Some mini refrigerators are energy efficient, and others are not. The best way to determine whether a mini refrigerator is energy efficient is to look for the Energy Star designation from the Environmental Protection Agency.
The difference between energy-efficient refrigerators and non-energy-efficient refrigerators are the devices they use to bring power to the units. A compressor is far more efficient than a thermoelectric cooler because a compressor does not use as much electricity. Any mini refrigerator holding the Energy Star label is fairly efficient under EPA standards. Consumers may enter individual product names on the EPA website to learn if the products are deemed energy efficient.