There are three types of geothermal energy:
•    Geothermal power plants that produce electricity
•    Direct use and direct heating systems
•    Geothermal heat pumps
Let’s explore each of these exciting natural possibilities. Why? So, we can use the earth to save the earth.

Across the United States and around the world, there are reservoirs of hot water. This water can be found near the earth’s surface, or deeper down. The water is extremely hot, with temperatures ranging from 300° to 700°F. Geothermal power plants use the steam from the hot water to produce electricity.

It’s a simple process. The steam creates energy that rotates a turbine. The turbine activates a generator and electricity is produced. And this is a natural resource, so we’re using these reservoirs in the earth to power the earth.

Geothermal power plants are built where the reservoirs of hot water are located. In the U.S., most of the reservoirs are in the western states, but there are also reservoirs in the South, Midwest, and East Coast. This means that we can be using this natural resource more than we are currently.

And scientists and engineers are working on innovative technologies that will allow geothermal power plants to be built anywhere around the world, serving clean and renewable electricity at any time!

There’s another kind of geothermal energy that’s readily available called geothermal direct heat. It’s a simple process: direct heat comes from the water found in rock beneath the earth’s surface. The hot water in the rock reservoirs produces heat and steam, but isn’t hot enough to be economical to generate electricity. This water is captured and piped into buildings to provide heat, melt ice on roads and sidewalks, and warm fishing farms, greenhouses, and swimming pools.

Direct heat systems are already in use all around the world to make our lives better. For example, direct heat systems provide heat for most of the buildings in Reykjavik, Iceland. Direct heat is also used for food dehydration, pasteurizing milk, and mining gold. It’s an easily accessible and effective geothermal energy source.             

Finally, there are geothermal heat pumps. These heat pumps work by using the heat that naturally occurs in the ground. Did you know that temperatures in the earth 10 feet below ground range from 50°F to 60°F. This means that soil temperatures are typically warmer in the winter and cooler in the summer than the air. Geothermal heat pumps use the earth’s temperature to heat and cool buildings. How? During the winter, heat pumps take the heat from the ground into buildings. The process is and reversed during the summer.

According to the U.S. Environmental Protection Agency (EPA), “geothermal heat pumps are the most energy-efficient, environmentally clean, and cost-effective systems for heating and cooling buildings. All types of buildings, including homes, office buildings, schools, and hospitals, can use geothermal heat pumps.” In addition to heating and cooling buildings, geothermal heat pumps can provide hot water. Best of all, this is clean, renewable energy.

As demand for energy increases, geothermal energy will become an increasingly important energy source.  Right now, California has 43 operating geothermal generating plants, and plans to build more. A 2019 U.S. Department of Energy (DOE) report, GeoVision: Harnessing the Heat Beneath Our Feet, says, “generating electricity through geothermal methods could increase 26-fold by 2050, providing 8.5 percent of the United States’ electricity, as well as direct heat.” And, in Boise, Idaho, geothermal energy is heating 92 of biggest buildings in the city.

Let’s all embrace geothermal energy: a clean, green, renewable energy that uses the earth to power the earth.

https://www.eia.gov/energyexplained/geothermal/geothermal-heat-pumps.php

https://www.eia.gov/energyexplained/geothermal/use-of-geothermal-energy.php

https://www.go-gba.org/resources/green-building-methods/geothermal-energy/

https://www.energy.gov/eere/geothermal/electricity-generation

https://e360.yale.edu/features/can-geothermal-power-play-a-key-role-in-the-energy-transition

https://www.energy.gov/eere/geothermal/downloads/geovision-harnessing-heat-beneath-our-feet

Many commercial and residential complexes use cooling towers to effectively aid in cooling.  An average public high school’s* cooling tower uses about 30,000 gallons of fresh water per day when it’s hot outside. That’s enough to fill a good sized back-yard swimming pool. Twice. 

A major airport can consume close to a million gallons of fresh water on a hot summer day, just for cooling tower operations. It’s great that we are honoring watering restrictions, fixing drips in faucets and leaky toilet valves; however there are billions of gallons of fresh water being evaporated and discharged into the sewer from cooling towers every day.

Cooling towers use the process of evaporative cooling to increase the energy efficiency of the air-conditioning equipment that serves the building. In the process, a lot of water is evaporated, and nearly as much more is flushed down the drain to purge out impurities.

The US had about 81 billion square feet of commercial space in 2010, served by 300 million tons of cooling capacity (based on floor space estimates from DOE report). This represents between 5-billion and 15-billion gallons of fresh water consumption each day.

Industry has begun to embrace geothermal (elimination of cooling towers) for all the right reasons:

• Elimination of water consumption associated with cooling towers
• Elimination of tower related noise
• Elimination of chemical treatment for cooling towers
• Reduction in annual maintenance costs for HVAC system
• Storm proofing through elimination of outdoor equipment (the cooling tower)
• Impressive federal tax incentives
• Reduced capital expenditures for regular cooling tower replacement

The advantages that can be cited that make a geothermal sourced building more sustainable are many. With a reduction of water consumption (which can be close to half of all the freshwater consumed by a building), your client is saving money and doing a good thing for the environment.

Cooling towers can be rather noisy, and most will agree that elimination of this outside noise would be of benefit to both the public and occupants of the building.

Geothermal sourced chiller plants and heat pumps are more efficient by design, because the condenser water is cooler than can be supplied from an evaporative cooling tower, increasing the EER (Energy Efficiency Rating) substantially.

The average life of a chiller is about three decades, and most chiller plants live through two or three cooling tower replacements. With the geothermal source, these expensive planned expenses go away.

By placing a chiller plant, or any cooling tower-sourced building using water source air-conditioners/heat pumps on a geothermal source, you have created an entirely geothermal sourced building, making the entire building’s HVAC system eligible for federal tax credits. This means that when upgrading chillers and water sourced heat pump, they may be eligible for the current tax credits for geothermal systems.

Most regions of the country and the world have storm events periodically such as hurricanes, tornadoes, blizzards, etc. These storm related events can destroy outside equipment. Many insurance companies will provide credits for elimination of this equipment. The New York Times said, “Geothermal Systems Arise as a Storm-Proof Resource”.  Additionally, outside equipment often needs to be winterized, and properly installed geothermal sources may save you these seasonal costs and headaches.

The federal government gives a 10% federal tax credit, and five year depreciation through the Maximum Accelerated Cost Reduction System (MACRS) on commercial geothermal systems.  With 50% bonus depreciation the first year, a $1 million upgrade can net federal tax incentives amounting to 48% of the entire cost, or federal tax incentives of $480,000.

The USGS says that the average American uses 80 to 100 gallons of water each day.   Cooling towers use as much fresh water as 50,000,000 US residents each day. I think that California could put that water to good use. This is in the neighborhood of 20% of the volume of water that flows over Niagara Falls each day (65 Billion gallons of water flow over Niagara Falls each day).

*based on national average of 752 students per high school, 2000 https://nces.ed.gov/pubs2001/overview/table05.asp 

With all the air conditioning needed in the summertime, why would a winter time freeze cause the electrical grid to “spike” out of control as we saw in Texas? Most people know that air conditioning loads in the middle of August usually drive the greatest demand on the grid. However, electric heaters, often used to handle peak heating loads, can double or triple the peak in the wintertime.

Energy Facts:

• 1 watt of electricity = 3.412 BTUs
• I kW of heat consumed by an electric heater = 3,412 BTUs of heat
• I kW of heat consumed by an electric Heat Pump = 17,060 BTUs of heat*
• It takes 20% the kW to do the same heating with a heat pump *(@5.0COP)

As it gets colder outside, Air Source Heat Pumps lose efficiency. Geothermal Heat Pumps continue high efficiency operation regardless of outdoor temperature.

Cold temperatures can reduce efficiency of heat pumps, simply because it's hard to extract heat from outside air as it gets colder. The efficiency of air source heat pumps drops as it gets colder outside, just as the gas mileage efficiency of a car drops when it’s climbing a mountain road. Geothermal heat pumps are not subject to drastic temperature fluctuations, because they're coupled to the temperature in the shallow earth, which ranges between about 45 and 75 degrees in the US.

As you look at the efficiencies of heat pumps at the ASHRAE building in Atlanta, you can see that air source heat pumps are closer to geothermal heat pumps efficiency in the summertime, but in the winter time, when heating is needed most, the air source heat pumps are using much more electricity that geothermal by comparison. Geothermal clearly reduces peak electrical demand on the grid, eliminating problems like Texas experienced this winter.

Wintertime electrical peak load management is a well-known challenge as Northeastern states make the transition to total building-stock electrification. New York is eliminating combustion heating of all types in buildings (as is stipulated in the New York State’s Climate Leadership and Community Protection Act (CLCPA). As they make that transition, competent studies have proven that Geothermal Heat Pumps must play an integral role in Beneficial Electrification in order to manage peak electrical load in the coming decades.

Ontario completed a study at the end of 2020 that gives a 30 year roadmap to managing electrical grid spikes through the implementation of geothermal heat pumps. In the image, we can see the savings in reduction of fossil fuels, the cost for implementation of air source heat pumps, the cost for implementation of geothermal heat pumps, and at the far right is that Ontario will save half-a-trillion dollars on electrical grid modifications by choosing the geothermal solution. The reason is simple. Winter time peak loads are leveled through the implementation of geothermal heat pumps.

When I started in the GHP industry in 1990, I was asked by a reporter what the future held for the industry. I said that while excavation and drilling are required now for the systems, the day would come when geothermal pipelines would be worked into the infrastructure of communities. This is the place at which we find ourselves today. 

Read more about geothermal grids in “New Contractor Opportunities with Geothermal Districts”

Read more Beneficial Electrification in “The Integral Role of Geothermal Heat Pumps in Beneficial Electrification”

Jay Egg is a geothermal consultant, speaker, writer, and the owner of EggGeothermal. He has co-authored two textbooks on geothermal HVAC systems published by McGraw-Hill Professional. He can be reached at jayegg.geo@gmail.com.
©Egg Geo, LLC 2021