What is Geothermal Energy?
Geothermal energy is heat derived within the sub-surface of the earth. Water and/or steam carry the geothermal energy to the Earth’s surface. Depending on its characteristics, geothermal energy can be used for heating and cooling purposes or be harnessed to generate clean electricity.
The word ‘geothermal’ literally means ‘earth’ and ‘heat’ – heat energy from the earth. There are many advantages to using it as an energy source. It is safe, renewable, a source of heat and electricity, and emits much fewer greenhouse gases than solar panels.
However, for electricity, generation high or medium temperature resources are needed, which are usually located close to tectonically active regions.
The Earth’s surface absorbs about 45% of the sun’s radiation that reaches it and reflects the rest back. The remainder is partially absorbed by the atmosphere and partially reflected back into space. Temperatures at a depth of 6–10 m are maintained throughout the year at 10–16 C and uniformly on Earth.
Little change is dependent on the local climatic zone and soil type. The temperature of the Earth is also controlled by magma at its center. It is a resource that is regular and long-lasting.
History of Geothermal System
About 10,000 years ago the first settlers chose to settle near the hot springs. The ancient Romans used water for bathing, cooking, and medicinal purposes. They also used water to heat their homes.
Geothermal energy was first used in 1830 at Hot Springs Arkansas by alias Thompson when he charged $ 1 for Hot Spring Bath. During the late 1800s, hotels and spas came up around Geiger in San Francisco California. In 1892, 200 homes and 40 businesses in Boise Idaho were provided with the first district heating system that is functioning to date.
The Larder Aloe farms in Italy were owned by Prince Piero Conti, who mounted a generator in a naturally operated steam engine and produced electricity to light 4 bulbs. By 1911 and then the world’s first geothermal plant was set up which provided 250 kW. It still generates 405 MW of power generation.
The Geiger Resort Hotel in California was the location of the first geothermal plant in the US, in 1922, by John D. Was built by Grant and it generated electricity for the entire resort. In 1960, Pacific Gas & Electricity began operating the first successful power plant at The Geysers and today has 21 geothermal power plants in the region currently owned by the Calpin Corporation and Northern California Electricity Agency.
Until the 1950s water source heat pumps were designed for residential purposes and by the 1980s they were improved by geothermal heat pumps and the technology is still evolving today. Today, geothermal energy is produced in more than 20 countries.
In 2008 it was estimated that 1% of geothermal energy produces energy. By 2050 it is projected to grow to provide at least 10–20% of world energy.
Geothermal Power Plant
Geothermal power plants use hydrothermal resources that have both water (hydro) and heat (thermal). Geothermal power plants require high-temperature (300°F to 700°F) hydrothermal resources that come from either dry steam wells or from hot water wells. The hot water or steam powers a turbine that generates electricity.
Several miles below the Earth’s surface there is a deposition of groundwater that is naturally heated by the Earth’s magma. This water is drawn through shafts or wells by natural pressure. As soon as it reaches a low pressure.
It turns into steam which is then used to turn on the turbine connected to the generator. And its heat energy is transferred and stored as electrical energy.
Types of Geothermal Power Plant
There are three types of geothermal power plants: dry steam, flash steam, and binary cycle. Dry steam power plants draw from underground resources of steam. The steam is piped directly from underground wells to the power plant, where it is directed into a turbine/ generator unit.
There are three types of geothermal power plants:
- Dry steam
- Flash steam
- Binary cycle
These were the first types of geothermal power generation plants. They were made in Larder Aloe, Italy, and Geyser, Northern California. The proponent used here is steam. Excess steam is delivered with very minor amounts of other gases. No fossil fuels are used to drive the turbine.
When hydrothermal fluids are available at temperatures higher than 182C (360F), flash systems are used to turn the turbine. At high pressure, the liquid is sprayed into a low-pressure tank and evaporates immediately. This steam is applied to power the turbine forcing the generator. The remaining liquid can flow to another tank from which more energy is extracted.
Geothermal liquid found in many places is less than 210C and is used in conjunction with another liquid or “binary”. That has a lower boiling point than geothermal liquid. The two fluids do not come into contact. But the heat is transferred to the binary liquid, it is vaporized and used to power the turbine. It is now the more common type of geothermal plant to be built.
Direct Use Geothermal Hot Water systems
It is a technique using hot water close to the surface of the earth to directly heat buildings, roads, and sidewalks found near reservoirs, with temperatures up to 20–150C. These methods are primarily found in the western United States.
Very little external energy is used and the percentage of pollutants released is also very low. Greenhouses and food processing units also benefit from this system. Hot water is also supplied directly to the communities.
Shallow Ground Energy System
The ground temperature is maintained at a constant 10–16C of the year at a depth of 4–6 m. It is kept at this depth, taking advantage of several meters of high-density polyethylene pipe called Advantage Loop ‘. Its size depends on the building type of loop installed terrain, soil type, and the heating and cooling load required by the local climate.
The fluid is circulated in a loop and sent to geothermal heat pumps. When heat is required the liquid absorbs the earth’s heat and when the cooling effect is desired the excess heat of the building is released into the earth. The air-conditioned air is then guided by heat pumps into the building.
A complementary advantage of this system is that hot water can also be supplied to the building using the same loop. During heat exchange, excess heat from the building is transferred to its hot water system before reaching the ground loop. No additional energy is required to heat the water nor do the gases emit because everything is in a closed-loop. This makes the entire system more efficient.
Uses of Geothermal Energy
Geothermal energy, form of energy conversion in which heat energy from within Earth is captured and harnessed for cooking, bathing, space heating, electrical power generation, and other uses.
- Production of electricity
- Heating requirements of buildings and districts
- Hot water supply
- Heating the paths and roads to melt snow.
- Heating for greenhouses to grow vegetables, flowers, seedings, etc.
- Running aquaculture operations to raise fish, shrimp, tropical fish, and other species.
- Dehydration of food items like onion and garlic
- Industrial uses- laundries, drying grains, mushroom cultivation
- Waste management-Sludge digestion is a biological process using heat and microbes to convert organic solids into stable and dry substances
- Resorts and spas in the tourism industry.
Effect of Geothermal Energy
There are benefits and drawbacks associated with geothermal energy. Its benefits are that it is clean, renewable, and easily available. Most of the damage lies in its discovery and plant construction phases.
As more research is done and there are developments in processing and pollution control technology. These should be implemented in existing geothermal plants. Although the benefits of doing so are great, the financial cost is significantly higher. Incentives and tax cuts will encourage companies to add such value to their product.
- Water vapor is the main component in plants arising from geothermal plants.
- Hydrogen sulfide H2S is released using geothermal energy. Its emissions are reduced or eliminated in plants. 99.9 percent of H2S is now converted to elemental sulfur, which is then used as soil and fertilizer feedstock.
Where there is no remedy to control H2S emissions. It results in foul smells and causes pollution for the local people.
- Toxic factors such as radon, mercury, arsenic, ammonia, and boron emissions are also observed. These can be eliminated by more than 90% in plants. Not all geothermal sources contain mercury. Geyser facilities in California are assessed under strict California regulations and the mercury levels released here are not considered harmful to human health.
- Emissions of greenhouse gases are almost negligible compared to coal and natural gas plants.
2) Noise pollution
The level of noise generated during the production level is generally said to below.
Disadvantages: but there is too much noise drilling in the exploration phase, which can exceed the pain threshold of 120 decibels. During production, it comes to 90 dB which is still heard at some distance. This can cause disturbances in tourist spots and local entertainment.
Water use and quality
- Water is the main carrier for the heat energy used in the plant.
- Water drawn from the resource is normally injected back into the geothermal reservoir. They are not released in surface water systems. This helps to maintain the stability of the reservoir. Thick cover wells prevent contamination of local groundwater systems.
Disadvantages – Where geothermal plants are particularly old where the injection technique has not been implemented or upgraded, where residual water is released to the surface and causes groundwater contamination.
When steam of wastewater is sprayed onto surrounding vegetation or heavy metal-laden wastewater or hot water is released into streams and lakes, they have devastating ecological effects on susceptible species in natural habitat.
3) Land effect
- Geothermal plants can be located on multiple-use lands such as farming, skiing, aquaculture operations, or hunting facilities
Disadvantages Subsidiary: Submerging downstream of the land can be associated with hydrothermal reservoir pressure degradation. Injection technology (restoration of water used back into the reservoir via wells) minimizes the occurrence of subsidence.
Induced seismicity: low-magnitude events called micro-earthquakes are seen as a result of geothermal production and injection operations. They cannot be detected by humans, but they are voluntarily monitored at facilities.
Landslide: Due to the loosening of surface soil
4) Protected area
Many geothermal resources do not have significant surface features and are only discovered by exploration. But sometimes there are signs of large geothermal resources such as natural surfaces such as geysers (hot springs, where hot water steam and gas burst from time to time), fumaroles (vents for gas and steam).
It is feared that these surface features will be used for geothermal development. But scientific studies suggest that they cannot be a sustainable source of energy and are therefore usually not abandoned. Such areas may fall into protected areas, for example. Yellowstone National Park is ‘Old Faithful’ with the famous Geiger.
Active sites for geothermal sources are found in areas of high natural value (hot springs, volcanoes, glaciers). The construction of power plants here disturbs the natural landscape with the presence of roads, power lines, factories, trucks, and drilling equipment. This causes disturbance of the forest surface.
The capacity of geothermal energy is very large and can be used globally. As the world’s energy needs increase along with the threat of global warming, geothermal energy is now being used as an alternative to burning fossil fuels. The cost of building plants is still high, but with advances in technology and processes, it can be brought to affordable levels.
There must be continuous development of technologies, which ensure that the impact of exploration and production does not harm the surroundings. Implementation of these technologies, despite the cost of doing so, can keep this resource strong and help reduce our dependence on other pollution-causing resources. It does not require the transportation of raw materials or management resources. It is a major alternative to alternative energy.
How is geothermal energy generated?
Geothermal power plants use steam to produce electricity. The steam comes from reservoirs of hot water found a few miles or more below the earth’s surface. The steam rotates a turbine that activates a generator, which produces electricity.
What is bad about geothermal energy?
Potential emissions: Greenhouse gas below Earth’s surface can potentially migrate to the surface and into the atmosphere. Surface Instability Construction of geothermal power plants can affect the stability of land.
How reliable is geothermal energy?
Geothermal energy is physically reliable because it is consistent, efficient, and can easily accommodate changes in electricity demand.
What is good about geothermal?
First, it’s clean. Energy can be extracted without burning a fossil fuel such as coal, gas, or oil. Geothermal fields produce only about one-sixth of the carbon dioxide that a relatively clean natural-gas-fueled power plant produces, and very little if any, of the nitrous oxide or sulfur-bearing gases.
Why is geothermal energy costly?
Most of the costs related to geothermal power plants are related to resource exploration and plant construction. Like oil and gas exploration, it is expensive and because only one in five wells yield a reservoir suitable for development.