Episode Summary
Executive Summary: Arvin Gannison explains why ForthPower is betting on ultra-low-cost thermal storage as grid-scale infrastructure for a renewables-heavy future. The company heats liquid tin to extreme temperatures, stores that heat in graphite blocks, and converts it back to electricity with thermophotovoltaics. Gannison frames storage as the key enabler of decarbonization, emphasizing supply-chain abundance, utility economics, and flexible long-duration discharge.
Main Topics: Arvin Gannison’s career path and why he joined ForthPower: Gannison traces a nonlinear path from bond trading to policy, EPA regulation, Apple energy policy, and then startup leadership. He says each move was a risk that broadened his understanding of electricity markets and climate policy, and that he joined ForthPower because the technology and founder fit his criteria for a meaningful leap. Why energy storage is central to grid decarbonization: The conversation centers on the idea that future grids will require massive amounts of storage as renewable penetration rises. Gannison argues that current storage deployment is far below what is needed and that the winning solution must be cheap, scalable, and able to handle both short- and long-duration use cases. How ForthPower’s thermal battery works: Gannison describes a system that uses electricity to heat liquid tin to extremely high temperatures, moves that heat into graphite blocks, and later converts the heat back into electricity using thermophotovoltaic cells. The design is positioned as a utility-scale battery with adjustable duration from 10 to 100 hours. Cost, efficiency, and trade-offs versus lithium-ion: The company’s core pitch is that its system costs about one-tenth as much as lithium-ion, even though round-trip efficiency is lower. Gannison argues efficiency matters less in a future grid with volatile prices and more variable generation, where rapid, cheap storage and discharge are more valuable. Supply chain abundance and domestic manufacturability: ForthPower emphasizes using graphite and carbon-based materials that are widely available and potentially manufacturable from multiple feedstocks. Gannison says this avoids dependence on scarce materials and supports domestic scaling, which is important for infrastructure deployment. Utility, hyperscaler, and market-fit strategy: The discussion covers how the technology fits utility business models and may also serve hyperscalers and independent power producers. Gannison stresses that the system is utility-grade, capital intensive, and aligned with how regulated utilities earn returns and manage grid stress. Stage of development and commercialization path: ForthPower’s technology has been de-risked in academic labs for years, and the company is now building a one-megawatt-hour demo near Boston using full-size components. The raised Series A funds are supporting scale-up, pilot deployment, and further validation for utility customers and investors.
Key Arguments: Future grids will require much more storage than has been deployed so far, and current technologies do not scale cheaply enough to meet that need. Thermal storage can be a step-change cheaper than lithium-ion for grid applications, even if it is less efficient round-trip. A storage system optimized for variable renewable generation should prioritize low cost, fast charging, and long duration over maximum efficiency. Graphite and carbon-based materials offer a more scalable supply chain than many critical battery metals. Utilities are natural customers because the system fits capital-heavy regulated business models and helps solve growing load and reliability stress. The technology can support both standalone utility storage and, potentially, hyperscaler or IPP use cases where flexibility and hedging value matter. The company’s commercialization strategy depends on proving a full-size system at demo scale before larger commercial deployments.
Data Points: Series A funding: $20 million - ForthPower’s Series A, led by DC VC with participation from Breakthrough Energy Ventures Storage deployment today vs. needed: 0.1% - Gannison says deployed storage is only about 0.1% of the total amount needed for a renewable grid Battery duration range: 10 to 100 hours - Planned storage duration range for ForthPower’s system, depending on customer needs System size: 100 megawatts - Full-size battery described by Gannison as utility-scale Example storage capacity: one gigawatt hour - Gannison says the full system would be about a 1 GWh battery if configured at 100 MW for 10 hours Liquid tin temperature: 2,400 degrees Celsius - Temperature to which the resistive heater heats liquid tin in the system Graphite blocks in full-size system: 8,000 one-ton blocks - Approximate storage medium count for a 100 MW battery Thermophotovoltaic efficiency milestone: 41% - Mentioned as a Guinness World Record and Nature paper result for TPV cells Recent TPV record: 43% - University of Michigan set a new TPV record, according to Gannison Potential TPV target: 50% - Gannison says there are ways to get to 50% round-trip conversion efficiency in the TPV subsystem Lithium-ion round-trip efficiency: 85% to 90% - Used as the benchmark comparison for existing battery storage efficiency Cost comparison to lithium-ion: 1/10th the cost - Gannison claims ForthPower’s system costs about one-tenth as much to deploy Charge/discharge asymmetry: 2x faster charging than discharging - The system can absorb energy twice as fast as it discharges it Demo location: 30 miles north of Boston - Site of the first demonstration facility Demo size: 1 megawatt-hour - Initial demonstration system under construction
Pivotal Quotes: "the backbone of that will be storage in nine out of 10 scenarios" — Arvin Gannison: Why he left Apple to join ForthPower and why storage is central to the future grid "the cost of storage is very high. And so I knew that there needed to be technologies that represented like an economic step change down in terms of cost" — Arvin Gannison: Explaining the investment thesis behind ForthPower "our competitors become every form of electricity generation" — Arvin Gannison: Describing how low-cost storage changes the company’s competitive set from batteries to the broader power market
Implications: If ForthPower scales, utilities could add cheap long-duration storage to absorb renewables, smooth volatility, and defer grid upgrades. The broader industry takeaway is that cost and supply chain resilience may matter more than maximum efficiency in the next phase of storage deployment.