The Earth itself is a fascinating machine. There are so many systems and functions at work every second of every day that nobody could know all of them. While humans and some opportunistic apes in Japan have enjoyed hot springs for generations, we recently discovered the other benefits and uses of the Earth’s natural geothermal heating. Far below the ground is an endless “ocean” of magma and molten rock, under immense pressures and supporting the mantle. The mantle is a layer of mostly solid rock that moves like a liquid. Geothermal systems dig toward the mantle, and things heat up very fast. What can we do with all that heat, though?
One of the most attractive applications for the power locked in Earth’s inner heat is electricity generation. While we can neither create nor destroy energy, we can change its form. To access the power of heat to generate electricity, a well is dug up to two miles into the Earth. It pumps hot water warmed by the heat conducting up through the mantle into the crust. A pump draws this water higher and higher, and eventually, the system reduces the pressure exerted on the water, and steam is allowed to escape as the water expands in the lower pressure environment. This steam turns a turbine which powers a generator and produces electricity. The steam then condenses when it cools, where it returns to the Earth and other injection wells pump it out.
Geothermal energy can be a very effective means of generating power under the right conditions. Places like the Philippines and Iceland get nearly a third of their electrical needs from geothermal energy! This isn’t anything new, outside of the equipment used. Native Americans have been using geothermal energy for nearly ten thousand years for cooking. The Greeks and Romans used geothermal energy for their baths. However, the first practical, modern use of geothermal energy dates back to 1904 in Italy, where the world’s second-largest geothermal power plant still stands today. Closer to home, though, there is a more down-to-earth use for geothermal energy.
With all that hot water locked in the Earth’s crust, it would be easy to assume that geothermal is only suitable for warming things up. However, while it is true that a heat pump can present an easy way to heat your home in the colder months, these heat pumps can also operate in reverse to cool your home during the summer season. This is because water absorbs heat both in the Earth and in your home, and you can harness it with open or closed-loop systems.
Open-loop systems are often in buildings with several occupants. They draw water from geothermal wells into the heat pump and then either reenter the well or enter another water system. These are the cheaper of the two options but require a consistent flow of water.
Closed-loop systems draw hot water through loops of pipes in the geothermal well, and in the cold months, when the water underground is warmer than the air above, hot water is drawn upward and distributed into the home. Meanwhile, the process reverses with cold water drawn into the pipes and with the cool air drawn into compressors and redistributed throughout the house in the summer.
Geothermal heating is one of the few methods of generating energy and electricity that will never go away. It isn’t just renewable – it is inexhaustible, and will last as long as the Earth does. This type of energy is clean, reliable, and represents a worthy long-term investment as populations rise and the need to heat, cool, and power our homes increases.