I question the rationality of anyone using the term "mother earth" in anything but a sneering sarcastic manner. Anthropomorphizing complex abstract systems such as the biosphere is a sign of mental handicap even more surely than praising God and talking in a hick accent.

Geothermal's economics haven't changed substantially in a very long time. Furthermore, it requires water as input, which automatically nullifies it as a serious contender.

It's the same reason why conversion of tar sands and oil shales isn't feasible as a large-scale project. Because water is an incredibly scarce and precious resource. And you can forget seawater since it's highly corrosive and would clog up the works with salt.

Heat pumps, yes. Geothermal, no.

Here's your handy cheat sheet:

• anything that uses biology is going to be expensive
  
• anything that uses freshwater is going to be impossible to scale
  
• anything that uses seawater is going to be destroyed
  
• anything that produces little, dilute or intermittent energy is not industrially sustainable (this includes wind)
  
• conservation means poverty, mass starvation and death

Trains, transit, district heating, heat pumps, are all excellent energy para-technologies. You'll notice that they fulfill all of the criteria set above. But none of them qualify as a source of primary energy. And what's the only source of energy that fulfills all of the above criteria? You have 1 guess because this one's easy.