Fourth Power is revolutionizing renewable energy storage with groundbreaking thermal battery technology that could finally make solar and wind power viable 24/7. This Cambridge-based startup’s innovative approach uses superheated molten tin and advanced thermal storage to potentially slash energy storage costs to just one-tenth of current lithium-ion solutions.
How Fourth Power’s Thermal Batteries Work
Fourth Power’s thermal energy storage system operates through a sophisticated three-step process. Initially, electricity from renewable sources heats carbon blocks within argon-filled chambers. Subsequently, the system pumps molten tin heated to an incredible 2,400°C through specialized graphite pipes. Finally, thermophotovoltaic cells convert the intense heat back into electricity efficiently.
Advantages Over Traditional Energy Storage
These thermal batteries offer significant benefits compared to conventional solutions. They provide eight hours of continuous electricity, doubling lithium-ion battery duration. The insulation system maintains remarkable thermal stability, losing only 1% of stored energy daily. Additionally, the technology uses petroleum coke, a waste product from oil refining, enhancing sustainability.
Cost Competitiveness and Market Potential
Fourth Power projects unprecedented cost reductions in energy storage. The company aims to achieve $25 per kilowatt-hour storage costs, dramatically undercutting current technologies. This price point makes renewable energy storage economically viable against natural gas peaking plants. The simplified supply chain and minimal moving parts contribute significantly to these cost advantages.
Development Timeline and Funding
The startup has secured substantial funding to accelerate development. Recently, Fourth Power raised $20 million in a Series A Plus round led by Munich Re Ventures. Major investors include Breakthrough Energy Ventures and DCVC. The company plans to deliver commercial-scale batteries by 2028, following extensive testing and a 1-megawatt-hour demonstration project.
Future Impact on Renewable Energy
Fourth Power’s technology could transform renewable energy adoption globally. Affordable long-duration storage enables reliable 24/7 clean power availability. The technology supports grid stability and reduces dependence on fossil fuels. Ultimately, this innovation accelerates the transition to sustainable energy systems worldwide.
Frequently Asked Questions
How do thermal batteries differ from lithium-ion batteries?
Thermal batteries store energy as heat rather than chemical energy, enabling longer duration storage and higher temperature tolerance. They use molten metals and advanced insulation instead of electrochemical cells.
What temperature does the molten tin reach?
The system operates at extreme temperatures of 2,400°C (4,352°F), requiring specialized graphite pipes that represent the only cost-effective material capable of withstanding such intense heat.
When will Fourth Power’s batteries be commercially available?
The company targets 2028 for commercial deployment, following successful testing of their demonstration project and scaling of manufacturing capabilities.
How does the cost compare to natural gas plants?
Fourth Power projects their thermal batteries will be cost-competitive with natural gas peaking plants while providing zero-emission energy storage and discharge capabilities.
What makes the insulation system so effective?
The insulation uses petroleum coke, a waste product from oil refining, creating remarkably stable thermal conditions that lose only 1% of stored energy per day.
Who are the major investors backing this technology?
Leading investors include Munich Re Ventures, Breakthrough Energy Ventures, and DCVC, demonstrating strong confidence in the technology’s potential and commercial viability.
