Where Does Geothermal Energy Come From?
Geothermal energy is heat that comes from Earth’s subsurface. It is contained in rocks and fluids beneath the Earth’s crust and can be found as far away as magma, the hot molten rock of the Earth. To produce electricity from geothermal energy, wells a mile deep are dug in underground reservoirs to access steam and hot water, which can be used to drive turbines connected to power generators. There are three types of geothermal powers plant; Dry Steam, Flash, and Binary.
Dry steam is the oldest form of geothermal technology and extracts steam from the ground and uses it directly to drive turbines. Flash plants use high-pressure hot water to cool, low-pressure water while binary plants pass hot water through other liquids with a lower boiling point, which turns into vapor to drive a turbine.
If you are a renewable energy enthusiast, you may have stumbled across companies creating awareness about geothermal heating and cooling systems & wondered what geothermal energy is & why you should spend some quality time learning more about it.
Must spend Well, today we are going to free you from the hassle of scouring the internet to know what geothermal energy is and its great benefits. The word geothermal is derived from the Greek words; Bhu, meaning Earth, and thermal, meaning heat.
This etymology quickly leads to the definition of geothermal energy, which is the heat released from beneath the Earth’s surface. The energy inside the Earth was created many years ago by the decay of minerals and forests. Traditionally it was used for bathing & heating, but today it is also used to generate electricity.
It is renewable energy sourced, which means it is inexhaustible to humans. It is also green, the source of energy, which means that it does not emit greenhouse gases that are hazardous to human & environmental health.
Types of Geothermal Energy:
This power system is an alternative to a source that uses high electrical energy. The system is efficient, eco-friendly, easy to use, and affordable. It uses about half less energy than other conventional heating or cooling systems.
Although there are many options for these power systems to choose from, environmental requirements and demands must be strictly adhered to. First of all, the types of geothermal power systems are:
#1. Closed Geothermal Loop Systems
Closed Geothermal Loop System is highly energy-efficient, which distributes heat evenly throughout the home by reducing dependence on fossil fuels. Installation cost can be expensive, but it can last 25 years+. Despite this, it absorbs the natural heat from the ground itself and then releases it equally into the particular house.
Systems combine a heat pump that draws water and antifreeze solution through an underground water pipe buried at a shallow depth in your yard. Since it requires little maintenance, it provides heat in a renewable way.
1.1 Horizontal Ground Source of Heat Pump
This requires large space as the two pipes need to be buried parallelly below the horizontal trenches at most 2 m. The advantage of these types of earth loop installation is that more pipes are used per meter in a smaller trench area, making it a more compact design for smaller gardens or plots.
However, the disadvantages are that the heat resource can be easily removed from a very small footprint. This results in less heat evacuation from the ground.
1.2 Vertical Ground Source of Heat Pump
Equally, a vertical ground source of heat pumps is costlier than a horizontal one but can also be installed in a restricted area. And this option does not require large pipes as drilling rigs are required to drill boreholes about 80 meters deep.
The disadvantage of verticals ground source heat pump is that depending on the waters being used from the well, periodic cleaning of the water filter and heat exchanger inside may be necessary.
#2. Open Geothermal Loop System
Open geothermal loop systems work by pumping groundwater from an aquifer or similar to a heat pump. This means that the evaporator transfers its heat. After that, the water is either reintroduced into the ground or released onto the surface.
Thus, the heat sources are similar to the fluid that moves through the circuit and has to be changed constantly because it is not recirculated. The advantage of the system is that it is relatively inexpensive as compared to other systems.
Closed Loop System for Pond/lake
This type is possible where there is a sufficient amount and deep water is present. A pipe has been placed underground from the location to the pond/lake so that the freezing cold does not bother everyone. While it was more expensive to install than an open-loop system, it eliminates the constant intake of well water. As in the case of a closed-loop system, there is no harmful effect on the environment.
Types of Geothermal Power Plants
#1. Dry Steam Power Plants
Source: US Department of Energy, Energy Efficiency & Renewables Energy There are three main types of geothermal powers plant: dry steam plants, flash cycle steam plants, & binary cycle plants. Dry steam plants use naturally produced steam from the ground. The steam to turn the generator turbines comes from the output of the well.
This is possible only in places with the highest temperature. The temperatures vary from 212°F to 608°F. However, it requires less vapor, but the water that is extracted will be in the form of a gas. Italy built the first geothermal power generation plant from a dry steam power plant in 1904. It had a power of 250 kW.
#2. Flash Steam Power Plants
Source: US Department of Energy, Energy Efficiency & Renewable Energy Similarly, flash cycle steam plants do not use steam directly from Earths to generate electricity. Rather it pumps hot waters under high pressure under the Earth.
This is done through wells into the flush tank, which is kept at low pressure. Due to the low pressure of the flash tank, the hot pressure turns into steam. The steam would then spin the turbines and generate electricity.
The water here should be over 356°F. It is a widely practiced type of plant in the present context. Finally, the cooling waters are returned to the underground water tank to be re-heated by the geothermal rocks.
#3. Binary Cycle Power Plants
Source: US Department of Energy, Energy Efficiency & Renewable Energy The last is the Binary Cycle Plant, which transfers heat from geothermal hot waters. It can be considered as the commonly used energy in the future.
Also, it works at low temperatures (224.6°F to 359.6°F), but the other two types cannot. Instead of using water and steam directly, binary cycle plants use heat from underground reservoirs to heat other vapors with lower boiling points. Then it spins a turbine & generates electricity. Its thermal efficiency is 10-13%.
Advantage of Geothermal Energy
The Advantage of using this energy is as follows:
Unlike solar and wind power, this energy does not fluctuate. Energies are always available, so there is no need to depend on other factors to generate electricity. So the calculation process is simple, making it easy to predict the energy result.
#2. Environmental Friendly
Although this energy is withdrawn from under the Earth, there is no emission to the fields. The carbon footprint of the geothermal power plants is minimal, which releases 99% fewer carbons dioxides for every megawatt-hour of electricity it generates.
There may be other factors causing pollution, but this appears to be less in comparison to the production of other resources. For example, free hot water and electricity generation does not cause noise pollution.
#3. Massive Potential Holder
According to data from Learn Mechanical, power plants deliver 12.7 GW of electricity while every other resource delivers 17 terawatts worldwide. In Insomuch, it is estimated that the capacity of geothermal power plants is 0.035 to 2 TW.
After that, geothermal heat pumps systems use 25% to 50% less electricity than conventional systems for heating or cooling; the types require less space and are inexpensive. They are considering that this energy generation has immense potential.
#4. Great for Heating and Cooling
Energy plays an important role in heating and cooling. Icelanders have been using this feature for a long time. This does not require high temperatures, but the steam between the surface and only 2 meters of the well may suffice. This will help heat and cool the building or homes, increasing the homeowner’s savings.
#5. Renewable and Sustainable
It is a natural resource that will be accessible until the planet is wiped out. Plus, it’s free compared to other resources. According to the scientist, geothermal reservoirs is expected to last for billions of years. Fossil fuels have an expiration date, but geothermal energy has no expiration date. This makes electricity both renewable and sustainable.
#6. Rapid Evolution
This era has ushered in unexpected techniques to improve every dimension of each field. Similarly, techniques have been created to exploit natural resources. This shows that there is an increasing trend of development in this area. Therefore, Indonesia and the Philippines are building huge power plants on a large scale for a better future.
Disadvantages of Geothermal Energy:
Nevertheless, each part of the universe has both pros and cons. Similarly, this energy is a certain eco-friendly resource, but some aspects harm our surroundings. To know more about the disadvantages, the following points are well explained.
#1. Environmental Issues
According to the Union of Concerned Scientists, there are a lot of greenhouse gases under the Earth. Whenever this energy is used, some greenhouse gases are released towards the ground and into the atmosphere. In addition, emissions are higher compared to geothermal power plants.
This is because power plants generate small amounts of sulfur dioxide and silica emissions. Sometimes toxic heavy metals, including mercury, arsenic, and boron, are detected in the reservoir.
The pollution associated with geothermal energy is very low and is a tiny fraction of what we see with coal power and fossil fuels. In addition, there’s have been no reported cases of water contamination from geothermal sites in the US.
#2. Higher Initial Cost
Although the energy provides free heat generation, the initial capital cost is high. This is because the cost of drilling wells for an underground water body is expensive. In addition, it is necessary to install heating and cooling systems, which are more expensive than drilling wells.
The reason being expensive is because of the progress in the installation of technologies. For example, a typical heating pump installation can cost around $10,000-$20,000. The return on investment is certainly predictable, but it will take a long time.
#3. Preferable in Certain Areas
This energy is especially extremely hot below the surface areas. However, the hot rock should be suitable enough for digging wells. Not every type of rock helps to dig a well, while the hot bearing capacity varies from one to the other.
Usually, such places are located away from the city where the population is less. Or it can be seen that the places with the highest number of volcanic eruptions are suitable for the huge production of energy. People generally ignore the natural disasters that occur at places. Thus, overproduction can cause damaging environmental issues as the need is in a populated place.
#4. Cause Surface Instability
When a surface is drilled, the surface is likely to become unstable and cause earthquakes. Constructions of a conventional geothermal power plant require the drilling of hot rock. They contain water or steam trapped in their starting places and natural eruptions.
When these partitions are split by a drilled hole, the trapped water explodes as steam. The drilling itself may not trigger an earthquake, but steam rupture and later return the used water to a hot water reservoir. The cycle leads to uncertainty along the burst lines, which can result in earthquakes.
#5. Experience Dry Spell
The geothermal heat coming from the reservoir below can die off or run out of steam after years of use. The lack of every aspect required by the land can last for decades, which is why it is recommended to use heat judiciously and not to abuse it. Inconsistent use can also result in a poor distribution of heat.
Practices of this energy have existed for centuries, growing rapidly over the past three decades for both the generation of electricity and the direct use of heat. Initially, the efficiency of a geothermal system is only 20%, but this is common in power generation facilities.
The environmental impacts of energy facilities are less than that of any other natural resource. It produces electricity on a large scale with 99% less carbon dioxide with no emissions. For example, wells at least a mile or more deep are drilled in underground reservoirs to connect to geothermal resources.
These resources can be exploited forms naturally occurring heat, rock, & water or through advanced geothermal systems, which augment or create geothermal resources through hydraulic stimulation. These geothermal resources, whether natural or advanced, drive turbines connected to power generators and generate heat.
In winter, geothermal heating pumps systems can elevate the temperature of the upper 3 m of Earth’s landmass. It occurs when heat is removed from homes in summer and transferred to the cooler ground. Geothermal water from the depths of the Earths can be used directly to heat homes and offices or to grow plants in greenhouses.
Some US cities typically place geothermal hot water energy pipes under streets and sidewalks to melt snow. Increasingly, this energy is considered very practical from an economic point of view. It is considered a cheap, never-ending resource & base-load generator.
However, setting up a geothermal power plant is not cheap. It requires advanced technologies & human resources before a huge return on investment. Well, the first country to harness the possibilities of geothermal energy was Italy in 1904.
Similarly, it is believed that monkeys from Japan used this method from hot springs. The purpose was to keep me warm in winter. Today, the United States owns the world’s largest geothermal development, located at Geyser north of San Francisco, California.