We found no ranking of commercial services, because no data has been published. Among 17 open generators tested in 2025 on the same machine, the heaviest uses 46 times as much energy as the lightest: 4.08 Wh against 0.086 Wh per image. The lightest is a model designed to produce an image in a few computation passes.
Read the source article: AI image generation carbon footprint: 1.3 gCO2e on average