To meet the growing demand for renewable energy on the grid, Boston-based Fourth Power is developing ultra-high temperature “sun in a box” energy storage tech based on thermophotovoltaic (TPV) cells.
The technology is reportedly ten times cheaper than lithium-ion batteries and far more powerful and efficient than any other thermal battery. Its high-density battery system is based on its Guinness World Record achievement for high temperature in its patented liquid metal heat transfer system, which allows for operation at almost half the sun’s temperature.
The company has received $19 million in Series A funding to scale its cost-effective thermal energy storage solution, which can store energy for both short- and long-term durations and convert it back to electricity when needed. The investment round was led by the venture capital firm DCVC, with participation from Breakthrough Energy Ventures – set up by Microsoft billionaire Gates to back promising energy technologies – and the Black Venture Capital Consortium.
In addition to scaling its thermal battery technology, the funding will also support the construction of a 1 MWh-e prototype facility outside Boston, which is expected to be completed by 2026.
Without energy storage, renewable energy sources like wind and solar can only be used when generated, making it difficult to reduce our reliance on fossil fuels while ensuring a stable energy supply. However, Fourth Power’s solution leverages renewable energy to heat carbon blocks to temperatures so hot they glow like the sun and later release that heat on demand to the grid as electricity.
Fourth Power’s system converts renewable energy to heat, or thermal energy, which can be stored until required. The thermal battery works by heating liquid tin and moving it through a closed-loop piping system to heat stacks of carbon blocks until they glow white hot.
When power is needed, the system exposes thermophotovoltaic (TPV) cells to the light emitted by the glowing white-hot plumbing system and converts it into electricity. This is similar to traditional solar generation but uses light from very hot graphite rather than light from the sun to produce electricity. The graphite reaches temperatures as high as 2400°C, which is still lower than the sun’s surface temperature of 5,500°C.
This solution is designed to maximize the value of renewable energy generation and offer grid operators control and flexibility at the lowest cost compared to other energy storage options.
What’s more, the system is modular and scalable, which means that more carbon blocks can be added to increase storage duration, allowing for growth with the grid as renewable generation increases.
“Fourth’s Power’s solution is an engineered sun-in-a-box,” said Zachary Bogue, co-founder and managing partner at DCVC. “We are thrilled to join forces with this exceptional team, whose best-in-class technology can greatly increase the production and use of renewable energy.”
Fourth Power’s approach to utility-scale energy storage considers the expected growth of wind and solar generation. Their solution enables the storage of renewable energy that would otherwise be wasted, and the stored energy can be discharged over any period from a few hours to a few days. This flexibility to discharge within seconds is helpful for grid operators to ensure a reliable grid and 24/7 power. Fourth Power can meet both short-duration (5-10 hour range) and longer-duration (100-hour) needs and discharge within seconds, making it unique and cost-effective.
In addition, Fourth Power’s thermal battery technology holds several records, including the Guinness World Record for the highest temperature pumping of liquid metal at 1200°C degrees. Beyond the development of its initial 1 MWh-e facility, the funding will facilitate rigorous durability tests and expand the company’s engineering team to meet the market’s growing demands.
“Our vision has always been to tackle climate change by making renewable energy – which is the most cost-effective form of power – a reliable resource for the grid to use at all hours of the day,” said Fourth Power’s CEO, Arvin Ganesan. “We need utility-scale energy storage that can grow with the grid to make this a reality on a global scale. With the support of our investors, Fourth Power will accelerate our mission and reshape the clean energy landscape by making grid-scale thermal battery storage the most cost-effective solution for power production. We are energized by the opportunity to create a better, more sustainable future.”
