Originally Posted By: paul
your going to have a really hard time raising the underground temperature to 100 degrees F.


That's because the ground is cooled during the nighttime (near the surface) and during the winter deeper down. If you check it in the daytime it's still cold from the night before, but check the same point at night and you might find it's hotter than during the day.

So you could gain something, but it won't be as cold as it is now unless the nights and winters are even colder. You could improve it further by going deeper with time as the cold region moves downwards, then coming back to the surface during the night/winter.