Polaris: from laboratory prototypes to market-ready sustainable magnetic beverage coolers

• First commercialization of magnetic beverage coolers, with 43 units deployed and operated up to TRL 9. • A unified optimization framework for maximizing plug-in efficiency. • Cost-effective design enables competitive performance, making magnetic refrigeration affordable. • Major practical improvements, including 80 % power reduction over four years. We report here on the development of the first CE certified commercial magnetic beverage cooler, marking a decisive breakthrough from decades of laboratory prototypes to fully market ready magnetic refrigerators operating in supermarkets. Using a unified optimization framework that integrates experimental insights from both component level and system level testing, this work captures the complex interplay from which several critical design knobs emerge. By prioritizing plug-in coefficient of performance (COP) over thermodynamic COP, the optimized configuration achieved a specific cooling capacity of 131 W/kg, a plug-in COP of 1, and a second law efficiency of 5.4 % at a 15 K temperature span. A temperature span of 28.5 K was realized through a cascade multi stage active magnetic regeneration system using Gd under 0.8 T, underscoring the potential of Curie temperature tailoring for future freezer applications. Full plug-in power consumption was addressed, delivering an 80 % reduction in total power draw and lowering noise levels to 57.8 dB through streamlined component design. The successful commercialization including months-long supermarket deployment at a stable 6 °C, advanced the technology readiness level from TRL 6 to TRL 9.