Is there any theoretical way of converting ambient heat to electrical energy?

For example if you had a planet where it's 1000C could something like this in theory extract electricity from the heat itself? Like is it theoretical possible to have a close loop where hydrogen produce more electricity than whats used to produce hydrogen?

Hydrogen can be generated from energy supplied in the form of heat and electricity through high-temperature electrolysis (HTE). Since some of the energy in HTE is supplied in the form of heat, less of the energy must be converted twice from heat to electricity, and then to hydrogen. Therefore, potentially less energy is required to produce hydrogen. Nuclear heat could be used to split hydrogen from water.