India’s NTPC ‘wanted something that behaves like pumped hydro’ in selecting Energy Dome CO2 Battery

Our meeting with the chief operating officer (COO) of carbon dioxide-based energy storage company Energy Dome’s storage-as-a-service division marks the third time the site has interviewed Potter at the annual London conference.

As such, it’s a good way to get a feel for how this startup, which is headquartered in Italy, has progressed in a relatively short time.

Energy Dome’s CEO and founder, Claudio Spadacini, invented the proprietary CO2 Battery by combining technology principles and manufacturing techniques from previous roles in biogas and turbine-driven geothermal generation companies.    

Aiming at the emerging market for long-duration energy storage (LDES) applications requiring around 8-hour to 24-hour discharge at full-rated power, the company claims its technology is safe, reliable, clean, cheap to assemble using locally sourced components, and, perhaps most importantly, fully dispatchable.  

We first interviewed Potter in early 2023; Energy Dome’s first megawatt-scale commercial demonstrator had begun operation the previous year on the Italian island of Sardinia. At 2.5MW/4MWh, it proved the concept of using a thermodynamic cycle to store and dispatch energy.  

By our second meeting in 2024, Energy Dome had closed financing on its ‘first-of-a-kind’ large-scale project, also in Sardinia, this time with a 20MW/200MWh configuration.

Since then, utility Engie has signed up as that project’s offtaker with a tolling agreement and Energy Dome has contracted with US utility Alliant Energy to supply the technology for an identical plant in Wisconsin.

Most recently, India’s largest power producer, NTPC, has awarded a 180MWh CO2 Battery project a contract through a competitive tender.

“We’ve gone through that journey, taking a novel technology process using known components, proving the technology, putting it into the market, proving product-market fit,” Potter says.

“Now we’re in that commercial scaling and adoption phase where customers are recognising its benefits across both the build-own-operate side, as well as the equipment supply side, in various different markets.”

While claiming the deals with those blue-chip customers are commercial validation for Energy Dome’s tech—and crucially its business models—Potter adds that negotiations are underway with “several others”, including utilities, data centre hyperscalers, and independent power producers (IPPs).

Characteristics of pumped hydro, decoupling from lithium-ion supply chains

NTPC, formerly the National Thermal Power Corporation, was responsible for generating about one in every four kilowatts of electricity sold on India’s grids in 2023, from its 70GW fleet.

As reported by Energy-Storage.news in late January, the government-owned corporation will deploy a 20MW/160MWh Energy Dome CO2 Battery energy storage system at a power plant in the state of Karnataka.

Energy Dome’s technology partner, Triveni Turbines, had bid into NTPC’s tender to find a carbon dioxide-based LDES technology for pilot deployment, albeit at a large scale.

At that time, NTPC chairman and managing director Gurdeep Singh highlighted some perceived advantages of the tech, even versus the two main established incumbents, lithium-ion (Li-ion) and pumped hydro energy storage (PHES).

Potter says Gurdeep Singh’s quote showed the depth of rigour that NETRA, the R&D arm of NTPC, applies to evaluating new technologies.

“As a public-owned enterprise, [NTPC’s vision is] quite linked to the strategy and the wider vision of India, which is that they don’t necessarily see lithium-ion as the panacea,” Potter tells ESN Premium.

A big part of that is about reducing dependency on Li-ion supply chains and, in particular, the need to import both materials and finished products from abroad, mainly China.

“Lithium-ion materials obviously have certain materials and components and inputs which aren’t abundant in India, which presents risks if they are to develop their own lithium-ion industry, but also the [manufacturing] capacity and overcapacity in China, and competing against that is a consideration.”

Singh noted that supply chains for CO2 Battery manufacture could be established domestically. From a tech point of view, the chairman also highlighted the CO2 Battery’s expected ability to perform many thousands of cycles without degradation, and suitability for delivering many hours of dispatchable power.

To date, pumped hydro has been India’s main choice for LDES applications, and with the national Central Electricity Authority (CEA) forecasting a need for 175.18GWh of PHES by 2031-2032, that role will likely continue.

However, pumped hydro, being very topography dependent, won’t be the answer for all of India’s LDES needs by a long shot, Ben Potter says.

“Pumped hydro costs are extremely competitive, but those are very, very site-specific and difficult to get into the market.”

NETRA was seeking “something that behaves as if it’s a pumped hydro, and there aren’t that many solutions in the market,” Potter says, and Energy Dome’s tech was ultimately selected after what the COO says was a long diligence phase with the R&D agency.

Despite its name and legacy role, NTPC has deployed a lot of solar PV, again in line with India’s national energy vision.

The corporation sees a path to turning that and other renewables into dispatchable ‘Round-the-Clock’ (‘RTC’) baseload energy, Potter claims, while NTPC is also trialling other technologies including vanadium redox flow battery (VRFB) storage.

The challenge of building new infrastructure

Energy Dome is betting that the same characteristics that helped the CO2 Battery stand out in NTPC’s tender will also give it competitive advantages in other markets.

“The way that we designed our product is that we can deliver a product using a supply chain close to that project. For the US, we can support US-based manufacturing, similarly in Europe and elsewhere,” Potter says.

With a simplified bill of materials and experience under its belt from the commercial demonstrator and its projects now in construction, the startup also believes it can scale quickly, with attendant cost reductions.

Asked what challenges Energy Dome still needs to overcome, Potter says the main risks are “project-level issues.”

“We’re in a moment where Western societies have made it difficult to build. That, I think, is something that isn’t unique to energy storage. It’s across all infrastructure,” he says.

“If you ask me about challenges, I’m not thinking about the commercial side or the capital raising. Obviously, all of those are challenging, but if you’ve got the right product and the right team, you can do it. It’s the areas out of your control: as a society, our posture towards building things needs to improve.”