The main disadvantages of geothermal energy are:
- High initial economic cost.
- Geothermal power plants increase the risk of an earthquake.
- The performance depends on the location of the installation.
- Consequences on the environment.
Geothermal energy is a new technology and less well-known than other sources of renewable energy (solar energy, hydraulic energy or wind energy) or non-renewable energy (fossil fuels or nuclear energy).
The advantages of geothermal energy are numerous, but there are also certain disadvantages to consider.
High initial cost
The main disadvantage of geothermal energy is the initial cost to extract it. Precisely by its own nature it is necessary to extract it from the underground.
This process implies that the first phases of the project are long and costly economically. The cost of drilling holes in the ground, installing heat exchangers, etc. It is much more expensive than installing a natural gas boiler or installing a solar panel.
To carry out a project for a geothermal energy installation, it is necessary to carry out previous studies. These studies require specific machinery and significant investments in the initial phase of the project.
Geothermal power plants increase earthquake risk
The construction of geothermal power plants can affect the stability of the earth. In fact, geothermal power plants have caused a subsidence (movement of the earth's surface) in both Germany and New Zealand.
Earthquakes can be triggered by hydraulic fracturing, which is an intrinsic part of power plant development of the improved geothermal system.
Why does the earthquake risk increase?
The goal of an improved geothermal system is to create a hot rock fracture network that is otherwise too impervious for water to flow. If you can create that fracture network, you can use two wells to create a heat exchanger. You pump cold water through one, the Earth heats it and you draw hot water through the other end.
Operators drilling a geothermal well cover it with a steel tube using the same process and technology used to build an oil well. A section of bare rock is left open at the bottom of the well. They pump water into the well at high pressure, forcing existing fractures to open or creating new ones.
Sometimes these small fractures cause small earthquakes. The problem is when earthquakes get too big.
Installation location affects performance
Despite the fact that the heat inside the Earth's layers is present everywhere, it cannot be used equally in all places. There is no possibility of exploiting this energy source everywhere.
Its operating principle is based on the use of heat inside the Earth. One of the most used techniques to take advantage of the internal energy of the rocks is constructing wells of about 150 meters through which a fluid circulates. The fluid drops at a low temperature, at the bottom it is heated by a thermodynamic process and rises with the thermal energy acquired to the surface.
Depending on the geological characteristics, some places are better than others for the construction of geothermal wells. Rocky terrain, for example, is a great disadvantage for the construction of geothermal facilities. On the other hand, lands where there are hot springs are much more favorable.
In the case of large cities, the construction of geothermal power plants is more difficult. The main disadvantage, in many cases, is that in the cities the subsoil belongs to the city council and is occupied by other services such as sewage, gas and electricity pipes, etc.
Only local exploitation. It cannot be transported as a primary source of heat, it must be consumed in the same place where it comes from. On the other hand, in geothermal power plants this drawback disappears since electricity can be transported.
What effects does geothermal energy have on the environment?
In terms of the environment, geothermal energy can emit toxic emissions.
There are a large number of greenhouse gases below the earth's surface, some of which are mitigated to the surface and to the atmosphere. These emissions tend to be higher near geothermal power plants.
In the event of an accident or leak, in certain places, hydrogen sulfide can be released, which is detected by its rotten egg odor, but which in large quantities is not perceived and is lethal. In those cases there would also be a certain risk that toxic substances, such as arsenic, ammonia, etc., will be released and contaminate nearby waters.
One of the main disadvantages of geothermal energy in the field of large geothermal installations is the deterioration of the landscape because in order to exploit this type of energy, it is necessary to drill the earth's surface. This disadvantage of geothermal energy, in the case of single-family houses, the environmental impact is practically imperceptible.
However, geothermal energy is a type of renewable energy. It is considered renewable energy because it does not consume resources and is practically inexhaustible.
Regardless of these toxic emissions, the pollution associated with geothermal power is nowhere near what we see with coal power and fossil fuels.