking the final step before large-scale customer deployments.
Beyond technology validation, the funds will also be used to expand supplier relationships, strengthen customer partnerships, and continue building a strong pipeline of utility and industrial clients eager to deploy next-generation storage solutions.
Addressing a Growing Grid Challenge
“Utilities are in a race to keep up with demand. The grid is under strain from electrification and the computing power needed to drive advancements in AI,” said Arvin Ganesan, CEO of Fourth Power. “Unfortunately, today’s storage technologies are either too expensive, too slow to deploy, or fail to meet both challenges at once. Fourth Power offers an alternative path—scalable and flexible-duration energy storage built from abundant, domestic materials. That combination delivers reliability at a price point that works, both for energy providers and the communities they serve.”
Ganesan’s comments underscore a problem that utilities worldwide are grappling with. As intermittent renewable generation like wind and solar grows, the grid requires cost-effective ways to balance supply and demand. Lithium-ion batteries have played a central role to date, but their costs and limitations in scaling duration make them less suitable for multi-hour or multi-day storage. This gap has created space for new solutions like those pioneered by Fourth Power.
A Track Record of Rapid Progress
Since raising its $19 million Series A round in 2023, Fourth Power has moved quickly to demonstrate its commercial readiness. The company has more than doubled its workforce, reflecting increased demand for engineering and operations expertise. In parallel, it has achieved several significant technological milestones designed to prove the reliability, durability, and safety of its core systems.
Key achievements include building three large-scale accelerated life test rigs that simulate system performance at extreme operating conditions—up to 2400°C. These rigs allow Fourth Power to validate the expected lifetime of its technology, ensuring utilities can count on stable performance over years of operation. The company also developed a self-lubricating graphite pump capable of moving molten tin, designed graphite fittings rated for high-pressure liquid metal containment, and created a scalable inert gas enclosure system to provide an added layer of safety.
Such progress has not gone unnoticed by investors. “Fourth Power is solving a grid problem that is both urgent and unavoidable,” said Peter Ortez, Principal at Munich Re Ventures. “Their system is safer, cheaper, and more scalable than anything we’ve seen in this category. At Munich Re, we seek companies that tackle society’s most pressing risks, and Fourth Power’s technology is a prime example of resilient infrastructure for the energy transition.”
The Breakthrough Technology
At the heart of Fourth Power’s approach lies its innovative thermal energy storage architecture. The system converts electricity into heat, using liquid metal heated to 2400°C as the heat transfer medium. That energy is then stored in durable carbon blocks and later converted back into electricity using proprietary thermophotovoltaic (TPV) cells.
This architecture unlocks several unique advantages. First, the use of ultra-high-temperature liquid metal enables unprecedented power density, which drives down the overall system cost. Second, the modular design separates “power” (the ability to deliver electricity at a given rate) from “energy” (the duration of that output). This means utilities can initially deploy systems with shorter durations to meet immediate needs and then cost-effectively expand storage capacity later as demand grows—without duplicating the entire system.
Most importantly, Fourth Power has achieved a target cost of less than $25 per kilowatt-hour of energy storage (kWh-e), a breakthrough figure that positions its technology as a game-changer compared to traditional lithium-ion batteries.
Investor Confidence in a Scalable Future
For investors, the company’s flexible, modular approach represents a highly attractive alternative to legacy storage options.
“Fourth Power’s technology doesn’t just make incremental improvements—it fundamentally reimagines how we build grid-scale storage,” said Carmichael Roberts, a leader at Breakthrough Energy Ventures. “With electricity demand rising rapidly, we need scalable solutions that can be deployed quickly and affordably. Fourth Power’s flexible-duration approach provides exactly the type of infrastructure-grade storage required for the clean energy transition.”
Rachel Slaybaugh, Partner at DCVC, echoed this sentiment, noting the company’s unique ability to adapt as grid conditions evolve. “Utilities face a basic but critical problem: how to build storage infrastructure that doesn’t become obsolete as demand shifts. Fourth Power’s modular design answers that challenge head-on, and we are excited to see their system move from laboratory validation into real-world customer environments.”
