7 Facts on Geothermal Energy and Water’s Relationship
January 27, 2017
Geothermal energy relies on heat from the Earth to provide power. In many cases, it also relies on water to carry that heat. Water is vital to every aspect of geothermal generation, often in ways that people don’t expect.
Geothermal power plants use water to carry the Earth’s energy to the surface. Water is pumped down into the ground until it is hot enough to boil. The steam rises up through a shaft, where it powers a turbine to generate electricity. It cools as it rises, which eventually allows it to condense and be used in the cycle again.
Geothermal heat pumps also use water to carry heat, but in a very different way. These systems circulate water between a home and the ground. Underground areas have a constant temperature regardless of the season, whereas the water’s temperature will vary based on the weather. When it is hot, the water cools when it goes underground. When it is cold, it warms up. When it flows back to the building, the water heats or cools it at a minimal energy cost.
Finding Geothermal Activity
Some places have more geothermal power than others, and water is one of the best ways to find it. Geysers are among the most visible signs of geothermal activity, so they can indicate potential sources of power without extensive and costly surveying.
Geothermal power is not a new technology. Ancient cultures, including the Romans and the Japanese, often used it to heat water. They built bath houses at the site of natural hot springs to harness the power of the Earth’s energy. These sites were poorly understood at the time, so they often gained religious significance among ancient people.
All power plants, including geothermal plants, need coolants to stay functional. Water is one of the cheapest, cleanest, most effective options, so many plants use it to keep their equipment at a safe temperature. It isn’t universal, but it is common, and even plants that don’t rely on it exclusively often combine it with other cooling methods.
Water plays a role in the construction of geothermal plants. Building a plant involves digging a deep shaft into the ground, and that often requires dust suppression and drilling fluid. Water fulfills both of these needs at a low price, with minimal impact on the environment.
While geothermal plants pump most of the water that they extract back into the ground, some of it is lost as steam. That water needs to be replaced, but very few plants use clean water to do so. Most of the water that comes out of the ground at these plants contains a variety of minerals and other contaminants, so it is usually safe to replace those fluids with wastewater. This provides a use for water that would otherwise need to be purified before being utilized for other purposes.