Update | Supercritical CO2


Systems, Nov/Dec 2023, pp 14-18). 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


Ice/water tank


Silo(s) Elevator


Conveyor Heat exchanger(s)


Echogen PTES schematic Charging cycle: Heat pump (refrigeration) cycle. Uses electrical power to move heat from a cold reservoir to a hot reservoir. Creates stored energy as both “heat” and “cold.” Generating cycle: Heat engine (power) cycle. Uses heat stored in hot reservoir to generate electrical power. “Cold” energy improves performance of heat engine (source: Echogen)


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.”


Schematic of heat pump system employing sCO2 and HOFIM® (source: MAN Energy Solutions)


Liquid CO2


Heat source


Supercritical CO2 HOFIM® compressor Gaseous CO2 Supercritical CO2


Sensible heating


motor-compressor


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


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.


Renewable power


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.


12 | January/February 2025| www.modernpowersystems.com


systems”, with a focus


Ice slurry generators


Power block


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