Geothermal (ground-source) Heat Pump

The geothermal (ground-source) heat pump (GHP) is one of the fastest-growing renewable energy applications in the world. GHP has seen a 10% annual growth in about 30 countries over the past 10 years. Since it works with groundwater between 5℃ and 30℃, it can be used in every country in the world. 

Much of this growth has been taking place in the United States and Europe, but even countries like Japan and Turkey seem to be taking interest.

About 12,000 MWt (thermal) of power is currently installed worldwide, and about 72,000 TJ of energy is used each year (20,000 GWh). People have installed approximately 1,100,000 GSHP units worldwide, but the data is not complete, so it is hard to say how many people have them. 

Geothermal (ground-source) Heat Pumps

Geothermal energy has made it possible for many people to heat and cool their homes during winters, thereby also making hot water available all year round.

Geothermal heat pumps are sometimes combined with solar heating systems since they work more efficiently than a single system alone. Geothermal heat pumps are also known as earth energy systems, ground source heat pumps, geo-exchange, and earth-coupled. They can also be called geothermal heat pumps. These names differ from one area to the next.

They are called ground source heat pumps and geo-exchange to avoid confusing them with conventional geothermal power systems, which take hot water from several feet below the surface to generate electricity.

People who use geothermal heat pumps get this energy from under the ground and use it to heat and cool buildings/homes. The technology of geothermal heat pumps has been in use since the 1940s. 

Working of Geothermal Heat Pump

The geothermal heat pump system comprises three main parts: the heat pump unit, the ground heat exchanger, and the air delivery system or ductwork. These three parts work together to heat and cool homes.

The heat exchanger is made up of a loop of pipes buried a few feet under the ground near the building. These pipes essentially transfer the heat from one place to another. A mixture of water and antifreeze flows through a series of lines to get heat from the ground or out of the Earth. Antifreeze solutions are usually added to the fluid to keep it from freezing in the winter.

The functioning of the geothermal heat pump is very similar to a refrigerator.

A fridge in keeping the food stored inside cold, emits heat making the area around the refrigerator much warmer.

During winters the geothermal heat pump gets hot water or gas from the ground heat exchanger and sends it to the building’s air transfer system, which keeps the house warm.

During summers, the cycle is different. The geothermal heat pump takes heat from the air inside the building and moves it to the ground heat exchanger which cools it.

Types of Geothermal Heat Pumps

The four main categories of geothermal heat pumps are as follows:

Closed-loop systems

They are made of thick plastic loops that allow liquid to move through them. Some closed loops are buried several feet below the ground or submerged in water. These systems have a heat exchanger that coordinates the exchange between the refrigerant, fluid, and a heat pump in the closed loop.

Pond or lake system

Most homes have a pond or lake near them. These water bodies can be used for a closed system to be set up under them. 

Open-loop systems

This type of geothermal heat pump is best for people with enough groundwater to run it. The groundwater is used as a heat exchanger, and the whole system moves through it. In a surface recharge process, it goes back down into the ground. People who want to buy an open-loop geothermal heat pump should have enough clean groundwater because this is a local code and regulation.

Hybrid systems

A hybrid system brings together geothermal and air source heat pumps to make an affordable and efficient system. There are times when cooling takes the lead because of internal gains when setting up heating and cooling loads isn’t balanced. Instead of increasing the size of the heat exchanger to meet a higher cooling load, it is remodelled to meet the heating load, and a heat rejector is added to the system to manage the excessive heat generated. If you want to get rid of boilers and fossil fuels, hybrid systems are a good choice. They use less land and money to set up the ground heat exchanger.

Conclusion

A heat pump can provide both heating and cooling by taking advantage of the stable temperatures in the Earth. As such a GHP is the most energy-efficient renewable technology. There are two types of GHP systems that can be built either vertically or horizontally, and they depend on the kind of rock and soil where the system is built.