Environmental profiles of stirling-cooled and cascade-cooled ultra-low temperature freezers

Abstract

The environmental footprint of ultra-low temperature (ULT) freezers as used in bio-repositories, universities and other research organizations is investigated. These freezers, employing the cascade refrigeration system, use between 10 and 20 times the energy of an average household refrigerator/freezer. In addition, they often require high greenhouse gas potential (GWP) refrigerants. A new technology employing the Stirling cycle machine promises to reduce energy consumption of ULT freezers by 50% or more. The cascade and Stirling systems are compared for equivalent sized freezers in terms of embodied energy and equivalent CO2 production from cradle to gate and use, including total equivalent warming impact (TEWI) estimations. End-of-life issues are discussed but not quantified. It is shown that Stirling technology is able to significantly reduce the environmental impact of ULT freezers. © 2012 by the authors.