I t sounds like a lot of trouble and wasted time to me. We use a pressure cooker for beans, roasts, and such. Uses less energy because it cooks in less time.
2nd that. Might be useful if we're reduced to cooking one thing at a time over a campfire or something but as an energy saver? Gotta be kidding. Slow cookers and multifunction cookers do that and you don't have to build the damned things.