Geothermal Heating & Cooling: The Basics
For a long time, the idea that an untapped wealth of energy existed just beneath our feet that is renewable and cutting-edge science fiction seemed just around the corner. Geothermal energy (the heat that resides deep in the Earth) has been a mainstay of science fiction and (more recently) renewable energy. Caves have been a source of warmth in winter because their deeper systems have a regular temperature that stays the same year-round. If only we could take advantage of this temperature regulation for ourselves.
How It Works
As it turns out, we can take advantage of geothermal energy to heat and cool our own homes. The best part is, all it takes is existing technology and a little digging.
First, a little bit of background on heating and cooling systems. We don’t actually create cold. Refrigeration technology is simply a process of moving heat from one place to another, following the laws of thermodynamics. Heat energy does its best to equalize in a room, moving energy from a higher source to a lower source to balance things. Refrigeration introduces something that’s a lower temperature – in the case of air conditioners, pressurizing a refrigerant liquid creates the cooler substance – so that the warmer air will work to equalize the two temperatures.
By constantly moving a cooler substance into a warm room, the heat in the room cannot keep up and will eventually normalize to the temperature of the cooling substance. With geothermal climate controls, we’re doing the same thing, but we use the Earth as a heat exchanger. Rather than needing to burn fuel during the winter, or compress toxic refrigerants, pumping water into the ground can deliver all of the control you need.
Heat in the Winter, Cold in the Summer
Depending on where you live on the Earth, the temperature 20 feet into the Earth ranges from 50 to 60 °F. That’s cooler than summer temperatures and warmer than winter temperatures. It also stays at this temperature year-round, even during heavy blizzards.
Geothermal pumping systems bury multiple loops of water pipe beneath your home (the loops save on distance and help to increase surface area, allowing water to be moved quickly without temperature losses). Water is then forced through the system, down into the Earth’s crust.
During the summer, cool water is piped through the home, similar to how a refrigerant is pushed into an evaporator, and warm air is moved over the pipes. As the air moves, heat is transferred to the cooler water and the temperature equalize. Cool air is then forced into the home, replaced by the warmer air. The now warmed water is pumped down into the Earth, where it cools off. After the water cools, it’s pumped back up into the home to repeat the process.
This same process is used during the winter but has the opposite effect. As the water is pushed through the coils or piping in the home’s floor, it cools, releasing heat into the home. The cooled water flows down into the Earth, where ground temperature heat the water before it’s returned to the home. Geothermal heaters function in a way that’s similar to a boiler and hot water radiator system. In fact, some of these systems can double as an effective method for generating hot water for your home. Combination systems need to be carefully balanced, however, as a hot water tank that falls beneath 50° F can become a health hazard (stored water needs to be kept heated to kill off potential bacteria).
As you can see, the internal temperature of the Earth, since it’s cooler than summer and warmer than winter, functions as a year-round heat pump without the high energy costs or toxic refrigerants. The next time you want to upgrade your home’s heating and cooling system, consider installing a geothermal system for year-round climate control!
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