Efficiency Vermont, an efficiency utility under the auspices of the nonprofit Vermont Energy Investment Corp. (VEIC), is overseeing a test of a CO2 condensing unit in a supermarket, one of the first such installations in the U.S.
Intended to start in the second quarter of 2019, the pilot will measure the energy efficiency of the condensing unit in comparison with that of an HFC unit. The ultimate goal is to award financial incentives for purchasers of a more energy-efficient system, explained Ali White, energy consultant for VEIC.
“Our job is to highlight the business case for installing a CO2 condensing unit,” said Ethan Bellavance, senior energy consultant for VEIC.
In addition to electricity savings, Efficiency Vermont is looking at the potential for “higher-grade waste heat to offset fossil fuel consumption” as a result of the higher compressor discharge temperatures associated with CO2, said Bellavance.
“CO2 condensing units offer tremendous potential for commercial refrigeration applications, from large supermarkets to small-format convenience stores.”– Danielle White, North American Sustainable Refrigeration Council
Efficiency Vermont sees a CO2 condensing unit as the right size for small- and medium-size refrigeration loads at the state’s many small “mom-and-pop” stores as well as convenience stores, micro-breweries and dairies, White said. “We’re focusing on [a system] that is in between a self-contained propane case and a rack system.”
These businesses have “simultaneous cooling and heating loads” that currently use HFC condensing units but could benefit more from a CO2 system, she said, adding, “We see the CO2 condensing unit having a lot of potential for the Vermont market.”
In the test, the CO2 condensing unit will chill glycol, which will serve a “couple of loads,” while an HFC unit will serve other loads, said Bellavance. The study will meter the energy usage of each system and compare their BTU per watt per hour.
CO2 condensing units, while widely employed in Europe and Japan, are rare in the U.S. But Energy Vermont, funded by Vermont utility rate payers, found a North American manufacturer willing to produce one for the test, as well as a Vermont contractor and a retailer willing to conduct the pilot. (Names of the parties were not available.)
“CO2 condensing units offer tremendous potential for commercial refrigeration applications, from large supermarkets to small-format convenience stores,” said Danielle Wright, executive director of the North American Sustainable Refrigeration Council, in a statement. “This technology makes the transition to low-GWP refrigerants more economically feasible by allowing for retrofit options and offering efficiency gains.”
In October, NASRC and VEIC collaborated on a one-day natural refrigerants workshop sponsored by Danfoss and True Manufacturing in Burlington, VT. At the workshop, White discussed the CO2 condensing unit pilot.
Founded in 1999, Energy Vermont is the first energy efficiency utility designed to be separate from an electric utility, which typically handles efficiency incentives in-house, noted White.
Among its research projects, Energy Vermont looks at energy efficiency in refrigeration. “We’re seeing a reason for end users to move to natural refrigerants for environmental and economic benefits,” said Bellavance.
Efficiency Vermont runs a statewide Efficiency Excellence Network of skilled service providers, providing training to design, install and service efficient systems. Before installing a CO2 condensing unit, “we would have a conversation with refrigeration technicians to make sure they are comfortable taking on a new refrigerant with higher pressures,” said Bellavance.