Xavier GALIEGUE

Lithium, which is an excellent conductor of heat and electricity, became a strategic metal in the past decade due to its widespread use in electromobility and green technologies. The resulting significant increase in demand has revived European interest in lithium mining, leading several countries to assess their own resources/reserves in order to secure their supplies. In this context, we present for the first time a geographically-based and geological compilation of European lithium hard-rock occurrences and deposits with their corresponding features (e.g., deposit types, Li-bearing minerals, Li concentrations), as well as a systematic assessment of metallogenic processes related to lithium mineralization. It appears that lithium is well represented in various deposit types related to several orogenic cycles from Precambrian to Miocene ages. About thirty hard-rock deposits have been identified, mostly resulting from endogenous processes such as lithium-cesium-tantalum (LCT) pegmatites (e.g., Sepeda in Portugal, Aclare in Ireland, Läntta in Finland), rare-metal granites (RMG; Beauvoir in France, Cinovec in the Czech Republic) and greisen (Cligga Head, Tregonning-Godolphin, Meldon in the UK and Montebras in France). Local exogenous processes may result in significant Li- enrichment, such as jadarite precipitation in the Jadar Basin (Serbia), but they are rarely related to economic lithium grades such as in Mn-(Fe) deposits, or in bauxite. We also identified major common parameters leading to Li enrichment: 1) a pre-existing Li-bearing source; 2) the presence of lithospheric thickening, which may be a favorable process for concentrating Li; 3) a regional or local extensional regime; and 4) the existence of fractures acting as channel ways for exogenous processes. Furthermore, we point out the heterogeneity of knowledge for several orogenic settings, such as the Mediterranean orogens, suggesting either a lack of exploration in this geographical area, or significant changes in the orogenic parameters.

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Combining geothermal energy and CCS (Carbon Capture and Storage) is a technological solution that uses the same aquifer to provide heat and to store CO2, after dissolving it into the brine, leading to a close loop, as proposed in the CO2-DISSOLVED concept. This technology is more relevant for small-scale emitters-such as biorefineries-than CCS with postcombustion and storage at a supercritical state, which requires larger scale effects i.e., most power generation plants using fossil fuels. Based on a techno-economic analysis, we provide insights on the role of CO2-DISSOLVED in the sustainable transition. Contrary to conventional CCS on fossil fuels, CO2-DISSOLVED appears as a bridge towards renewable energies, and acts as a complementary technology, enlarging the potential of CCS for small or medium industrial emitters. This innovation enriches the portfolio of CCS combinations with renewable energies, like BECCS (BioEnergies and CCS). It helps then to overcome the current debates CCS versus renewable energies, showing a large gradient of situations. According to the Multi-Level Perspective (MLP) of sustainable transition, CO2-DISSOLVED could contribute to the transformation of the existing socio-technical system, and to its reconfiguration towards renewable sources of energy. As other competing technologies, it could play a rising role in the modification of the energy system. Then, focusing only on CCS implemented on large-scale emitters constitutes a narrow vision of CCS potential in the sustainable transition.

This paper presents a method to estimate the technical and economic feasibility of capturing and geologically storing CO 2 resulting from biomass fermentation. The methodology is applied to the case of bio-refineries in the Paris Basin, France. The first step is to build a 3D geological model of the area studied and to choose the optimal injection location from geological and environmental constraints. Then, based on this information, the design of the CCS system (pipeline length, number and type of wellbores, surface equipment ...) and the estimation of the technical feasibility (sufficient storage capacity, risk analysis and management ...) can be performed. The last step is the estimation of the environmental benefits of this system (through a carbon and energy footprint) and its economic long term feasibility thanks to a discounted cash flow analysis. The impact of geological constraints on the economic feasibility of the system is estimated through a sensitivity assessment on the number of required injection wellbores

This paper first focuses on the environmental benefits of the CCS system applied to a bio-ethanol distillery before estimating its feasibility under geological and economic constraints. First, the calculation of CO2 balance in this application shows that the introduction of CO2 capture and storage in biomass energy systems (B-CCS) can significantly increase the CO2 abatement potential of the system and even leads to negative carbon emissions. Besides, a preliminary geological investigation reveals that the studied area has a good storage potential although the presence of major faults, while the low capture costs of CO2 from biomass fermentation emphasize the economic potential of such a solution.

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According to the different climate change roadmaps (IEA, IPCC), Carbon Capture Storage (CCS) will play a key role in the climate change mitigation policy. Its development raises a trade-off between the deployment of large-scale projects (learning by replication), and the preservation of a large portfolio of competing technologies (learning by diversity), on each of its steps (capture, transport, storage). By now large-scale CCS projects are still few, most devoted to EOR (Enhanced Oil Recovery). Although EOR has provided a first feasible business model for CCS, CCS has still to prove its economic viability on a large variety of carbon emitters (power plant, industrial and bioenergy sources). A competing business model for CCS is to find other carbon uses and energy sources, better adapted to medium and small carbon sources. The paper presents such a technological solution, the CO2 DISSOLVED project, which combines CCS in a dissolved state with geothermal energy.

Si les innovations environnementales vont être amenées à jouer un rôle décisif dans les transitions énergétiques, leur mise en oeuvre n'a rien de spontané et nécessite de faire appel à des schémas incitatifs crédibles et des mesures réglementaires fortes. Les techniques en jeu sont en effet lourdes, engageant des externalités de réseau et des économies d'échelle, avec une forte incertitude technique et économique. Dans le domaine des transitions énergétiques le progrès technique peut aboutir ainsi à des " effets de rebond ", l'amélioration de l'efficience énergétique d'une technique pouvant prolonger son utilisation et retarder l'adoption de techniques permettant de réduire plus drastiquement l'intensité en carbone de l'économie. Les techniques de capture et de stockage de carbone, à partir d'énergie fossile (CCS) ou de biomasse (BECCS) apparaissent de ce point de vue comme un moyen de rendre compatible l'utilisation des énergies fossiles avec la réduction des émissions de gaz à effet de serre. Elles n'échappent aux contraintes décrites précédemment, auxquelles il faut ajouter celles pesant sur le prix du carbone évité, sur leur statut réglementaire, et leur acceptabilité. En tout état de cause l'intégration de ces techniques reste une priorité pour les systèmes nationaux d'innovation.

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The setting up of negative emissions appears more and more as a means to achieve the ambitious objectives of future GHG emissions reductions. Capturing, storing and/or valorising CO2 issued from biomass is a promising way to obtain these negative emissions. With this objective, the CO2SERRE project studies the techno-economic and environmental feasibility of implementing an innovative "BCCUS" pilot in France (Centre-Val de Loire). The concept consists in capturing CO2 from a biomass cogeneration plant in Orléans, valorizing it in local greenhouse farms, and storing the unused CO2 in geological reservoirs in the region. To feed the techno-economic and environmental feasibility assessment, each stage of the CCUS chain has been considered and assessed: capture, transport, geological storage, and use in greenhouses. This paper presents the CO2SERRE project’s final outcomes on the technical feasibility of the process, as well as on its viability on both economic and environmental sides. Dalkia Biomasse Orléans (DBO) facility emits around 80 kt of CO2 per year. Data on the plant process and its emissions have been collected. A post-combustion capture by chemical absorption with monoethanolamine (MEA) is considered. The different options for transporting the captured CO2 have been studied, mapped and optimized. The use of pipelines (with CO2 in supercritical phase) is considered for transport to the storage site, while the truck option is considered for transport of liquefied CO2 to the greenhouses. Based on the current practice of CO2 consumption in greenhouses and the needs of the producers of the region, the potential for captured CO2 use in greenhouse in the Orléans region has been estimated to 10 kt/year. Finally, the underground storage capacity in the geological formations of the Paris Basin has been studied through modelling of reservoir behaviour according to well location and injection rate. The targeted reservoir would be able to store over 1 Mt/year, which is almost equivalent to the total annual emissions of the region Centre-Val de Loire. An environmental assessment has been carried out on the whole capture – transport – storage – utilization chain, using Life Cycle Analysis (LCA). The system with CCUS has been compared to the actual situation without CCUS, and different scenarios has been considered according to the source of energy for capture process (steam from DBO or from a gas-fired power plant; with or without energy valorization of the DBO exhaust gases). The analysis shows that, globally, implementing CCUS in our case study avoids more environmental impacts than it generates. Avoided impacts are higher when the energy for capture comes from DBO, but it generates a gain loss for the operator. Also, valorising the exhaust gases energy is interesting especially when using energy from the gas-fired plant. Concerning valorisation of the CO2 in greenhouses, the outcomes show that the highest the share of valorization compared to storage, the lowest are the environmental impacts. The technico-economic analysis (TEA) of the project assesses the economic viability of the whole concept, in which carbon is considered as an input for growing plants. The TEA valuatesthe overall carbon capture, transport and storage costs of the project, and compares this avoided carbon price with the actual price already paid by local greenhouse operators. While both TEA and LCA take account of a sole carbon source, biomass burning, the CO2SERRE concept could be extended to other sources of carbon coming from biomass use, like beetroot fermentation in sugar refineries. An evaluation of the sensibility of the LCA results from the value of its different parameters is performed: compared time profile and volume of carbon emission by biomass burning and use by greenhouse, transport options, and reservoir types.

To achieve the objective of the Paris Agreement to limit global warming to well below 2ºC, there is a growing need to reduce drastically greenhouse gases emissions and even better to set up also negative emissions. Capturing and storing or valorizing carbon dioxide from biomass origin is a way to obtain negative emissions. The CO2SERRE project investigates techno-economic and environmental feasibility of implementing a "BCCUS" (i.e. CCUS for CO2 of biomass origin) pilot in France, in the Centre-Val de Loire Region. The concept consists in capturing CO2 from a biomass cogeneration plant in Orléans, valorizing it in local greenhouse farms, and storing the unused CO2 in geological reservoirs in the region. In addition to generating negative emissions, this concept promotes local and circular economy. To feed the techno-economic and environmental feasibility assessment, each stage of the CCUS chain is considered and assessed (capture, transport, geological storage, and use in greenhouses). Work carried out so far provides useful insights on technical feasibility of the process. However, the key challenge is the viability of the project on both economic and environmental sides. The LCA and TEA analyses, taking into account the whole CCUS chain, are under development and their outputs will address conditions for feasibility of the CO2SERRE concept. A preliminary assessment of geological storage capacity in the region have shown that targeted reservoir would be able to store the equivalent of the total emissions of the region Centre-Val de Loire. Thus, a longer term perspective for CO2SERRE project is to create a new technical and economic network in the region with platforms gathering CO2 emitter, users and storage.

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The CO2-DISSOLVED project, funded by the ANR (French National Research Agency) is a techno-economic study assessing the feasibility of a new concept combining geothermal energy and CCS (Kervévan et al., 2013). This design combines capture, injection, and storage of dissolved CO2 (rather than supercritical) in a deep saline aquifer with 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.

While the environmental innovations will play a key role in the transition towards a decarbonized economy, their implementation is rather difficult to be realized in advanced economies. The techniques at stake imply for some of them scale and network economies, for others changes in habits and uses, with important technical and economic uncertainties. Developing countries can benefit as latecomers from these innovations without incurring their development costs, but they are reluctant to move towards a more decarbonized economic model if this evolution should reduce their growth and limit their development. From this point of view, mitigation techinques, especially Carbon Capture and Storage techniques, from fossil fuels (CCS) or bioenergy (BCCS) appear to be a promising way to reach stringent greenhouse gas reduction targets. They allow preserve the use of fossil fuels during a transition period towards a more decarbonized energy mix. These techniques are nevertheless submitted to the evolution of mitigation costs, to the regulatory uncertainty and to their social acceptability. Their adoption by developing countries depends moreover crucially on the regulatory framework for avoided carbon emission, and of the availability of a financial support from more advanced countries.

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