Only true for our current computers and not true with reversible computing.
With reversible computing you can use electricity to perform a calculation and then "push" that electricity back into a battery or a capacitor instead of dumping it to the environment.
It's still a huge challenge, but there is a recent promising attempt:
"British reversible computing startup Vaire has demonstrated an adiabatic reversible computing system with net energy recovery"
"British reversible computing startup Vaire has demonstrated an adiabatic reversible computing system with net energy recovery"
https://www.eetimes.com/vaire-demos-energy-recovery-with-rev...
https://vaire.co/
Short introduction video to reversible computing:
https://www.youtube.com/watch?v=rVmZTGeIwnc