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[en] Development and diffusion of new renewable energy technologies play a central role in mitigating climate change. In this context, small-scale deep geothermal power has seen growing interest in recent years as an environmentally friendly, non-intermittent energy source with large technical potential. Following the first successful demonstration projects, the German geothermal industry is currently experiencing an internationally unparalleled growth. In this study we explore the factors driving this development, and the role geothermal power production could play in the future of the German electricity market. For this, we apply the scenario technique, based on literature analysis and interviews with companies operating actively in the field. Our findings highlight the importance of political support and framework conditions in the electricity market, with the best prospects in a decentralised energy system based on renewable energy sources, where high investment costs and the risk of discovery failure are balanced by the benefits of low-carbon base load power. (author)
[en] Bulgarian territory is rich in thermal water of temperature in the range of 20 - 100oC. The highest water temperature (98oC) is measured in Sapareva banya geothermal reservoir. Electricity generation from geothermal water is not currently available in the country. The major direct thermal water use nowadays covers: balneology, space heating and air-conditioning, domestic hot water supply, greenhouses, swimming pools, bottling of potable water and geothermal ground source heat pumps (GSHP). The total installed capacity amounts to about 77.67 MW (excl. GSHP) and the produced energy is 1083.89 TJ/year. Two applications - balneology and geothermal ground source heat pumps show more stable development during the period of 2005 - 2010. The update information on the state-owned hydrothermal fields is based on issued permits and concessions by the state.
[en] Geothermal gas sampling has been done in the hot springs using a stainless steel funnel which has been modified by Giggenbach method. Modified funnel performed in order to conduct sampling at the site of hot springs that has a wide diameter, so that the gas bubbles coming out of the spring base can be accumulated in the sample bottle. Furthermore, the gas was analyzed by using two methods, for soluble gas (condensable gases) such as CO_2 and H_2S were analyzed by titration methods, while the insoluble gas (non-condensable gases) such as He, H_2, N_2, O_2, Ar and CH_4 were analyzed by gas chromatography methods. The results show that the sampling technique using a stainless steel funnel produces gas that can be measured well. (author)
[en] In order to favour the use of small-scale geothermal energy, this decree has simplified the regulatory framework by substituting an on-line work declaration to the previous authorization-based regime. This article analyses and discusses the content of this decree which makes the distinction between small-scale geothermal energy, low temperature geothermal energy, and high temperature geothermal energy. The decree modifies the mining title regime, simplifies procedures of exploitation of small scale geothermal sites. The author outlines that this new regime will be more precisely defined by other decrees which are to be published during the summer 2015, and will be completed by arrangements which are part of the bill on energy transition
[en] Highlights: ► Applying exergy, economic, environment and sustainability analyses to the GDHSs. ► Assessing energy and exergy efficiencies, economic and environmental impacts. ► Calculating the energy and exergy efficiencies of 34.86% and 48.78%, respectively. ► Proposing GDHSs as the most economic heating system. ► Providing a significant contribution towards reducing the emissions of air pollution. - Abstract: This study deals with an energetic and exergetic analysis as well as economic and environmental evaluations of Afyon geothermal district heating system (AGDHS) in Afyon, Turkey. In the analysis, actual system data are used to assess the district heating system performance, energy and exergy efficiencies, specific exergy index, exergetic improvement potential and exergy losses. And, for economic and environmental evaluations, actual data are obtained from the Technical Departments. The energy and exergy flow diagrams are clearly drawn to illustrate how much destructions/losses take place in addition to the inputs and outputs. For system performance analysis and improvement, both energy and exergy efficiencies of the overall AGDHS are determined to be 34.86% and 48.78%, respectively. The efficiency improvements in heat and power systems can help achieving energy security in an environmentally acceptable way by reducing the emissions that might otherwise occur. Present application has shown that in Turkey, geothermal energy is much cheaper than the other energy sources, like fossil fuels, and makes a significant contribution towards reducing the emissions of air pollution.
[en] Geothermal studies, as dictated by the further study of the geological structure of the territory of Belarus, the geodynamics of the Earth's interior, in the light of the continuing rise in prices for imported hydrocarbons; search for alternative renewable clean energy. (authors)
[en] The paper offers a brief overview of the current direct geothermal uses in Greece and discusses their characteristics, with emphasis to the economical and technical problems encountered. Greece holds a prominent place in Europe regarding the existence of promising geothermal resources (both high and low-enthalpy), which can be economically exploited. Currently, no geothermal electricity is produced in Greece. The installed capacity of direct uses at the end of 2009 is estimated at about 155 MWt, exhibiting an increase of more than 100% compared to the figures reported at the World Geothermal Congress 2005. The main uses, in decreasing share, are geothermal heat pumps, swimming and balneology, greenhouse heating and soil warming. Earth-coupled and groundwater (or seawater) heat pumps have shown a drastic expansion during the past 2-3 years, mainly due to high oil prices two years ago and easing of the license requirements for drilling shallow wells. (author)
[en] Highlights: ► The ground can be used as a storage tank to store hot or cooled water in Jordan. ► The stored energy in rocks was utilized to provide heating cooling, and hot water for homes. ► The underground geothermal horizontal loop in rocks was technically approved. ► It can extract up to six times the heat energy that used in electrical energy. ► Its low capital cost and zero environmental emissions. - Abstract: Earth Energy Systems (EESs) utilize the thermal energy that is stored in rocks and ground water under the earth’s surface to provide homes, commercial buildings, and industrial facilities with heating, cooling, and hot water. Solar energy is absorbed by the earth’s surface which stores up to 50% of the sun’s energy that radiates on it. Consequently, the earth and groundwater’s temperature is relatively constant compared to that of the surface air. The earth’s temperature is generally warmer than the surface temperature during the colder months of the year, while it is generally cooler than the surface temperature during the hot months of the year. In this study, energy was extracted from the underground rocks at Mutah University in Jordan by using the geothermal horizontal closed loop system. Two-meter holes were drilled into the earth’s surface; copper pipes were inserted for liquid to pass through them into the heat exchange system. Then, the liquid was circulated back into the ground. Several temperature differences were measured and reported in the cold and hot months. The experimental results showed that thermal energy stored in rocks can be used to provide homes with heating, cooling, and hot water with low capital cost and zero environmental emissions.
[en] Total geothermal energy potential of the Slovak Republic is estimated for 209 714 TJ per year or 6 650 MWth. Natural conditions define a use of thermal waters for heat generation only. Accepting proportion of real achievable output of geothermal projects in the non-conservative scenario at a rate of 1 861 MWth or 13 440 TJ per year, yearly carbon dioxide savings are up to reach 0.357 Mt CO2/yr or 12.5 of cumulative Mt CO2 in 35 years. By a contrast, introduction of conservative approach points to increase in a geothermal heat production from 145 to 243 TJ per period or 6 944 TJ of cumulative 35 years production, with a real outcome of 0.45 Mt CO2 cumulative carbon dioxide savings, corresponding to yearly real savings from 9.4 · 10-3 to 15.8 · 10-3 Mt CO2. (authors)
[en] Highlights: • Geothermal energy is used to preheat the feedwater in a coal-fired power unit. • The performance of a hybrid geothermal–fossil power generation system is analyzed. • Models for both parallel and serial geothermal preheating schemes are presented. • Effects of geothermal source temperatures, distances and heat losses are analyzed. • Power increase of the hybrid system over an ORC and tipping distance are discussed. - Abstract: Low-enthalpy geothermal heat can be efficiently utilized for feedwater preheating in coal-fired power plants by replacing some of the high-grade steam that can then be used to generate more power. This study analyzes a hybrid geothermal–fossil power generation system including a supercritical 1000 MW power unit and a geothermal feedwater preheating system. This study models for parallel and serial geothermal preheating schemes and analyzes the thermodynamic performance of the hybrid geothermal–fossil power generation system for various geothermal resource temperatures. The models are used to analyze the effects of the temperature matching between the geothermal water and the feedwater, the heat losses and pumping power during the geothermal water transport and the resource distance and temperature on the power increase to improve the power generation. The serial geothermal preheating (SGP) scheme generally generates more additional power than the parallel geothermal preheating (PGP) scheme for geothermal resource temperatures of 100–130 °C, but the SGP scheme generates slightly less additional power than the PGP scheme when the feedwater is preheated to as high a temperature as possible before entering the deaerator for geothermal resource temperatures higher than 140 °C. The additional power decreases as the geothermal source distance increases since the pipeline pumping power increases and the geothermal water temperature decreases due to heat losses. More than 50% of the power decrease is due to geothermal water temperature decreases along the pipeline since less higher pressure extracted steam is replaced by the geothermal water. For geothermal resource temperatures of 140–160 °C, the additional power generated by the hybrid geothermal–coal power generation system is about 90% (at a geothermal source distance of 0 km) or 39–49% (at a distance of 20 km) greater than the power generated by an optimized organic Rankine cycle system using isopentane (R601a), the hybrid power generation system has little benefit over the ORC system when the distance increases to 40 km. However, the additional power generated by the hybrid power generation system is less than the power generated by the ORC system at distances over 20 km for geothermal resource temperatures of 100 °C.