Sustainable Sizing of Geothermal Power Plants: Appropriate Potential Assessment Methods

Abstract

The paper analyzes the problem of defining the potential of geothermal reservoirs and the definition of a sustainable size of a geothermal power plant in the preliminary design phase. While defining the size of a geothermal plant, the objective is to find a compromise between renewability, technical sustainability, and economic return-related issues. In the first part of the paper the simplified lumped parameter approach based on the First-Order methods and their further evolutions and limitations is proposed. Experimental data available for some geothermal reservoirs are used for critical analysis of the simplified approaches for estimating the renewability and sustainability of the production of geothermal plants. In the second part the authors analyze methods based on theoretical heat transfer analysis supported by experimental data acquired from the geothermal field (thermal properties of the rock, porosity of the reservoir, and natural heat flux) and finally consider the numerical simulation as a method to connect the two approaches discussed before. The sustainability of geothermal power production can be estimated taking into account the energy stored in the reservoir and the thermal and fluid dynamic analysis of the reservoir. From this perspective, the numerical simulation of the reservoir can be considered as an effective method for the estimation of a sustainable mass flow rate extraction. Some specific cases are analyzed and discussed.

Case Study of Using the Geothermal Potential of Mine Water for Central District Heating—The Rožná Deposit, Czech Republic

“…This geological structure of the deposit subsequently defines the thermal conductivity coefficient of the rocks [32][33][34]. The rock mass of the Rožná deposit exhibits a pronounced rock anisotropy, which is significantly reflected in the thermal conductivity of the rocks, e.g., the thermal conductivity of fine-grained paragneiss is considerably higher than that of gabbro-diorites [35].…”

Review of Recent Drilling Projects in Unconventional Geothermal Resources at Campi Flegrei Caldera, Cornubian Batholith, and Williston Sedimentary Basin

“…Results obtained from drilling projects at key locations can be applied to other areas worldwide [10]. Moreover, since the installed costs and capacity factors of geothermal power plants are projectspecific, often the drilling of additional production wells is required to adjust the extraction mass flow rate and ensure the sustainability of the resource [11]. Deep drilling and reservoir stimulation can generate a negative social perception of geothermal energy within the communities living close to these kind of projects.…”

Nested Shallow Geothermal Systems

“…The contribution of this paper in defining novel management strategies of shallow geothermal thermal impacts poses an advancement in the environmental performance of geothermal technology in comparison to other renewable energy systems [32], thus providing long-term sustainable designs of geothermal systems [33]. Furthermore, the nested geothermal systems concept conforms new possibilities in future sustainable development in urban areas [34].…”