Energy Storage 10× Cheaper Than Lithium-Ion Batteries Is Coming For Your Fossil Fuels
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US presidents come and go, but the renewable energy transition is permanent and inevitable. Also, follow the money. Despite the abrupt shift in federal energy policy this year, investors are still banking on next-generation solutions to the climate crisis. Exhibit A is the US startup Fourth Power, which has just nailed down $20 million to bring its new thermal energy storage system to market.
Energy Storage 10× Cheaper Than Lithium-Ion Batteries, Seriously?
A new, extra-cheap energy storage system will help kickstart the US energy transition back into high gear if and when (spoiler alert: when) the current occupant of the White House leaves office as scheduled on January 20, 2029. For that matter, the only two energy storage systems in widespread use today are the same ones that existed during the renewables-friendly administrations of former Presidents Obama and Biden, but we need more of the kind of long-duration, inexpensive systems that are needed to smooth out the bumps in a grid fully saturated with wind, solar, and other renewable energy resources.
One of those two types currently in widespread use is pumped hydropower. The basic technology has been in use for over a century and it currently accounts for about 95% of long-duration energy storage in the US. There are some opportunities for expansion in the coming years, but scope of the field is limited by the availability of suitable elevation and water resources, among other obstacles. New types of pumped storage are in development, but similar limitations apply.
Lithium-ion battery arrays are the other form of energy storage. Utility-scale battery systems have a much more flexible scope of application, but they don’t deliver on the long-duration side. They can hold onto energy for a handful of hours, which is enough to handle routine daily grid tasks and the occasional emergency. However, the US Department of Energy (such as it is today) has been on the prowl for systems that last at least 10 hours, on up through multiple days, weeks, and even seasons, to complement a longstanding grid modernization program that calls for more renewable energy and more decentralized, distributed energy resources.
Yes, Seriously
Fourth Power sailed across the CleanTechnica radar back in 2023, when it raised $19 million in Series A funding to support the development of a 1 megawatt-e prototype thermal energy storage system. The eye-catching goal was to become 10 times cheaper than conventional lithium-ion batteries, due in large part to supply chain savings.
The lost cost of materials is typical of thermal storage systems, which collect heat in the form of sunlight or an electrical current supplied by renewable resources. Fourth Power has added a twist of its own, using melted tin as a transfer medium that shunts electricity-sourced heat into carbon blocks for storage. To discharge the blocks, Fourth Power applies a proprietary system that transfers heat back into electricity.
“The company’s use of very high-temperature liquid metal for heat transfer achieves unprecedented power density, dramatically reducing overall system costs,” Fourth Power explains.
The ability to cut down on commercial-scale manufacturing costs remains to be seen, but two years ago, Fourth Power was confident that the materials alone would make the difference. “By using readily available and less expensive materials, the overall system cost is lower, enabling energy storage that is ten times cheaper than lithium-ion batteries,” Fourth Wall stated in a press release in December of 2023, referring to its low cost tin-and-carbon formula.
Fourth Power is still confident. The system was still undergoing additional testing back in 2023, but with Series A funding in hand, the company doubled the size of its team, including its engineering staff, enabling it to ramp up the testing phase.
Highlights of that effort included three scaled-up test rigs aimed at validating the durability, safety, and lifetime performance of system components, subjected to temperatures up to 2400°C.
Yes, Seriously, And It’s Also A Long-Duration Energy Storage System
The next step is putting all the pieces together into one fully assembled demonstration unit, and earlier this week Fourth Power announced that it had raised another $20 million in Series A Plus funding, earmarked for launching the new system into commercial application.
“The funding will support commissioning of an integrated 1 MWh-e demonstration using full-scale commercial components and is the company’s final step before customer deployments,” Fourth Power explained in a press statement. “Additionally, this capital will be used to deepen partnerships with suppliers and customers further and grow the customer pipeline.”
In the new announcement, Fourth Power stated that its thermal energy storage system costs less than $25/lWh-e and is scalable up to 100+ hours of storage. The system is also modular, reducing the expense of follow-on additions to a customer’s energy storage needs.
“Fourth Power’s modular system provides flexible duration from 5 to 100+ hours, allowing utilities to start small and scale seamlessly as grid conditions evolve,” the company emphasizes.
Follow The Money To Next-Generation Energy Storage
Fourth Power is playing its forthcoming commercial partnerships close to the vest for the time being, but the company is happy to unveil that the firm Munich Re Ventures spearheaded the Series A Plus round of funding, with DCVC and Breakthrough Energy Ventures returning for another go-around.
Breakthrough Energy Ventures is a familiar face on the pages of CleanTechnica. Among the other two Series A Plus investors, Munich Re Ventures is of interest because it falls under the umbrella of the sprawling risk management firm Munich Re Group. “With $1.2 billion in assets under management, Munich Re Ventures invests in the most innovative startups, transforming the future of risk and risk transfer,” MRV says of itself.
“MRV’s experienced investors are financially-driven while focused on the strategic interests of Munich Re and the broader insurance industry,” the firm emphasizes.
DCVC is also an interesting case. In an interview with CleanTechnica two years ago, DCVC founder Zach Bogue noted that venture capital field was once shy of attacking big cleantech problems, preferring governments and other financial entities to take on the risks. Today’s computing power has opened the door. “But now there’s a growing subset of companies that rely on modern computing approaches — AL, ML — just computational approaches to make things more Capex and Opex efficient and that is pretty exciting,” Bogue explained.
Accordingly, DCVC describes itself as a “deep tech venture capital” firm. “Over more than a dozen years, the firm has backed brilliant entrepreneurs using computational approaches to solve trillion-dollar problems in the real world across a broad set of industries, especially those that haven’t seen material progress in decades,” DCVC adds.
That thing about “material progress” pretty much describes the state of affairs in energy storage technology today, but not tomorrow. Forth Power is sharing the long duration space with other promising storage innovators that are readying themselves for a booming market in the years to come, regardless of the abrupt shift in federal energy policy this year.
Photo (cropped): A new long duration energy storage system that deploys molten tin as a heat transfer medium has received $20 million in Series A Plus funding (via CleanTechnica archive).
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