I'm with you on more ethical solutions being available, but efficient? In turns of total energy usage required to go from (often unethically acquired) training data to a manifestation of a prompt as an image, maybe.

But regarding the effort and efficiency when purely generating an image? I think not.

There is a person on Lemmy running GenAI models locally (on their own machines) using solar power, and honestly, that's totally fine by me. I'm also fine with a DM generating some art for their next hombrew game they run with a couple of friends.

Acquisition of training data and the environmental impact of data centers (not only for AI usage) are still problems to be solved, though.