The Geothermal Ecosystem

Geothermal Energy—or Earth Heat—is a clean, abundant, and renewable natural resource that is helping us meet our environmental vision. Geothermal heat pumps can be installed almost anywhere and are an ideal way to heat and cool our homes, schools, and workplaces. Where Nature creates the right conditions, geothermal hot springs can provide energy for fish farms, greenhouses, and municipal heating systems. And in some places, deep geologic activity creates super hot water and steam that can be used by geothermal power plants to generate electricity for thousands of consumers.  All of these uses offer renewable energy with few environmental impacts.

40˚ to 70˚F Typical Ground Temperature 

90˚ to 200˚F “Hot Spring” Aquifer Temps

200˚ to 700˚F “Volcanic” Deep Resource Temps

Heating and Cooling Systems

Aquaculture, Greenhouses, Resorts, and Spas

Large Scale Power (Electricity) Generation

Ground-source geothermal heat is found everywhere just a few feet below the surface of the Earth. In a widely used installation method, geothermal—or ground-source—heat pumps (GSHPs) circulate water through a closed loop of plastic pipe (or refrigerant through copper tubing) that is inserted into vertical boreholes or laid out horizontally in relatively shallow trenches. The fluid discharges heat from a building into the ground during summer and taps the ground’s warmth during winter. GSHPs are among the most efficient technologies for heating and cooling buildings. Compared to conventional systems, GSHPs reduce the amount of energy used by homes and commercial buildings by 40% to 70% (including fossil fuels and power from the electric grid). They can also heat water for domestic use as a bonus. GSHP systems require little maintenance and provide reliable heating and cooling year-round. GSHPs use a small measure of electricity to move much greater volumes of renewable energy from the Earth to and from buildings. As a result, GSHPs deliver four to five times more energy to a home or commercial structure than the unit itself consumes from the power grid. Millions of GSHPs have been installed in the past 4 decades and provide an asset to the building owner with a ground heat exchanger that could easily last 50+ years. This underground heat source/heat sink is not dependent upon the outside are temperature, providing year-around comfort.

Uses for naturally occurring moderate-temperature waters have greatly expanded in modern times. In the United States, primary uses now include fish farming, greenhouses, spas and hot spring resorts as well as a variety of agricultural and industrial applications, such as crop drying, industrial food processing, and chemical manufacturing. District heating and cooling systems have been created where the resource is plentiful enough, and Thermal Energy Networks (TENs) have opened up further opportunities for district heating by operating at lower temperature differentials than traditional systems. Direct Use Geothermal (DUG) resources are usually found at economical drilling depths. They have few if any efficiency losses because their hot water resource is applied directly from the well to its purpose—like using heat to pasteurize dairy products. Equipment used for establishing Direct Use Geothermal projects, such as pumps and pipes, is standard and widely available. In general, the economics of Direct Use Geothermal projects are very good when careful consideration is given to their product/benefit/value vs. energy benefit and distance from market. In some parts of the country, geothermal springs and natural aquifers yield waters with wellness benefits directly from the Earth. From earliest times, people have used geothermal hot springs for bathing, cooking, healing, and heating.

Geothermal power production is the process of creating electricity from the Earth’s heat. In certain locations, nature’s natural geologic forces created deep and very hot geothermal fluid systems that are suitable for power plant development. Such systems, called Conventional Geothermal Systems, were the earliest to be tapped for power production, by using the naturally-occurring steam to drive a turbine. New technologies have opened additional opportunities for geothermal power in vastly more geographic locations. Engineered/Enhanced Geothermal Systems (EGS) use well stimulation to make subsurface rocks more permeable, which allows water to more easily flow through the rock and absorb heat. Advanced Geothermal Systems (AGS), also known as Closed-Loop Systems (CLS), don’t require a constant water source at all. Instead, they circulate a secondary fluid through a sealed pipe system, requiring no interaction between the subsurface environment and the liquid in the pipes. Supercritical Hot Rock (SHR) geothermal taps into reservoirs over 400 degrees Celsius by injecting water into the system, which causes the water to become heated to the point it becomes supercritical, thus allowing it to pass more easily through fractures. Successful geothermal power plants have proven to be highly stable and reliable (95+%) and provide electricity “24-7” compared to intermittent power generation facilities.

Learn More …

The International Ground Source Heat Pump Association (IGSHPA) focuses on training and standards for Ground Source Heat Pumps (GSHP), also called Geothermal Heat Pumps, GeoExchange Systems, Water-source Heat Pumps, and other industry terms. IGSHPA supports all types of geothermal energy. Learn about GSHPs.

The Geothermal Exchange Organization (GeoExchange) supports their members’ business objectives while promoting maximum, sustainable growth of the geothermal heat pump industry through Advocacy, Partnerships, Public Outreach, and Promotion of Quality Standards.

Geothermal Rising provides expertise through its members in geothermal power and direct use and supports geothermal energy of all types. The organization’s goals are to …

  • Broaden awareness of geothermal energy and its important role in the energy transformation.
  • Build positive public sentiment towards geothermal energy as a clean, renewable, and ubiquitous energy source.
  • Empower the geothermal community to advance through, technological innovation, education and collaboration with other sectors 
  • Expand the demand for and use of geothermal energy.