Geothermal Energy: Types And Processes


If we dig a hole deeper into the earth, the temperature will rise as we go deep. It occurs because the earth’s core is incredibly hot (10,800 F). The heat radiates in all directions from the core, raising the temperatures of the Earth’s surrounding layers.

Geothermal energy refers to the heat (thermal) energy that comes from Earth’s core and is stored in its layers. The temperatures beneath the surface are used to heat and cool above the surface.  

Is Geothermal Energy Renewable Or Non-Renewable?

Geothermal energy is a renewable source of energy, given that the Earth’s core radiates heat all the time. Heat radiates from the Earth’s core into its layers. 

The core temperature is currently around 5000K, down 250K from when the Solar system was formed 4.5 billion years ago. Therefore, if the temperature continues to decrease at its current rate of 55 degrees every billion years, it will need more than 90 billion years for the Earth’s core to fall to 0 degrees Kelvin, the temperature at which no life can survive.

Benefits Of Geothermal Energy

Geothermal energy is cheaper than other forms of renewable energy over the long run. It contributes to financial savings by reducing your heating and cooling expenditures by up to 70%. Additionally, many countries offer tax benefits for those who install and use geothermal energy.

One of the primary benefits of geothermal energy is its extremely low carbon footprint, as it derives its heat from natural sources. It contributes to the environment-friendly process; however, there is a catch.

While geothermal power plants do not need electricity to run, geothermal heat-source pumps for residential and commercial use do require some electricity to function. In the case of non-renewable sources of electricity, there would be a small carbon footprint.

Heat-source pumps are both eco-friendly and quiet because they do not use internal combustion motors like generators. It helps to prevent noise pollution.

A heat source pump powered by geothermal energy can last up to 20 years, while geothermal power plants can operate for 30 years with optimum efficiency. We’ve discussed both of them below!

Geothermal Power Plants

Geothermal power plants do not require the combustion of fossil fuels to operate. They utilize renewable resources like natural hot water streambeds. Geothermal power plants are classified into three types. They all generate electricity, but in slightly different ways.

Dry-Steam Power Plant

They are the most common type, with more than half of the geothermal power plants around the world running on dry steam. The underground heat reservoirs allow the plant to pump hot steam into turbines, which spin and this process then turns on the generator to produce electricity.

After the steam is used to power the turbines, it condenses into the water. Water is injected back into the ground to reheat it.

Flash-Steam Power Plant

The process of this type of plant is similar to that of dry steam power plants. It involves pumping hot water instead of steam. The plant pumps high-pressure hot water from the ground and stores it in an above-ground flash tank. The flash tanks are set at lower temperatures, causing the hot water to turn into steam quickly.

Turbines are powered by the steam generated afterward. After cooling down, the steam condenses into water, pumped back into the ground through the injection well.

Binary Cycle Power Plant

Binary cycle power plants differ from other power plants because they don’t directly contact the turbines with water or steam which is pumped from underneath the ground.

Pumped water from geothermal reservoirs is routed through a heat exchanger that heats a second liquid. When the second liquid is heated, steam is produced, turning the turbines and powering the generator.

Injection wells recycle water into the ground, while the second liquid is pumped into the turbine and then sent to the heat exchanger for a second round of heating to carry on the process. 

Geothermal Heat Pumps

In most cases, geothermal heat pumps are placed in residential areas. When you install a geothermal heat pump to power your home, you will be able to utilize ground temperatures to cool (in the summer) or heat your home (in the winter) 

The temperature above the ground varies with the seasons; however, the temperature below the ground remains constant at 50F-60F regardless of the season. It ensures that the heating pumps can function efficiently all year long, without interruptions.

The heat-source pumps consist of four different types, including one open-loop system and three closed-loop systems. All of them are somewhat different and are installed based on factors including climate and soil conditions and the amount of space available.

Closed-Loop Systems

Closed-loop systems are classified into horizontal, vertical, and pond/lake systems. They all function the same way. 

Generally, horizontal systems are installed in residential areas due to low setup costs. You can opt for a closed-loop vertical system that reaches as deep as 400 feet beneath the surface for large commercial buildings. The cheapest closed-loop systems are those built under lakes and ponds.

Typically, closed-loop systems use ethylene glycol and water as a mixture that passes through underground pipes which come up to connect with the building’s heat exchanger. A warm mixture is pumped from underground in the winter and a cool mixture in the summer. Heat is exchanged between the water and ventilation air using the heat exchanger, which results in cooling or heating the building. 

Closed-loop systems keep the indoor temperature moderate, so you’re well covered no matter the season!

Open-Loop Systems

This system works by bringing water directly from an open source to the heat pump. There are two options to deal with the water after it reaches that point: either recycle it back or pump the water to another body without causing any pollution. Since the water temperature does not differ greatly, you need more volume to transfer heat efficiently.

They can be very low-cost; however, they require a steady flow of water in good volume to function properly.

The constant temperature underground makes open-loop systems suitable for use worldwide. But the cost and efficiency of each will differ. 

It is possible for geothermal energy to last as long as the earth itself. Therefore, we should consider it as a gift and promote the use of geothermal energy.

Would you like to know the pros and cons of biofuels? Read our blog to find out. 


Please enter your comment!
Please enter your name here