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Geothermal energy is often touted as a sustainable alternative to fossil fuels. However, it still makes up only a small fraction of total energy sourced from renewable sources. It has failed to catch on like solar and wind energy, and there are several reasons why geothermal is not as popular as solar or wind.
- The first is that it requires a high initial investment to extract geothermal energy compared to other green energy sources.
- Second, there are only limited locations where geothermal energy can be harvested.
- Third, most optimal sites for geothermal energy are in geologically active areas, which means there is always a risk of earthquakes.
- How Is Geothermal Energy Generated?
- How Is Geothermal Energy Used?
- Is Geothermal Energy Expensive?
- Is Geothermal Energy Renewable?
- Disadvantages of Geothermal Energy
- Is Geothermal Energy Safe For The Environment?
- What Are The Pros And Cons Of Geothermal Energy?
- What Are 3 Disadvantages Of Geothermal Energy?
- What Is The Biggest Problem With Geothermal Energy?
- Why Is Geothermal Energy Not Available Everywhere?
- Can Geothermal Be Overused?
How Is Geothermal Energy Generated?
Geothermal energy is generated when steam from underground reservoirs is used to produce electricity. This steam is used to rotate a turbine, which activates a generator that produces electricity. The three main types of geothermal power plants are:
A dream steam plan draws steam from deep in the ground. This steam is piped into the plant where it is used to turn a turbine.
A Flash Steam plant is the most common type of geothermal plant in the world. It uses geothermal water reservoirs that have a temperature of greater than 360 degrees Fahrenheit. This superheated water flows up to the surface under its own pressure.
As it gets nearer the surface, its pressure drops, and some of the hot water turns into steam. The steam is used to turn the turbine and the rest of the water is injected back into the ground.
A binary steam plant uses water at a lower temperature of 225-360 degrees Fahrenheit. This type of plant uses the heat from the hot water to boil a working fluid, which is often an organic compound with a low boiling point.
The working fluid turns into steam via a heat exchanger and is used to turn the turbine. The hot water is injected back into the ground to be heated again.
How Is Geothermal Energy Used?
There are several uses for geothermal energy. These are:
Direct Use and District Heating
The hot water from hot springs has been used in ancient and modern times for cooking, taking relaxing baths, and heating. Today, many people still believe that bathing in hot springs offers some health benefits.
Geothermal energy is also used in district heating for multiple buildings. Hot water is piped from underground reservoirs into buildings where it provides heating. In Reykjavik, the capital city of Iceland, most buildings are heated using water from geothermal springs.
Geothermal energy is used in industrial applications for food dehydration, gold mining, and pasteurizing milk.
Generating electricity using geothermal energy is the most modern use of this energy. It requires water or steam at temperatures of 300 to 700 degrees Fahrenheit. Geothermal electricity plants are usually built close to the geothermal reservoirs.
Geothermal Heat Pumps
Geothermal heat pumps use the constant temperature near the earth’s surface to heat and cool buildings. Heat pumps move heat from the ground into a building during winter and vice versa during the summer.
Is Geothermal Energy Expensive?
The cost of geothermal power is heavily weighted to the initial installation cost, instead of the fuel to keep installations running. Drilling wells and laying pipelines occur first, followed by resource analysis. After that, the actual plant is built.
In the US, the initial cost is around $2500 per kW and up to $5000 per kW for a small plant of less than 1 MW capacity. Operating costs are $0.01 to $0.03 per kWh. Most of the geothermal plants in operation today operate at a rate of over 90% availability.
However, running at 98% capacity can increase maintenance costs. Pricing the electricity higher justifies running a plant 98% of the time since the higher maintenance costs can be recovered.
Is Geothermal Energy Renewable?
Geothermal energy is considered a renewable and sustainable source of energy. The reason for this is that it is sourced from deep in the earth, which contains an unlimited amount of heat energy. Even in areas where geothermal energy generation depends on a reservoir of water; the water taken out can be injected back into the well, which makes it sustainable.
Disadvantages of Geothermal Energy
While geothermal energy is widely praised for being a clean source of energy, it does have some downsides. Here are some of the disadvantages that come with using geothermal energy.
Extracting geothermal energy does cause some greenhouse gas emissions during the extraction of steam. For instance, hydrogen sulfide, methane, and ammonia are often released in the process of extracting geothermal power. However, the amounts are still significantly lower than with fossil fuels.
Possibility of Depletion
While geothermal is thought to be sustainable and renewable, some locations are at risk of depletion as they cool over time. The only non-depletable source of geothermal power is magma. However, the technology for extracting geothermal energy from magma is still in development.
High Initial Cost
Another important consideration is that most geothermal resources require a high initial cost to be extracted. Drilling and installing a complex system to extract geothermal energy is not cheap. However, the return on investment is often within 2 to 10 years.
Huge Land Requirements
Depending on the type of geothermal energy, the land requirements are huge. For instance, installing a geothermal heat pump requires a significant amount of land next to the land. Unfortunately, this is not possible for those in big cities, which makes it impossible to utilize geothermal energy without a specialized vertical heat pump.
Is Geothermal Energy Safe For The Environment?
A geothermal plant is overly positive for the environment. One reason for this is that it does not burn fuel to produce electricity. The amount of greenhouse gasses it emits is significantly less than what is emitted by fossil fuel plants. For instance, a geothermal plant emits 97% less acidic rain causing sulfur compounds and 99% less CO2 than a fossil fuel plant of similar capacity.
How Reliable Is Geothermal Energy?
Compared to most other sources of energy, geothermal energy is quite reliable. A geothermal power plant runs 24/7 regardless of weather conditions. This is unlike solar and wind energy, which vary depending on weather conditions.
What Are The Pros And Cons Of Geothermal Energy?
What Are 3 Disadvantages Of Geothermal Energy?
The three main disadvantages of geothermal energy are:
It is Location Specific
A geothermal plant can only be built in an area of active geological activity. Several other factors have to be considered before building a geothermal plant. As a result, geothermal plants are limited to a few locations around the world at current levels of technology.
High Initial Cost
Extracting geothermal energy resources comes with a significantly higher investment compared to other sources of energy. As a result, geothermal power often costs slightly more than other sources of power.
Risk of Triggering Earthquakes
During the drilling and exploration process, there is a risk of triggering earthquakes as well as being dug into geologically active formations.
What Is The Biggest Problem With Geothermal Energy?
The biggest disadvantage of geothermal energy is that it is location-specific. As a result, plants can only be built close to the locations where geothermal energy is being extracted.
These locations are often remote, and far away from population centers. The result is that the initial cost of geothermal energy is driven higher since the transmission network has to be built over long distances.
Why Is Geothermal Energy Not Available Everywhere?
Geothermal energy is not available everywhere. The reason for this is that most of the earth’s surface is geologically dormant except for a few regions where magma flows close to the ground.
Can Geothermal Be Overused?
Geothermal energy is only sustainable under proper management. To make it sustainable, water extracted from the reservoirs has to be pumped back at the same rate to avoid depletion.
Without proper management, these reservoirs could become depleted, rendering a plant non-functional until the reservoirs are filled again.