Renewable Energy Resources and Technologies
Mirmahdi Seyedrahimi-Niaraq; Tohid Nouri
Abstract
Geothermal energy is a non-carbon renewable source from the earth's internal energy. This energy is considered reliable today and has a high potential to reduce the threat of climate change. The main factor that any investor wants to invest in any natural energy source is the resulting economy. In the ...
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Geothermal energy is a non-carbon renewable source from the earth's internal energy. This energy is considered reliable today and has a high potential to reduce the threat of climate change. The main factor that any investor wants to invest in any natural energy source is the resulting economy. In the case of geothermal energy, factors that increase the risk of investing in this sector include higher investment costs, longer payback times than other renewable power plants, and the uncertainty of the size and quality of the resources before the completion of the well drilling operation. The average payback time in geothermal energy systems is 5.7 years, longer than wind and solar energy. According to these factors, the risk of investing in geothermal technology increases. On the other hand, due to its independence from oil and gas, it increases a country's energy security, helps to create direct, indirect, and induced employment, and affects other economic sectors. Also, unlike renewable wind and solar energies, it is not dependent on climate change; therefore, it has higher reliability than other renewable energies. Also, by combining this energy with other renewable energies, its performance can be optimized. For example, in an optimal geothermal-solar hybrid power plant, solar energy provides 48 % of the total energy. In this case, the Levelized Cost of Energy (LCOE) is reduced from 225 $ per MWh (only with geothermal source) to 165 $ per MWh. In this study, while studying the economic effects of geothermal systems, an attempt has been made to address the challenges in this field and present the policies implemented in some countries. It is implied that by providing incentive policies and an appropriate roadmap, it is possible to help attract investment in the operation of geothermal systems.
Renewable Energy Resources and Technologies
Reza Roohi; Alireza Bahramian; Sepideh Samghani
Abstract
Ground thermal energy as a clean and sustainable energy source has received significant attention lately. Several strategies and hybrid configurations have been proposed to harvest geothermal energy for air conditioning and industrial purposes. The possibility of moist soil freezing in the vicinity of ...
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Ground thermal energy as a clean and sustainable energy source has received significant attention lately. Several strategies and hybrid configurations have been proposed to harvest geothermal energy for air conditioning and industrial purposes. The possibility of moist soil freezing in the vicinity of borehole tubes is known to be the source of several benefits and difficulties. The high storage capacity during the freezing process and the structural damage are the major advantages and disadvantages of the thawing phenomenon, respectively. In the present study, the numerical simulation of the freezing process around the U-tube configuration of boreholes accompanied by the solar energy injection as the auxiliary heat source is investigated. Lower values of cold stream temperature result in the higher amount of recovered heat, while increasing the injected heat temperature intensifies the heat regaining. Moreover, the energy absorbed by the ice layer around the tube is directly related to the cold stream temperature.
