Energetic Use of EGS Reservoirs

Handling of the geothermal fluid, which is typically a complex mixture of salt solution and dissolved gases, is one of the main challenges for designing and operating reliable and efficient geothermal power plants. In the geothermal fluid loop, undesired mineral precipitation and fluid-material interactions must be prevented and the design and dimensioning of all components must be adapted according to the characteristics of the geothermal fluid. This paper outlines geochemical and process engineering aspects as well as research activities in these fields and introduces the Groß Schönebeck site, which is a central site for geothermal research.

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“…Further general information on fluid components and their effect in geothermal plants is addressed by Saadat et al [5].…”

Section: +mentioning

confidence: 99%

“…In the binary unit, a working fluid with low boiling point is circulated, mostly because the direct use of the geothermal fluid in the conversion cycle is not as efficient from a thermodynamic point of view, e.g. [5,6].…”

Section: Introductionmentioning

confidence: 99%

Geochemical and Process Engineering Challenges for Geothermal Power Generation

Frick

Regenspurg

Kranz

et al. 2011

Chemie Ingenieur Technik

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“…In order to efficiently use a wider temperature domain, different applications demanding successively lower temperatures are ideally implemented in a cascade (International Energy Agency 2011;Líndal 1973). Space cooling is also possible using geothermal heat with a minimum temperature of 60°C to 70°C as an energy source for heat-driven sorption chillers instead of electrically driven compression chillers (International Energy Agency 2011;Líndal 1973;Saadat et al 2010). Another important field of application related to geothermal energy is the seasonal storage of solar energy or spare heat in deep aquifers (e.g., Stober and Bucher 2012).…”

Section: Background On Different Types Of Geothermal Utilizationsmentioning

confidence: 99%

“…Shallow geothermal energy refers to systems frequently using heat pumps for exploitation of near-surface environments characterized by temperatures <20°C and depths <400 m (Stober et al 2009). Deep geothermal energy refers to direct use of geothermal heat at temperatures >20°C (Líndal 1973;Saadat et al 2010). Major applications are in spas and swimming pools for balneological purposes; in industry, for process heating, in agriculture for greenhouse or soil heating or in aquaculture for pond heating.…”

Section: Background On Different Types Of Geothermal Utilizationsmentioning

confidence: 99%

Exploration for deep geothermal reservoirs in Luxembourg and the surroundings - perspectives of geothermal energy use

Schintgen

2015

Geotherm Energy

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Background: The aim of this paper is to combine different types of information necessary for a first rather qualitative assessment of deep geothermal reservoirs in the region of Luxembourg. Within the geological framework, the study area encompasses Luxembourg and the surrounding areas of Belgium, Germany, and France. On the one hand, the focus is laid on low-enthalpy hydrothermal reservoirs in Mesozoic aquifers in the Trier-Luxembourg Embayment. On the other hand, petrothermal reservoirs in the Devonian basement of the Ardennes and Eifel regions are considered for exploitation by Enhanced/Engineered Geothermal Systems (EGS). Methods: For geothermal exploration and exploitation purposes, geological, thermal, hydrogeological and structural data are necessary. Results: Among the Mesozoic aquifers, the Buntsandstein aquifer characterized by temperatures of up to 50°C is a suitable hydrothermal reservoir that could be exploited by means of heat pumps or provide direct heat for various applications. The most promising area is the zone of the SE-Luxembourg Graben. The aquifer is the warmest underneath the upper Alzette valley and the limestone plateau in Lorraine, where the Buntsandstein aquifer lies below a thick Mesozoic cover. At the base of an inferred Rotliegend graben in the same area, temperatures of up to 75°C are expected. However, geological and hydraulic conditions are uncertain. In the Lower Devonian basement, thick sandstone-/quartzite-rich formations with temperatures >90°C are expected at depths >3.5 km and likely offer the possibility of direct heat use. The setting of the Südeifel (South Eifel) region, including the Müllerthal region near Echternach, as a tectonically active zone may offer the possibility of deep hydrothermal reservoirs in the fractured Lower Devonian basement. Based on recent data on the structure of the Trier-Luxembourg Basin, the new concept presents the Müllerthal-Südeifel Depression as a Cenozoic tectonic structure that is still mobile and relevant for geothermal exploration. Conslusion: Beyond direct use of geothermal heat, the expected modest temperatures at 5 km depth (about 120°C) and increased permeability by EGS in the quartzite-rich Lochkovian could prospectively enable combined geothermal heat production and power generation in Luxembourg and the western realm of the Eifel region.

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“…However, for ORC cycles, unlike steam cycles, where the cycle designer has a great deal of choice in the shape of the T-s diagram of the fluid selected the reheat cycle loses its attractiveness and benefit. Indeed, the reheat cycle is not generally mentioned in geothermal texts (DiPippo, 2012;Saadat et al, 2010;Watson, 2013) and it was found that the cycle efficiency was similar to the basic Rankine cycle (Mago et al, 2007).…”

Section: Reheat Orcmentioning

confidence: 99%

Design optimisation of an Australian EGS power plant using a natural draft dry cooling tower

Duniam¹

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Enhanced Geothermal Systems (EGS) technology was successfully demonstrated in theAustralian context with the operation of the Habanero 1MW pilot plant. This project aims to determine the optimum power plant design for the geothermal parameters found at the Habanero pilot plant. In order to achieve this, a techno-economic optimisation of an Organic Rankine Cycle (ORC) was undertaken.The EGS conditions used in this work are a brine production well head temperature of 220 o C, and minimum brine temperature of 80 o C in order to limit scaling formation in the brine heat exchanger(s). The production well head pressure is 35 MPa and the required reinjection pressure is 45 MPa in order to maintain the desired mass flow rate of 35 kg/s through the EGS resource.A significant source of parasitic power consumption in ORC systems occurs in the condensing system. In order to avert this parasitic power consumption Natural Draft Dry Cooling Towers (NDDCTs) were investigated as the condenser for the ORC. A one dimensional NDDCT model was developed and integrated into the cycle design process to analyse and design for the coupled nature of NDDCT performance with the power cycle. As a base for comparison a one dimensional Mechanical Draft Air Cooled Tower (MDACT) model was developed and each cycle was also analysed with MDACT as the condenser.A wide range of organic working fluids and several cycle configurations were evaluated in the preliminary analysis using a simplified NDDCT model. The cycles were optimised for maximum net power generation and the highest performing cycle configurations were progressed to the techno-economic design point optimisation stage. The cost of each of the major equipment items in the plant was estimated using cost correlations based on historical equipment cost data. The condensing system geometry for both NDDCT and MDACT, heat exchanger geometry and cycle parameters were optimised to find the lowest Specific Investment Cost (SIC) in AUD/kWe for each candidate cycle. The cycle configurations with the lowest SIC from the design point analysis were evaluated across the range of ambient temperatures expected at the site. The mean annual net power generation for each cycle was calculated based on site temperature data and this was used in determining the annualised SIC values, the measure by which the optimum plant configuration was selected. IIThe recuperated, regenerative and basic ORCs were found to be the cycles that obtained the highest net power generation in the preliminary analysis with butane, butene, isobutene, R152a, isobutane, R123 and isopentane the highest performing fluids. The highest net power generation found in the preliminary analysis was 2.688 MWe.The NDDCT model developed in IPSEpro was investigated in isolation to find the optimum design configuration which gives the lowest SICcd, in AUD/kWth of heat rejected. The tower geometry ratios selected were: aspect ratio (tower height / base diameter) of 1.4, diameter ratio (outlet diameter / base diameter) of 0.7, and / 3 (the p...

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Energetic Use of EGS Reservoirs

Cited by 11 publications

References 41 publications

Geochemical and Process Engineering Challenges for Geothermal Power Generation

Geochemical and Process Engineering Challenges for Geothermal Power Generation

Exploration for deep geothermal reservoirs in Luxembourg and the surroundings - perspectives of geothermal energy use

Design optimisation of an Australian EGS power plant using a natural draft dry cooling tower

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