Travel with us through the depths of the Earth as we explore a possible future energy source! The Earth has, broadly speaking, four distinct layers including the solid crust we live on, the mostly solid mantle, liquid outer core, and the solid inner core. Each of these layers maintains general temperatures, increasing with depth. This heat comes from the friction of denser material sinking to the center, the decay of radioactive elements, and a reserve of heat from when the planet first formed. Hottest of all the layers is the core, inner and outer, reaching roughly 10,800 F or 6,000 C. We’re talking surface of the sun hot. This heat, coupled with the spin of the Earth, is how our magnetic field is generated. Geothermal energy relies on these increasing temperatures to provide a renewable and inexhaustible energy alternative to coal and natural gas.
This natural source of heat has been used for centuries in various cultures around the globe. Hot springs have been used for spas by the ancient Greeks and Romans, medical purposes and cooking by the Maoris in New Zealand, even buildings were heated by the inhabitants of Pompeii before Mount Vesuvius blew. Today, reservoirs are tested for potential, then drilled to be brought to the surface so it can be converted to electricity by geothermal power plants.
As with all alternative options, there are pros and cons to geothermal energy. In comparison to coal and fossil fuels, the footprint is minimal, but the reservoirs can contain arsenic, boron, and mercury, and can emit greenhouse gasses that are generally trapped below the Earth’s surface. Regardless, it is a vast improvement over current energy sources. This heat will last billions of years according to scientists, meaning this energy source is not only considered a renewable resource, but is also reliable with a predictable output that is generally preferred over solar power. Unfortunately, upfront cost of geothermal systems are very expensive, as well as drilling reservoirs, which can cost up to $7 million. Additionally, not all places are a hot bed for reservoirs, and when hot water has to travel, you lose out on a lot of energy.
All in all, geothermal energy holds huge promise, and, like most up and coming clean alternatives, a lot of its future potential relies on technological developments of the future.