The Einstein refrigerator minimizes possible contact with the refrigerant, yet still uses a refrigerant. Perhaps a better idea might be to make a [liquid-cooled refrigerators ?
Traditional liquid-cooling uses one or multiple fan(s) on the radiator to discard heat; an alternative is a Peltier element to cool the radiator. I guess that it won't be as efficient, but the main advantage is that no toxic/environmentally-damaging refrigerants need to be used.
An alternative is to let people continue to use their walk-in refrigerator with open window air conditioner and coolbot, and perhaps have them also integrate outdoor air cooling (winter time). See Proposed GVCS VDP (talk) 15:10, 6 August 2014 (CEST)