In 2014, a study on hunger in the U.S. found that more than 46 million people turn every year to agencies and programs of Feeding America, a network of over 200 food banks, including the Vermont Foodbank.

In the highly rural state of Vermont, one in every four residents – an estimated 153,000 residents – have a hunger problem requiring them to turn to  meal service programs, according to the Vermont Foodbank, based in in Barre, Vermont.

Addressing those needs, the Vermont Foodbank acquires and distributes through its three distribution centers over 12 million lbs (5.4 million kg) of food each year to 215 network partners around the state — food shelves, pantries, senior meal programs and other community meal sites.

The Vermont Foodbank has been buffeted by a number of recent challenges, including fulfilling its mission in the face of economic hardships caused by the COVID-19 pandemic.

Another key issue has been the decline in donations of dry nonperishable goods from the grocery industry, which has found secondary markets for those products. To make up the difference, the Vermont Foodbank has been purchasing more perishable foods from diverse sources like farms, individual food retail stores, and small processors. Fresh produce distribution alone increased from less than 250,000lbs (113,398kg) in 2004 to over 2.2 million lbs (997,903kg) in 2019.

With this influx of perishables came a new challenge: providing reliable, environmentally friendly refrigeration for those products. That was difficult to do at the Vermont Foodbank’s warehouse in Barre, an old facility with insufficient refrigerated space (1,400ft2/130.1m2) that used an R404A refrigeration system.

So two years ago, the Vermont Foodbank launched a capital campaign to address refrigeration as well as expansion and renovation of the warehouse.

For the expansion and renovation of the warehouse, Vermont Foodbank recruited KPS Global, a Fort Worth, Texas (U.S.)-based manufacturer of walk-in coolers and freezers. KPS Global worked with ReArch Company, a Vermont-based real estate development, construction, and property management firm, to design an outdoor walk-in cooler and freezer, about 14,000ft2 (1,301m2), attached to the warehouse.

For refrigeration, the Vermont Foodbank selected an Advansor transcritical CO2 (R744) booster system – from Conyers, Georgia (U.S.)-based OEM Hillphoenix – which began operation in October 2019.  The refrigeration delivers 11TR (38.7kW) capacity for the freezer (maintained at 0°F/-17.8°C) and 10TR (35.2kW) for the cooler (maintained at 35°F/1.7°C) The refrigeration contractor for the project was ABC Refrigeration, based in East Syracuse, New York (U.S.).

The transcritical CO2 system uses a Luvata (Modine) air-cooled gas cooler along with three Heatcraft (Bohn) evaporators in the freezer and in the cooler and Emerson CPC RX400 E2 controls.

The system does not employ any energy-enhancing technologies such as an adiabatic gas cooler, ejector or parallel compression – just “subcooled liquid from the Advansor flash tank system,” a standard part of a transcritical booster system, noted Hillphoenix.

Jason Maring, Vermont Foodbank’s Chief Operations Officer, previously worked for a community-owned food cooperative that employed a Hillphoenix transcritical CO2 booster system. The Vermont Foodbank team responsible for the upgrade visited the  co-op to get a better understanding of the system.

The choice of CO2 refrigeration was “driven in large part by its environmentally friendly nature and the corresponding sustainability benefits it offered,” said Hillphoenix in a case study on the project.

Three-year payback

The Vermont Foodbank has estimated that, including a US$55,000 incentive from utility Efficiency Vermont, and expected energy savings, the payback period on the premium paid for the transcritical CO2 system over an HFC system would be approximately three years, along with a reduction of an estimated 170 metric tons of CO2e emissions annually, according to the Hillphoenix case study. Without the incentive, the payback would be about seven years.

“Our goal was to be as environmentally sustainable as possible while still meeting all the functional and budgetary requirements we had,” said Maring. “[Transcritical] CO2 offered us reduced system energy cost, invaluable environmental sustainability and responsibility, along with a refrigerant that was non-volatile, inexpensive and devoid of any harmful effects to our planet.”

“With the performance and efficiency savings we witnessed at the local co-op, along with the financial help we received from Efficiency Vermont and the associated favorable environmental benefits of using CO2, we were sold on CO2 refrigeration as the technology we needed to achieve our mission,” he added.

In a recent update, Maring noted that the transcritical CO2 system “has been working really well so far.”

Working with Efficiency Vermont, the Vermont Foodbank is close to setting up gauges in the warehouse’s electrical system – a process delayed by the pandemic – so that it can measure load and usage data. 

“Overall we’re very happy with our choice so far and are considering retrofitting our other warehouses with CO2 systems,” said Maring.

“[Transcritical] CO2 offered us reduced system energy cost, invaluable environmental sustainability and responsibility, along with a refrigerant that was non-volatile, inexpensive and devoid of any harmful effects to our planet.”

Jason Maring, Vermont Foodbank

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