Dynamic, Grid-Flexible Cold Storage Refrigeration Featuring Advanced CO2 Heat Pump, Thermal Storage, and Defrost Controls
Prospect Silicon Valley is demonstarting a heat pump with the capability to use CO2 as a refrigeration and energy storage medium.
Prospect Silicon Valley
Recipient
San Jose, CA
Recipient Location
$70,670
Amount Spent
Active
Project Status
Project Update
The Project Team is in the process of design work as Prospect Silicon Valley moves closer to installing Flow’s 60-ton CO2 heat pump at Straus Family Creamery in Petaluma, CA. In November 2025, Prospect SV, along with key partners in the industry, hosted a webinar focusing on the challenges and opportunities for scaling CO2 systems. Check out the webinar here: https://www.youtube.com/watch?v=MXruojMrpoE
For project updates and upcoming events, visit ProspectSV’s Pathways. https://www.prospectsv.org/pathways
Pathways is a comprehensive engagement program that funnels Prospect Silicon Valley’s projects into three separate tracks: Buildings, Fleets, and Resiliency. Check out the Building Decarbonization Track for more information on this project.
The Issue
In the state of California, cold storage facilities consume an estimated five times more energy per square foot compared to conventional warehouses (California Commercial End-Use Survey, 2006). The annual electric energy use intensity (EUI) is 20.02 kWh/ft2, and the annual natural gas EUI is 5.6 kBtu/ft2, respectively. Improvement of energy efficiency in cold storage facilities is an essential pathway to achieve the carbon emission goal of 40% reduction from the building sector by 2030. Peak demand from large cold storage facilities can have a significant impact on the grid, and system capabilities and operations can result in waste heat, frost buildup, and other inefficiencies. Additionally, the synthetic refrigerants used in these systems have a high GWP, contributing to overall GHG emissions.
Project Innovation
This project will reduce GHG emissions, improve energy efficiency and demand flexibility, save costs, and apply advanced defrost controls. This integrated solution will be demonstrated at multiple cold storage sites at the Straus Family Creamery in Petaluma, CA using a single heat pump system. The Heat Pump system provides low temperature and medium temperature refrigeration through a new hybrid booster system that will interface with custom evaporators that use heat reclaimed from the refrigeration cycle to defrost for little to no energy. Straus Family Creamery will install a 60-ton Answr system with thermal energy storage and advanced controls that will serve multiple cold storage rooms.
Project Goals
Project Benefits
The project will demonstrate an advanced CO₂ heatpump system that significantly reduces greenhousegas emissions, improves energy efficiency, and lowers operating costs for commercial coldstorage facilities. By integrating thermal storage and advanced defrost controls, the system can shift load and participate in demandresponse events, helping reduce peak electricity demand and supporting grid reliability. Customers benefit from lower utility bills, reduced electricdefrost energy use, and improved system reliability through builtin redundancy. The use of CO₂ as a refrigerant eliminates reliance on highGWP refrigerants, reducing leakagerelated emissions. The project supports economic development by enabling new market opportunities for cleanrefrigeration technologies and associated workforce training. Overall, the project provides a scalable pathway for cleaner, more flexible, and more resilient refrigeration systems across California’s coldstorage sector.
Environmental Sustainability
Based on CO2 emission factors in 2021 (electricity - 1,540 lb/MWh), the use of this heat pump integrated with hot glycol defrost and thermal storage systems can reduce a total of 44.3 metric tons CO2 over a year of operation. Considering refrigerant leakage, legacy R448a refrigerants with a GWP of 1387 and average leakage rate of 10% produce another 31.5 MT/yr of emissions. In comparison, this system only emits an additional 0.02 MT/yr from leakage.
Affordability
This project will tackle the economic barrier of high initial costs of heat pumps for commercial cold storage. The customer will save on electricity bills through the high efficiency system and reduced electric defrost. There are also potential savings from demand response program participation.
Safety
This project’s system will showcase the benefit of a safety class A1 refrigerant vs A2L, A3, and B2L, and highlight the reduction of PFAS, TFA, and other harmful toxic chemicals in the water supply.
Reliability
The proposed solution offers a high degree of reliability and robustness in its operation. The heat pump itself is internally redundant and can be isolated for at least 50% capacity operation even with a single point of critical failure.
Environmental Sustainability
Based on CO2 emission factors in 2021 (electricity - 1,540 lb/MWh), the use of this heat pump integrated with hot glycol defrost and thermal storage systems can reduce a total of 44.3 metric tons CO2 over a year of operation. Considering refrigerant leakage, legacy R448a refrigerants with a GWP of 1387 and average leakage rate of 10% produce another 31.5 MT/yr of emissions. In comparison, this system only emits an additional 0.02 MT/yr from leakage.
Key Project Members
Doug Davenport
Subrecipients
Lawrence Berkeley National Laboratory
DMG North
Straus Family Creamery
AlterEngineers
Avida Energy
Match Partners
Sonoma Clean Power Authority
Flow Environmental Systems
DMG North
Straus Family Creamery
