GreenChill webinar shares experiences with two new transcritical CO2 stores in USA

On 14 January 2014, The US Environmental Protection Agency (EPA) hosted a webinar on initial experiences with transcritical CO₂ systems in US supermarkets. In the webinar, leading food retailers Hannaford and Whole Foods outlined some of the key challenges and shared their views on the future trends with CO₂ refrigeration systems.

The GreenChill webinar aimed to present first experiences and lessons learnt of two GreenChill Partner companies that have recently opened stores with transcritical CO₂ refrigeration systems: Hannaford's store in Turner, Maine, and Whole Foods' store in Brooklyn, New York.

Harrison Horning: possible future trends for refrigeration systems in food retail sector

Harrison Horning from Delhaize America presented on Hannaford's new CO₂ transcritical store in Turner, Maine. Delhaize America opened its first 100% CO₂ transcritical store in the US in July 2013. In the store, a CO₂ transcritical booster system for low and medium temperatures was installed and supplemented with a glycol heat reclaim system and a warm gas defrost system. The store was recognised with GreenChill platinum-level certification recently.

Horning shared experiences with the audience on the Turner store. He confirmed the CO₂ transcritical system is running smoothly. He stressed the importance of selecting experienced and reliable system suppliers, installers, and technician training from suppliers in the project. In the store, the rack for the new CO₂ booster system is manufactured by Carnot Refrigeration and equipped with Micro-Thermo control systems by Parker. The construction of the plant has been carried out by Hannaford’s refrigeration in-house team.

From the perspective of retailers, cost is a very important factor in choosing refrigeration systems. For the case of a pilot supermarket, Horning explained that Hannaford is more interested in the energy savings potential of the CO₂ transcritical system and therefore they do not mind investing a little bit more. In his presentation, he highlighted the level of incremental cost for transcrtical systems in the current market and their targeted level in the future. As a retailer, Horning explained they pay close attention to the system’s energy consumption, reliability and maintenance.

Horning regarded that the future trends in the commercial refrigeration sector will include:

Incorporating all energy efficiency features for “any climate” solution (heat reclaim, subcooling, parallel compression, ejectors, intelligent control algorithms)
Considering hot gas defrost for efficiency increase
Design to be more like a conventional system
Lower incremental cost as market evolves
Implement on remodels/retrofits

J'aime Mitchell: achievements and challenges in Whole Foods' new CO2 transcritical store in Brooklyn

In her presentation titled: “ Extending integrated design CO₂ transcritical system”, J'aime Mitchell from Whole Foods Markets gave a presentation about their new CO₂ transcritical store in Brooklyn that opened in December 2013. Mitchell also introduced other CO₂ stores of Whole Foods Markets. The food retailer has installed many CO₂ systems into its stores in the USA and until now it has 11 stores equipped with CO₂ secondary or CO₂ cascade systems.

The CO₂transcritical store in Brooklyn is equipped with a CO₂ transcritical booster refrigeration system that uses only carbon dioxide as a refrigerant. The refrigeration system is expected to contribute energy savings greater than 60% above the ASHRAE90.1-2007 baseline for the whole building.

The store’s water reuse system could provide simultaneous heating and chilled water year-round through cogeneration of heat and electricity. The new store also features a series of other state of the art clean technologies including car charging stations powered by wind and solar energy, self-generated light-emitting diode (LED), parking lot lighting and six solar canopies. The Brooklyn store also features a rooftop greenhouse - a 20.000 sq² (1.859 m³) urban garden to grow vegetables and herbs.

According to Mitchell, some of the practical challenges they faced in the CO₂ transcritical project include:

Higher initial system cost compared to DX system,
Navigating permit requirements,
Unexpected costs due to regulatory modifications,
CO2 configuration & case control prefabrication across all case vendors,
Long term in collecting analytic data to compare performance, and etc.

Mitchell regarded that in order to tackle these challenges, they need to work together with refrigeration industry partners on R&D projects for CO₂refrigeration, and test and share results of other configurations.