It's important to note the fact that the heat in the core does not exist in isolation of other fields. The Earth is a dynamo system, and the energy in the core

It's important to note the fact that the heat in the core does not exist in isolation of other fields. The Earth is a dynamo system, and the energy in the core is connected to the planet's magnetic field, the energy bound up in its orbit around the sun, and its gravitational field.