Looking for options with at least some grounding in science:
Several hundred years in our future, a group of wealthy philanthropists lavishly funded a colonisation project designed to create a Utopia. Their theory was that human violence is a cultural phenomenon, which occurs because of traumatic childrearing practices, poor social structures, and generational contagion.
The controlling AI found a suitable planet, did some modest adjustments to make it more habitable, seeded it with genetically-engineered plants which naturally produce a vast range of medicines (including contraceptives), and human volunteers raised the first generation of native-born humans without any knowledge of the colony ships, or the history of the species. Just general knowledge of biology, chemistry, geology, etc, and all the specific knowledge of how to live on this particular world.
When the first generation were old enough (the second generation was successfully raised, and the third generation was being born), the human volunteers gradually withdrew, one by one, until there was nobody left on the planet with any knowledge of the colonisation.
Part of the theory was that humans evolved to live in villages of less than 200 people, so the society was organised into villages, approximately a day's walk apart, which practiced permaculture.
The centre of each village is the Hearth - a building which provides shelter, cooking facilities, and apparently endless energy. The hearth has an oven, so that food can be cooked, and ceramics can be fired. It doesn't generate that heat by burning stuff.
There are enough Hearths on the planet to sustain the population that the AI calculated would be manageable for the ecology. They are scattered throughout the tropical and temperate regions.
My question is - given that there is sufficiently advanced technology to do terraforming, shall I just say they tap into geothermal energy through a planet-wide grid, or is that scientifically laughable?
Additionally, I want these things to be massively durable, lasting for thousands of years without maintenance from the humans. Is that possible without the ongoing presence of the AI and a bunch of maintenance nanobots? Solar panels won't last that long.
Alternative solutions to the Hearth problems very welcome.
Assessments of the theory of the Utopian philanthropists not necessary - the validity of that theory is the subject of a series of at least nine books!