| Authors |
Eléonore DALMAIS, Albert GENTER, Ghislain TRULLENQUE, Eric LEOUTRE, Bernd LEISS, Kristian BÄR, Andre-Charles MINTSA, Dagur Ingi OLAFSON, Ivan RAJSL, Bianca WAGNER |
| Keywords |
EGS, Europe, coproduction, ORC, sedimentary basin, volcanic, cristalline basement, metamorphic basement |
| Abstract |
The MEET Project (Multidisciplinary and multi-context demonstration of EGS exploration and Exploitation Techniques and potential) aims at boosting the use of deep geothermal energy across Europe in various geological contexts (sedimentary, volcanic, metamorphic and crystalline settings) by different approaches. This project, funded under EU Horizon 2020 grant program, has started in May 2018 and should last until October 2021. One main focus of the MEET project consists in a rapid development of deep geothermal energy by optimizing the usage a wide variety of existing wells. As drilling costs represent a huge part of investment for deep geothermal projects, the reuse of existing wells will enable a fast penetration of geothermal energy all across Europe and diminish its Levelized Cost of Energy (LCOE). For this purpose, the MEET team will demonstrate the valorization of geothermal energy in different contexts: • In sedimentary basin, MEET will take advantage of existing oil wells in the Paris and Aquitanian basins to perform experiments on wells and depot sites in order to enhance heat and electricity valorization. Regulatory aspects of oil to geothermal conversion will be studied in order to ensure its feasibility and wider deployment. Economic scenarios will be established to evaluate the financial opportunities this conversion could represent. • At existing EGS sites, MEET will optimize reinjection temperature in order to valorize additional calories. On the Soultz-sous-Forêts geothermal plant, experiments will be conducted in order to lower reinjection temperature from 70°C to 40°C. The impact of this temperature change will be investigated in terms of corrosion and scaling issues in the surface facility as well as the reservoir changes at depth. For this second purpose, in addition to standard seismological monitoring, a fiber optic will be deployed in an observation well to continuously monitor in time and depth the pressure and temperature evolution. • At existing volcanic sites, MEET will optimize low temperature calories by testing a new mobile ORC that could use heat with an input temperature ranging from 70°C to 90°C. In addition to an installation in Reykjanes, a well known geothermal power plant in Iceland, this ORC will be also deployed at a local farm, thus increasing drastically the potential users of such equipment. A specific attention will be payed to the choice of the appropriate material for the heat exchanger in order to avoid corrosion issues. • More generally, this type of mobile ORC will be deployed on 6 sites to show its usability in a wide range of geothermal context. In addition to previously mentioned sites, another granitic site should be also tested. The site is not selected yet but will probably represent thermal resort where additional heat capacities could be turned into electricity. Another main focus of the MEET project aims at investigating new geological settings where valorization of geothermal potential needs to be proven. This concerns mainly Variscan metamorphic rocks which covers large European areas. For that purpose, the MEET team will approach the geothermal potential by developing structural and lithological conceptual models as well as analyzing the petrophysical, mineralogical and geochemical characteristics of potential reservoir rocks and structures. Two main demo sites have been selected in MEET to conduct these investigations: • Göttingen University campus in Germany, where the district heating system could be converted from a conventional gas based to a geothermal heat supply • Havelange site in Belgium, where an existing gas exploration well provides key data from depths down to 5000 m These investigations will be based on analogue site review and sampling in order to determine typical ranges of parameters to model reservoirs in these geological settings. These models will be used to test different stimulation strategies for further EGS deployments. Stimulation strategies already performed in different crystalline basement will be also reviewed in order to design and perform a new chemical treatment in Cornwall (UK) with custom-made environmentally friendly chemical composite agents. At last, an attempt of generalization of MEET results at European scale will be performed based on a multi-layer GIS approach that combines geological, technical, environmental, regulatory, political and social aspects. This GIS, coupled with an economical decision making support tool, calibrated on demo-sites previously described, should highlight areas were future deep geothermal projects could be developed. |