Concepts of geothermal power generation system

Discuss about the Geothermal Power for Sustainable Thermal System.

Bayer et al., (2013) stated that geothermal power is the power, which is produced by the geothermal energy. The technologies utilized for the geothermal power are dry stream power stations, binary cycle power stations as well as flash stream power stations. As of 2015, the capacity of the geothermal power is of amounts to 12.8 gigawatts (GW). This power is considered as sustainable renewable sources of energy as the removal of heat is small as evaluated with Earth’s heat content. Bertani (2012) argued that the interior of the earth is predictable to carry on very hot for billions of years, makes sure for limitless heat flow. Geothermal power plants are capturing heat as well as converting it into energy in electricity type. The below image demonstrates the basis of production of geothermal electric power and warm from the Earth. As there is a raise in a depth of Earth, the temperature also increases. 

Figure 1: Temperatures in the Earth

(Source: Bayer et al., 2013, pp-451)

Zarrouk and Moon (2014) discussed on the basic principles of this geothermal power are that heat will stream from the region, which is hotter than the region, which is cooler, but on no account the other way about. The earth captures the heat from the ray of the sun as well as stores it below the ground. With a couple of pipes, heat exchanger as well as a distribution system, it is easy to utilize the geothermal energy in most of the household’s appliances.

The low-temperature thresholds for generation of power are changing to advanced power generation technologies using fluids that heat at low temperature than water. Where the temperatures are inadequate to produce stream directly, a binary system approach is being used. Coskun, Bolatturk and Kanoglu (2014) reflected that in the non-volcanic regions, generations of power from geothermal resources are centred on the binary systems at lesser heat or expansion of Enhanced Geothermal System technologies (EGS) at the high temperature. According to Chamorro et al., (2012), currently the most widely recognized approach to capturing the energy from the geothermal resources is to tap it into actually happening hydrothermal convention system. Ghasemi et al., (2013) argued that in the particular system, the cooler water saturates the crust of the Earth, and afterward it is warmed up as well as rises to the surface. Once the warmed water is compelled to the surface, it is simple to capture the stream as well as after that utilization it to make electric generators. Geothermal power plants are utilized to drill holes into the stone in order to capture stream.

Technologies used in geothermal power generation

Advantages and disadvantages of available geothermal power technology

Developed in the 1980s, the technology is being developed in the use of geothermal power plants through the globe in areas that consisted of lower resource temperatures (Stachel & Wisniewski, 2015). The capability in order to utilize of lower temperature resources raises the number of the reservoirs that are used for a production of power. Bouncier et al., (2015) stated that there are three basic designs for the geothermal power plants, which are categorized as follows:

Geothermal flash power plant: It generates power by using geothermal reservoirs of water that consist of temperature greater than 360 degrees Fahrenheit. Karlsdottir et al., (2015) opined that within this power plant, high-pressure separates stream from the water within stream separator when the pressure is dropped, and water is raised. The stream is delivered into a turbine and then it powers a generator. Any leftover water, as well as stream, are injected back to the reservoir and make it a sustainable resource (DiPippo, 2012). It is the most popular method to generate geothermal power.

Figure 2: Geothermal flash power plant

(Source: Karlsdottir et al., 2015, pp-507)

Geothermal dry stream power plant: Buonocore et al., (2015) stated that it generates power by drawing stream from the underground resources. The stream is produced straightforwardly from the geothermal reservoir, and it is used to run the turbines, which control the generator. As there is no water, therefore the stream separator utilized in the flash is not required (Bertani, 2016). This power plant accounts for 50 percent installed geothermal capacity in Australia. The example for an underground resource for the stream is geysers.

Figure 3: Geothermal dry stream power plant

(Source: Buonocore et al., 2015, pp-479)

Geothermal binary power plant: It generates power using water at a temperature of 225-360 degree Fahrenheit. Astolfi et al., (2014) opined that this power plant uses of geothermal water to heat up second liquid that simmers at low temperature. The exchange of heat divides the water from the working fluid while moving the heat energy. When the functioning fluid is vaporized, then the force of increasing vapor such as steam turns the turbine, which powers up the generator (Odum & Zarrouk, 2015). After that, the geothermal water is re-injected into a congested loop and then it separates from a basis of groundwater with lowering the rate of emissions.

Figure 4: Geothermal binary power plant

(Source: Astolfi et al., 2014, pp-437)

From the three used technologies for geothermal power generation, it is identified that the technological use of geothermal energy is electrical supply of power, sustainable power generation modes, power plants as well as heating and cooling. Pambudi et al., (2014) discussed that geothermal plants are very low planned as well as unplanned outage rates. The availability of the geothermal power is measured as some hours that a power plant is being accessible. It is kept in mind that the end goal is to deliver power partition by aggregate hours in a set of a time period, for the most part, a year of around 95 percent (Luo et al., 2014). It is then recognized that the geothermal power plants are accessible for an era of 95 percent of the time, taking into account the perceptions of the plant administrators.

Advantages of geothermal power technologies

The following are advantages of geothermal power, which creates a protected environment, and it is exceptional sources of low-priced, easy, renewable as well as consistent power.

Cost saving: Li et al., (2015) stated that the geothermal power is one of the renewable sources of energy. Due to a use of the current technologies, geothermal power engages low running cost, and it keeps 80 percent costs over the fossil fuels. No fuel is utilized for creation of power, and it does not need purchasing as well as transporting costs.

No pollution: It is non-polluting, zero carbon as well as environmentally friendly. Guan, Hooman and Gurgenci (2016) discussed that due to renewable sources of energy, the power helps to reduce global warming as well as pollution. There is no consumption as well as a generation of by-products. It is not needy on the weather circumstances.

Direct use of geothermal power: It is used directly. It is used for some of the purposes such as heating homes, cooking purposes. Alimonti and Soldo (2016) reflected on the statement that as it is directly used, therefore it is both cheaper as well as affordable. The initial investment is vertical but in the end with a huge saving of cost makes it functional.

Less space and maintenance: Maintenance of the geothermal power plant is less. Geothermal heat pump systems are using 25 percent to 50 percent less electricity as conventional systems to heat or cool (Csanyi et al., 2010). It also requires a flexible design with less space for hardware is required. As geothermal power plants are not occupying much space, therefore it is used to protect the natural environment.

Latest technological use: Due to technological advancement such as enhanced geothermal systems, it makes to have more resources exploitable as well as lowers the cost.

Location site issues: Only a few of the sites have the probable of geothermal energy. Most of the sites where the geothermal energy is being formed are distant from the cities. Therefore it requires consuming (Astolfi et al., 2014). Sometimes, it is lost due to long distance transmission of electricity.

High installation cost: Installation of a cost of steam power plant is high. Guan, Hooman and Gurgenci (2016) opined that the installation of geothermal power system requires a certain amount of land for the system to be installed. Therefore, it makes impossible to implement geothermal systems for house owners within big cities. Csanyi et al., (2010) argued that there are no such guarantees that the quantity of energy that is formed will authenticate the capital spending as well as operational cost.

Environmental issues: Sometimes, it releases harmful as well as poisonous gasses that escape through holes drilled during the construction (Ghasemi et al., 2013). The power plants are related to sulfur dioxide, silica emissions, as well as reservoirs, consists of toxic heavy metals. 

Sustainability issues: Odum and Zarrouk (2015) stated that reservoirs are exhausted if the liquid is being expelled speedier replaced. Efforts are given to infuse the liquid once again into the geothermal reservoir after the thermal energy is being used. The geothermal power is considered as sustainable if the reservoirs are aimed at efficiently.

Stachel and Wisniewski (2015) opined that the bottom line is that geothermal power is regarded as environmentally friendly, reliable as well as sustainable. It makes the energy no-barrier but due to heavy installation cost, it may become a barrier sometimes.

Geothermal power has some of the barriers which are required to overcome such as high temperature are concentrated in particular areas; it has lower capacity factor and site location issues. Coskun, Bolatturk and Kanoglu (2014) stated that due to those identified barriers, it gives negative impacts on the research and environment. The negative impacts are related to hot water as well as gasses released into the environment. Technological barriers lie in high exploitation, a high cost of investment for production of electricity as well as a risk of failure during exploitation. Ghasemi et al., (2013) argued that sometimes, regulation, as well as administrative procedures, is the obstacles that do not encourage application as well as diffusion of renewable energy. The main problems that are required to overcome are an improvement in resource assessment as well as forecasting, improvement in drilling technologies, system integration, and environmental impact mitigation.

Bertani (2016) opined that further research is undertaken, technology advances are made as well as literature becomes available in the findings of the study might require reviewing as well as re-evaluate. In the research, where the gaps of the information are identified, they are noted, and recommendations are made for future study. Pambudi et al., (2014) argued that the problem with the generation of power is wastage of heat, which is excess stream are produced when transforming the geothermal energy to power. One of the solutions for this problem is environmental legislature assign restraints with an addition of cooling ponds near the extraction site. Li et al., (2015) reflected that the geothermal energy focuses on the current status of research on energy regards of different technologies.

Geothermal power has played a potential part in moving Australia toward a more sustainable energy system. It is considered as one of the renewable energy advancements that provide consistent and additionally base load powers. Alimonti and Soldo (2016) opined that among three power plants, binary geothermal plants are utilized as an adaptable source of energy keeping in mind the end goal to adjust the variable supply of renewable resources. This kind of plant has the ability to incline generation up and also down different times every day, from 100 percent of nominal power down to least of 10 percent (DiPippo, 2012). In the future, in order to use of geothermal power, two of the emerging technologies need further development such as:

Enhanced geothermal systems: Geothermal heat happens under the surface of the earth and the way to capture the heat within the dry areas is defined as enhanced geothermal systems. Csanyi et al., (2010) stated that this technology consists of challenges such as securing well commercial productivity, minimize cooling as well as water loss are required to overcome before it is viable. As this system offers a promise of worldwide distribution, therefore it is most potential for future use.

Co-production of geothermal power within oil as well as gas wells: The lower temperature of geothermal energy is being resulting from a geothermal liquid that is originate at temperatures of 150 degrees. Buonocore et al., (2015) expressed that the geothermal resources are used for direct utilize applications, for example, warming of a building. In any case, it produces power through double cycle procedures of geothermal. Oil and gas segments are on the item, which represents to a huge capability of sources of this kind of geothermal energy. Coskun, Bolatturk and Kanoglu (2014) argued that in existing oil and in gas reservoirs, a huge measure of higher-temperature water is available that takes into consideration co-generation of geothermal power alongside the removal of oil as well as gas resources (Huddlestone-Holmes, 2014). In some of the cases, the misuse of the geothermal resources upgrades the oil and gas extraction.

Convective or hydrothermal systems: The hydrothermal resources are raised when hot water is created in fractured rock at low to modest depths as an outcome of intrusion within the earth’s crust (Bertani, 2012). Hot molten rocks heat high temperature of hydrothermal resources. More than 9000 MW of the power is being generated from the conventional geothermal reservoirs. Zarrouk and Moon (2014) stated that the countries should have a possibility to produce 10,000 to 30,000 MW, excluding the hydrothermal systems are commercially demoralized for decades. Even its growth hampers by limited distribution worldwide.

Conclusion 

It is concluded that the geothermal power minimizes the air pollution such as the new state of ability geothermal binary cycle plants are produced no air emissions. It is also seen that all the geothermal energy are the renewable sources of energy as the rate of extraction of heat from the earth does not exceed the rate at which the thermal reservoir it depends on upon is revitalized by the earth’s heat. It is recommended that improvement over enhanced geothermal system technologies is one of the prospects which become competitive, even untapped geothermal resources are developed. The paper reflects that the most common method to capture the energy from the geothermal sources is to tap into the hydrothermal system wherever the cooler water is heated up as well as rises to the surface. Some of the technological barriers lie in this research is high exploitation, a high cost of investment for production of electricity as well as a risk of failure during exploitation.

References

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