Biological energy conversion enables growth by supplying molecules capable of activating others. Hydrolysis energies - or group transfer potentials - are a key focus area in understanding growth by energy harvesting, but how might this have worked in emerging metabolisms? In this talk I’ll briefly overview group transfer potential as it exists in biology today and then move on to recent results which help us imagine ancient forms of group transfer potential during metabolic evolution. Turning to kinetics and thermodynamics, I’ll discuss environmental constraints on different forms of group transfer potential, ranging from phosphate esters to sulfur containing thioesters. This talk will help us frame an understanding of where life may have began using concepts from chemistry and metabolism.