Geochemical impact of re-injecting geothermal waste waters: example, Larderello, Italy
Costanzo Panichi, 2004. "Geochemical impact of re-injecting geothermal waste waters: example, Larderello, Italy", Energy, Waste and the Environment: a Geochemical Perspective, R. Gieré, P. Stille
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The impaccts of re-injection of geothermal waste waters on the physico-chemical characteristics of the fluids of the Larderello vapour-dominated geothermal field in Tuscany (Italy) were monitored using deuterium and oxygen-18 as ‘natural’ tracers. The observed variations were due mainly to mixing between the re-injected and deep components. Large isotopic fractionations occur at depth during the evaporation of the re-injected water in the reservoir and may affect the evaluation of the recovered fluid using a simple mixing model. Stable isotope and gas/steam ratios are closely correlated in the fluid collected from the monitored wells. Maps showing the isotopic distribution of the steam and the distribution of the gas content have been generated for the whole Larderello geothermal field. Evaluation of data collected before and after re-injection reveals a good distinction between natural inflow induced by exploitation, and artificial recharge with waste fluid. Gases other than N2 in the wells affected by injection are substantially diluted since condensates are formed by evaporation. Isotopic variations of H2, CH4, and CO2 have been used to describe the disequilibrium conditions among gas components. This disequilibrium is induced by the settling of a liquid plume at the producing level in the reservoir.
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This book provides incentives for further development of sustainable fuel cycles through a novel and interdisciplinary approach to an Earth science-related topic. The main focus is on geochemical concepts in immobilizing, isolating or neutralizing waste derived from energy production and consumption. The book also addresses the issue of using some types of energy-derived waste as alternative raw materials. Moreover, it highlights research on how certain wastes can be used for energy production, an increasingly important aspect of modern integrated waste management strategies. The main objectives are to: (a) identify the most serious environmental problems related to various types of power generation and associated waste accumulation; (b) present strategies, based on natural analogue materials, for the immobilization of toxic and radioactive waste components through mineralogical barriers; (c) discuss modern procedures for reuse of waste or certain waste components; and (d) review the importance of geochemical modelling in describing and predicting the interaction between waste and the environment.