Geothermal energy is not commonly used due to its high upfront cost and limited availability. Geothermal systems require a large amount of energy to install, as they require a deep well to be drilled in order to access the geothermal energy source. Additionally, geothermal energy is only available in certain areas, as it relies on the presence of underground hot water or steam. As a result, geothermal energy is not a viable option for many homeowners and businesses. Despite its high upfront cost and limited availability, geothermal energy is a reliable and efficient energy source that can provide long-term savings.