California Resources Corporation and its carbon management business, Carbon TerraVault, have recently announced the signing of a memorandum of understanding (MOU) with Net Power Inc. to develop gas fired power plants in California that will employ the Allam–Fetvedt cycle. This uses oxy-combustion of carbon fuels and a high-pressure supercritical CO2 working fluid in a highly recuperated cycle that “captures all emissions by design”, with the only byproducts being liquid water and a stream of high-purity, pipeline-ready carbon dioxide.
Under the terms of the MOU, the parties plan to conduct feasibility studies on locating Net Power’s facilities close to CTV’s underground storage vaults. The parties say they plan to focus on the initial deployment of up to 1 GW of generating capacity in northern California employing Net Power’s new modular power plants, with CO2 sequestered in CTV’s reservoirs.
Each of Net Power’s 250 MW utility-scale modular plants is expected to require less than 20 acres.
The MOU marks Net Power’s initial entry into California’s power market and positions CTV as an early strategic partner in the deployment of Net Power’s power technology, the partners note.
The FEED study being conducted with EPC partner Zachry for Project Permian – intended to be the first utility scale plant to employ the ‘Net Power Cycle’ – is close to completion, with initial power generation projected to occur between the second half of 2027 and first half of 2028. Orders for some of the long-lead items have been placed (eg, 345 kV circuit breakers and transformers) and Air Liquide was selected as air separation unit supplier (2 x 50%) for the Project Permian FEED.
Work continues at the La Porte demonstration site to prepare it for four phases of equipment validation in partnership with Baker Hughes. The La Porte site work has included enhancements to piping and instrumentation, relocation of carbon dioxide compression equipment and updates to the distributed control system.
The equipment validation test campaigns at La Porte are “intended to de-risk the utility-scale turboexpander,” which will be deployed as part of Project Permian and future projects. The four test phases are: oxy-fuel burner configuration selection (underway); single demonstrator combustor can validation; single utility-scale combustor can validation; and full demonstrator turboexpander validation.
The Allam-Fetvedt Cycle technology is owned by 8 Rivers and the natural gas powered version is exclusively licensed to NET Power. Investors in NET Power include Occidental (42%), Baker Hughes (4%), Constellation (17%), SK Group (15%) and Rice family (5%).
STEP Demo
The 10 MWe Supercritical Transformational Electric Power (STEP) Demo pilot plant in San Antonio, Texas, has reported successful completion of phase 1 testing, “demonstrating operability, efficiency, and commercial readiness of the supercritical carbon dioxide power cycle.”
The STEP Demo project, led by GTI Energy in collaboration with Southwest Research Institute, GE Vernova’s Advanced Research, the US Department of Energy’s National Energy Technology Laboratory, and several industry partners, is the world’s largest and most advanced indirectly fired sCO2 power plant designed to demonstrate and validate the sCO2 Brayton power cycle (see feature A step forward for sCO2 power cycles).
During phase 1 testing, the plant achieved full turbine speed, 27 000 rpm, operating at 500°C. It generated 4 MWe of grid synchronised power. The data collected from the pilot plant will “optimise the design, performance, and operability of future sCO2 power systems, laying the foundation for widespread commercial deployment,” say its developers.
“This is the largest scale demonstration of the technology to date and, because the plant utilises turbomachinery and process equipment that are representative of commercial implementation, it also demonstrates a scalable technology pathway to larger applications in the 10-100 MW range,” according to John Crane, Advanced Turbines Technology Manager at the National Energy Technology Laboratory.
Following this milestone, the STEP Demo project will enter its final phase, which will involve reconfiguring the plant to enhance efficiency and increase energy output. It will operate at 715°C and demonstrate a Recompression Closed Brayton Cycle (RCBC) configuration, with a generating capacity of about 10 MWe.
The $169 million STEP Demo facility is a joint industry programme that remains open for new partners to join and to obtain “technical insights into the technology and actual operating data.”
Echogen thermal storage
Supercritical CO2 also features in a grid-scale long-duration energy storage technology being developed Echogen Power Systems, which describes itself as a “leader in sCO2 energy systems.”
Echogen’s concept – pumped thermal energy storage (PTES) – employs sand as the storage medium. The process involves using a supercritical carbon dioxide heat pump cycle to convert electricity into thermal energy, which is stored as hot sand. The heat is then converted back into electricity on demand.
Echogen has recently announced the signing of an agreement with Westinghouse Electric Corporation to extend an existing partnership and to pursue the deployment of Echogen’s PTES technology. “This expanded collaboration marks a significant step in the commercial validation of our technology,” says Echogen, which believes its technology will be a key enabler to help achieve the COP29-announced global energy storage target of 1.5 TW. Echogen says its PTES technology is designed to store and dispatch renewable energy for up to 6-48 hours (ie, over much longer durations than lithium-ion).
“This agreement is more than a business milestone—it is a testament to the reliability and scalability of our PTES technology, its capacity to make a meaningful impact on the global energy landscape and our ability to swiftly deploy at scale,” said Phil Brennan, CEO of Echogen.
According to Dr Tim Held, CTO of Echogen, “PTES leverages Echogen’s extensive technology development history in sCO2 energy systems. PTES offers a unique combination of efficiency, low cost, safety and sustainability for energy storage that will enable large-scale deployment of intermittent renewable generation while maintaining grid reliability and stability.”
Echogen says it retains the flexibility to engage with additional partners in pursuit of global expansion for its PTES solution.
Echogen Power Systems, headquartered in Akron, Ohio and founded in 2007 says it is “a leading innovator in sCO2 systems”, with a focus on high-temperature heat pumps and waste heat recovery, as well as PTES.
MAN Energy Solutions’ Esbjerg project
Another company applying sCO2 systems to heat pumps is MAN Energy Solutions. It has recently reported successful commissioning of the first of two units of DIN Forsyning’s 70 MWt Esbjerg facility in Denmark, the world’s largest CO2 based heat pump installation to date.
The new heat pump plant will supply about 280 000 MWh of climate-neutral heat annually to the district heating networks of Esbjerg and the neighbouring town of Varde.
Located at the Port of Esbjerg, the plant uses renewable energy from nearby wind farms and seawater as a heat source. The facility is one of the low carbon projects replacing the city’s shut down coal-fired power plant, and is a critical part of Esbjerg’s ambitious goal of achieving carbon neutrality by 2030. The heat pump operates in tandem with a new 60 MW wood chip boiler that uses sustainable wood chips and a 40 MW electric boiler plant, which serves as a peak and backup load facility.
At the core of the heat pump plant are two oil-free, hermetically sealed HOFIM® motor-compressor units developed and manufactured by MAN Energy Solutions in Zurich, Switzerland (HOFIM being an acronym for high speed oil-free integrated motor compressor). These units use high-speed motors and active magnetic bearings, eliminating the need for oil and reducing maintenance requirements.
