the implication of einsteins mass-energy equivalence formula is mind-blowing to me. one gram of mass, if perfectly converted to energy, makes 25 GWh. that means half the powerplants in my country could be replaced with this theoretical "mass converter" going through a gram of fuel an hour. that's under 10 kilograms of fuel a year.
a fun fact: for the most efficient mass energy conversion, you need a huge spin black hole (preferably naked). Then you can get about 42% conversion. (there was a minute physics video about it i think)
The mass-energy conversion from chemical processes is extremely small compared to nuclear processes, you can't really compare the in any meaningful way