<p>Actually, geothermal is available from any point on Earth. It is literally everywhere. You simply need to drill a hole deep enough. But half the cost is in the drilling, so that’s obviously the central technology that needs improvement. Naturally, it is cheaper where you don’t have to go as deep. Geothermal has been used since ancient times (hot springs). For home use, depending on the system and whether it is used for heating or power generation, depths of only 1 meter to 150 meters suffice. A well can last a century without regeneration. Unlike wind or solar, it is available 24 hours a day.</p>