Basically, converting from one form of energy to another usually can be done at 50%. The lone exception is voltage potential (electricity) where we can get 90% for motion but 10% for anything else. And when you use motion for transport you have all the problems of a heavy battery reducing efficiency. This is why we can make an EV but not an electric plane. Then there are the problems to do with storage (remember 2 conversions so 25% efficiency there unless you use a battery). Finally, remember that capitalism is really good at efficiency. When people started trying to find energy uses to cut, this was easy in less developed places but in the US it was nearly impossible. Every cut caused problems elsewhere (even for something as minor as an HVAC fan). Ironically we learned this during COVID when the older "inefficient" buildings were healthier than the newer ones because they moved less air.