Jérôme Sterpenich

Using stained glass windows to understand the durability of toxic waste matrices

Abstract Using stained glasses sampled from French and German cathedrals, and from different archaeological sites, this work presents an estimation of the effect of weathering conditions and glass composition on glass dissolution. Due to accurate dating, we also show that stained glass windows allow the determination of the average dissolution kinetics of many toxic elements contained in the glass (including transition and heavy metals, actinides, lanthanides). Therefore, a significant advantage of using stained glass windows, over other natural glasses, is that they permit the direct study of non-stoichiometric elemental dissolution rates, under natural conditions of alteration, averaged over more than a thousand years, and hence to constrain the long-term behaviour of vitrified waste matrices.

CO2-Dissolved - A Novel Approach to Combining CCS and Geothermal Heat Recovery

This paper presents the outline of the CO2-DISSOLVED project whose objective is to assess the technical-economic feasibility of a novel CCS concept integrating geothermal energy recovery, aqueous dissolution of CO2 and injection via a doublet system, and an innovative post-combustion CO2 capture technology. Compared to the use of a supercritical phase, this approach offers substantial benefits in terms of storage safety, due to lower brine displacement risks, lower CO2 escape risks, and the potential for more rapid mineralization. However, the solubility of CO2 in brine will be a limiting factor to the amount of CO2 that can be injected. Consequently, and as another contributing novel factor, this proposal targets low to medium range CO2 emitters (ca. 10-100 kt/yr), that could be compatible with a single doublet installation. Since it is intended to be a local solution, the costs related to CO2 transport would then be dramatically reduced, provided that the local underground geology is favorable. Finally, this project adds the potential for energy and/or revenue generation through geothermal heat recovery. This constitutes an interesting way of valorization of the injection operations, demonstrating that an actual synergy between CO2 storage and geothermal activities may exist.

Six Years of Intensive Research Cooperation to the Lacq-Rousse Pilot of Total - The Academic Point of View from GeoRessources Lab

This paper presents the feedback of 6 years of research programs led by GeoRessources lab of Universite de Lorraine about geochemistry of the Rousse pilot of Total. Intense cooperation between academic labs, EPIC, very small companies, industry, government organizations supported three main research programs covering a wide vertical scale from planetary boundary layer to deep reservoir rock (around 6 km). Main innovative results concern the development of new remote sensors and new completion/sensors combinations for in situ on-line gas measurements. Major research advances show very high natural variations of CO2 with time and soil location, allow the establishment of prediction law for the evolution with time of CO2 content in soil, contribute to geological and geochemical models for reservoir and caprock and describe the mechanisms of oxidation of CH4 and mineralogical assemblages of Rousse reservoir. In the biosphere/atmosphere interface, experimental 3D simulation of natural CO2 envelopes directly above the injection site of Rousse has been developed for the first time. The implication of GeoRessources lab to the Lacq-Rousse pilot research program of Total has produced numerous new geochemical and technical concepts. Such results are transferred to other applications in different domains: security of industrial sites, environment control, and geodynamics of the Pyrenees.

Medieval stained glass: a model for leaching of vitrified wastes

Silicate glasses, because of their abil i ty to i nco rpo ra t e high p r o p o r t i o n s of po l lu t ing elements such as heavy metals or transition elements, represent one of the best matrices for stabilizing and storing industrial or domestic wastes. Nevertheless, these glasses are subject to atmospheric agents or pore waters during their storage or valorization, and may be deteriorated by leaching. Under natural conditions of pH, the polluting elements (Pb, Cu, Zn, Cr...) trapped in the vitreous matrix can be partly leached in aqueous fluids over several decades or several centuries. The result is potential pollution and the impossibility to valorize these vitrified wastes. Thus, a comprehension of the leaching processes of polluting elements in a vitreous matrix and the quantification of their release as a function of time, is a prerequisite for storing or valorization of vitrified wastes. As a complement to experimental studies of leaching, we show that the evaluation of the longevity of vitrified wastes can be tackled by an analogical approach. Although basaltic glasses have already been used as natural analogues, we suggest that the stained glasses of medieval cathedrals dating from the XII to XIVth century are a much more suitable model for the study of the ageing of stabilized glasses. Indeed, these stained glasses not only have a composition very similar to that of the vitrified wastes, but have also undergone conditions of alteration which are probably similar to those envisaged for the waste glasses. The stained glasses studied have compositions rich in silica, calcium and alkalis (see Table). They are very similar to vitrified wastes. This holds not only for major elements, but also for trace and volatile elements. Indeed, their coloration was obtained by adding heavy metals or transition elements whose concentrations are close to those measured in vitrified wastes. Moreover, stained glasses were conserved on windows or were accidentally buried underground. Thus, they allow us to follow the alteration of glass under different condit ions after 600 to 900 years exposure. These glasses show three types of alteration: 1) a meteoric alteration as deduced from a study of the outside of the windows, 2) an alteration by condensation of water as deduced from a study of the inside of the windows, and 3) an alteration by ground waters and humic acids of samples in the soil.