Detection of Geothermal Potential Zones Using Remote Sensing Techniques

21 p.The transition towards a new sustainable energy model—replacing fossil fuels with renewable sources—presents a multidisciplinary challenge. One of the major decarbonization issues is the question of to optimize energy transport networks for renewable energy sources. Within the range of renewable energies, the location and evaluation of geothermal energy is associated with costly processes, such as drilling, which limit its use. Therefore, the present research is aimed at applying different geomatic techniques for the detection of geothermal resources. The workflow is based on free/open access geospatial data. More specifically, remote sensing information (Sentinel-2A and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER)), geological information, distribution of gravimetric anomalies, and geographic information systems have been used to detect areas of shallow geothermal potential in the northwest of the province of Orense, Spain. Due to the variety of parameters involved, and the complexity of the classification, a random forest classifier was employed, since this algorithm works well with large sets of data and can be used with categorical and numerical data. The results obtained allowed identifying a susceptible area to be operated on with a geothermal potential of 80 W·m−1 or higherS

Monitoring temporal variations in the geothermal activity of Miocene Lesvos volcanic field using remote sensing techniques and MODIS - LST imagery

Abstract Many islands of the Aegean Sea show strong geothermal activity due to volcanism in the area. In this paper, Robust Satellite Techniques (RST) are used to isolate, from other known possible sources, those thermal anomalies possibly related to geothermal activity in the Miocene volcanic field of Lesvos Island (Northern Aegean). For this purpose, 12 years (2003–2014) of daily Night-time Land Surface Temperature (LST) products, from Moderate Resolution Imaging Spectroradiometer (MODIS) acquisitions were analyzed. The final dataset contained 770 thermal anomalies whose spatial correlation with geological and structural data of Lesvos - such as caldera rims, ring faults, major tectonic lineaments and hydrothermal alterations mapped by processing SENTINEL-2 MSI satellite images – has been particularly investigated. In the approximately 20 ma geothermal field of Lesvos, geothermal activity seems to be also associated with the extensional regime of the broader area that leads to lithosphere thinning and consequent heat transfer in the multi-fractured terrain of Lesvos through volcanic and tectonic faults. Achieved results seem to confirm the possibility to use RST-based thermal anomalies to identify temporal variations in the geothermal activity probably due to the uplifting and circulation of the hydrothermal waters

Kontrol Struktur Geologi Terhadap Potensi Panas Bumi Daerah Danau Ranau, Sumatera Selatan dan Sekitarnya

Reduksi ketersediaan energi konvensional menuntut pengembangan energi alternatif, salah satunya panas bumi. Danau Ranau memiliki potensi panas bumi direpresentasikan dengan manifestasi mata air panas di permukaan. Sasaran identifikasi awal potensi panas bumi terkait asosiasinya dengan struktur rekahan dan patahan. Observasi ini dikembangkan dengan studi pustaka, penginderaan jauh dengan pendekatan melalui satelit citra, survei manifestasi, dan analisis studio. Berdasarkan analisis ini didapati pola kelurusan dominan barat laut – tenggara dan dipengaruhi oleh gaya kompresi dengan arah relatif utara – selatan. Pola kelurusan ini berasosiasi dengan struktur geologi sebagai play zone dari reservoir geothermal. Tipe kelurusan juga diinterpretasikan bahwa Danau Ranau merupakan discharge zone yang dihasilkan oleh sesar mendatar yaitu Sesar Kumering dengan pola serupa Sesar Semangko. Hasil survei permukaan ditemukan dua lokasi manifestasi Air Panas Ranau (APR) dan Air Panas Lumbok (APL). Lokasi APR ditemukan dua titik manifestasi dengan suhu sekitar 54o C dan 60o C, kadar pH netral, dan litologi penyusun batuan sampingnya berupa endapan piroklastik yaitu welded tuff dan batuan beku andesit. Pada APL terdapat dua titik manifestasi air panas dengan suhu sekitar 45o C hingga 59o C dengan pH relatif netral. Potensi energi sekitar 37 Mwe diduga terdapat pada reservoir panas bumi pada daerah Danau Rana

Analisis Potensi Panas Bumi Menggunakan Landsat 8 dan Sentinel 2 (Studi Kasus : Gunung Ijen)

Energi panas bumi juga merupakan energi panas yang terdapat pada internal bumi (Smaragdenkis, 2016). Sebanyak 252 lokasi panas bumi di Indonesia tersebar mengikuti jalur pembentukan gunung api yang membentang dari Sumatra, Jawa, Nusa Tenggara, Sulawesi sampai Maluku. Dengan total potensi sekitar 27 GWe (Wahyuningsih, 2005). Pemerintah berkeinginan agar pengembangan panas bumi di Indonesia dapat berjalan dengan baik sehingga panas bumi dapat berperan sebagai salah satu pilar ketahaan energi nasional. Hal tersebut terlihat melalui penetapan Peraturan Presiden No. 5 Tahun 2006 tentang Kebijakan Energi Nassional (KEN). Dalam Perpres tersebut, Pemerintah menargetkan kontribusi energi panas bumi pada tahun 2025 sebesar 9500 MW. Namun potensi panas bumi di Indonesia hanya 4% potensi yang telah dimanafaatkan. Salah satu lokasi poetensi panas bumi adalah Gunung Ijen. Kompleks Gunung Ijen adalah gunung api yang mempunyai danau kawah dengan kedalaman sekitar 190 m dan mempunyai derajat keasaman yang sa ngat tinggi (pH < 0,2) serta volume air danau yang sangat besar, sekitar 36 juta m3 (Irfandy, 2012). Dengan melimpahnya potensi potensi panas bumi di Indonesia maka perlu adanya suatu kegiatan yang berupa kajian geosains terpadu untuk dapat memaksimalkan kandungan potensi yang ada disuatu wilayah panas bumi. Salah satu kajian yang dilakukan adalah melakukan pemetaan potensi. Adapun penelitian ini melakukan pengolahan data citra Landsat 8, Sentinel 2, Peta RBI, dan data survei pendahuluan pada Kawasan Gunung Ijen. Penelitian ini melakukan pengolahan Indeks Vegetasi, suhu permukaan dan ketinggian. Peralatan yang digunakan dalam penelitian ini meliputi software pengolah citra, software pengolah angka, GPS Handheld untuk pengambilan koordinat di lapangan dan Laptop. Suhu Permukaan pada daerah Gunung Ijen memiliki anomali dengan besar suhu berkisar anatara 18o C hingga 38o C. Nilai korelasi terbaik dari ketinggian dan suhu permukaan tanah adalah -0,89 yaitu korelasi suhu permukaan bulan Januari. Sedangkan nilai uji korelasi indeks vegetasi Landsat 8 dan Sentinel 2 adalah 0,81. Matriks konfusi tutupan lahan memperoleh nilai sebesar 80%. Tutupan lahan pada daerah penelitian didominasi oleh hutan sebesar 35% dari luas wilayah penelitian. Terdapat wilayah potensi potensi panas bumi sangat tinggi pada Gunung Ijen dengan luas 39,43 Ha yang terletak pada kecamatan Wongsorejo dan berbatasan dengan Kecamatan Sempol. ================================================================= Geothermal energy is also a heat energy found in the earth's internal (Smaragdenkis, 2016). A total of 252 geothermal locations in Indonesia are scattered following the path of volcanic formation that stretches from Sumatra, Java, Nusa Tenggara, Sulawesi to Maluku. With a total potential of around 27 GWe (Wahyuningsih, 2005). The government is eager for the development of geothermal in Indonesia can run well so that geothermal can act as one of the pillars of national energy. It is seen through the stipulation of Presidential Regulation no. 5 of 2006 on Nassional Energy Policy (KEN). In the Presidential Regulation, the Government is targeting geothermal energy contribution in 2025 of 9500 MW. However, geothermal potential in Indonesia is only 4% of potential that has been utilized [4]. One of the geothermal hotspots is Mount Ijen. Mount Ijen Complex is a volcano that has a crater lake with a depth of about 190 m and has a very high degree of acidity (pH <0.2) and the volume of lake water is very large, about 36 million m3 (Irfandy, 2012). With the abundance of potential geothermal potential in Indonesia, it is necessary to have an activity in the form of integrated geoscience studies to be able to maximize the potential content that exists in a geothermal area. One of the studies conducted is to do potential mapping. This research performs image data processing of Landsat 8, Sentinel 2, RBI Map, and preliminary survey data on Gunung Ijen Area. This research carried out the Vegetation Index, surface temperature and altitude. The equipment used in this research includes image processing software, number processing software, GPS Handheld for coordinate on field and Laptop. Surface Temperatures in the Ijen Mountain area have anomalies with large temperatures ranging between 18o C to 38o C. The best correlation value of altitude and ground surface temperature is -0.89 ie the correlation of January surface temperature. While the correlation test value of Landsat 8 and Sentinel 2 vegetation index was 0.81. The land cover confidence matrix scored 80%. Land cover in the research area is dominated by forests by 35% of the research area. There is a potential area of geothermal potential is very high on Mount Ijen with an area of 39.43 hectares located in Wongsorejo sub-district and adjacent to District Sempol

Integrated seismic ambient noise, magnetotellurics and gravity data for the 2D interpretation of the Vallès basin structure in the geothermal system of La Garriga-Samalús (NE Spain)

The integration of geophysical methods, together with the previous information of the Vallès basin area, has resulted in the creation of a new conceptual model that explains La Garriga-Samalús geothermal system. The integration of complementary geophysical methods seems to be a good option for the preliminary stages of a geothermal system exploration, especially in urban areas. An integrated seismic ambient noise, magnetotellurics, and gravity methods were used to determine the geological units and structures which control the La Garriga-Samalús geothermal system. The 2D resistivity and density models have allowed the identification of the four main units which regulate the geothermal system: the Miocene basin, the Prelitoral Range unit, the Vallès Faut Zone, and the Paleozoic basement. The interpretation of our models set the Vallès Fault Zone, which is characterized by an anomalous low resistivity and low density, as the main path for the hot fluids. Moreover, the geophysical characterization established a new geometry for the Miocene basin. The Miocene basin presents a stepwise morphology, with the minor thickness towards the fault and an increasing thickness towards the center of the basin. This geometry seems to be related to synthetic normal faults. These results have evidenced that, although, in some geothermal systems, the warm water may create an insufficient physical contrast; the appropriate use of some techniques can still be useful for the exploration of medium and low-temperature geothermal systems

Geophysical and geological characterization of fault-controlled geothermal systems: The Vallès Basin case of study

[eng] Geothermal energy is a renewable source of energy that harnesses heat from the Earth's interior. Temperature increases with depth, defining the geothermal gradient, which can be variable depending on the geological context. The geological setting of western Europe favors a relatively high geothermal gradient that could be exploited to generate electricity or for its direct use, for example, for its application in industry, greenhouses, or heating systems. In each of these cases, geothermal could favor the community's energy independence and reduce the use of polluting energy sources. To appropriately exploit areas with a significant geothermal gradient, it is essential to know the origin of the temperature anomaly and the system's functioning. In this context, developing appropriate exploration methodologies and techniques is essential for its adequate and efficient use. This thesis develops a methodology focused on a geothermal system type characterized by being located in highly fractured zones. These fractures connect the surface with great depths, allowing the rapid ascent of deep fluids at high temperatures without giving them time to cool down. Specifically, this thesis applies this methodology to a study case located in the Vallès Basin, close to Barcelona city (NE Iberian Peninsula), where some localities, such as La Garriga and Caldes de Montbui towns, have thermal hot springs (60ºC and 70ºC, respectively). In particular, the methodology applied to study the Vallès Basin geothermal fractured system, is focused on two main cores, geophysical and geological techniques. Geophysical methods allow the characterization of the subsurface physical properties, reaching great depths without having to drill. For example, if the physical characteristics of the subsurface have enough contrast, they could allow distinguishing between different types of rocks, fractured zones, or if there is any fluid circulation. However, the geophysical results have to be complemented with other geoscientific studies in order to make a proper interpretation. In this case, this thesis includes a characterization of the area's geology, fracturing, and hydrology. Finally, the integration of the applied techniques has allowed the understanding of the origin and system's functioning, which is presented in the form of a 3D conceptual model, geological model, and temperature model. This innovative methodology, which integrates different geoscientific techniques at different scales, combining traditional techniques with novel digital tools, has facilitated the characterization of a geothermal system controlled by geological structures. Therefore, it is established as a methodical option to characterize systems of similar origin.[cat] La Geotèrmia és una font renovable d'energia que aprofita la temperatura de l'interior de la Terra. El grau en què aquesta temperatura augmenta en profunditat, ve definint pel gradient geotèrmic, el qual pot ser variable segons el context geològic. La geologia de la regió oest del continent europeu afavoreix un gradient geotèrmic relativament alt que podria ser aprofitat per generar electricitat o per a ús directe, com és el cas d'aplicacions en indústria, hivernacles o sistemes de calefacció. En qualsevol cas, la geotèrmia podria afavorir la independència energètica i una disminució en l’ús de fonts d’energia contaminants. Per a un aprofitament d'aquestes zones amb un gradient geotèrmic significatiu, és essencial conèixer-ne l'origen i el funcionament. En aquest context, és basic desenvolupar metodologies d'exploració que siguin adequades i eficients. Aquesta tesis desenvolupa una metodologia aplicada a un exemple de sistema geotèrmic caracteritzat per estar ubicat en una zona molt fracturada. Aquestes fractures connecten la superfície amb grans profunditats, permetent l'ascens ràpid de fluids profunds que es troben a temperatures altes, sense que els doni temps a refredar-se. Concretament, aquesta zona d'estudi es situa a la Conca del Vallès (NE Península Ibèrica), on algunes localitats com La Garriga i Caldes de Montbui, tenen surgències d'aigua termal (60ºC i 70ºC, respectivament). Concretament, la metodologia aplicada es basa en dues parts principals: l'exploració geofísica i la geològica. Els mètodes geofísics ens permeten conèixer les propietats físiques del subsol arribant a grans profunditats sense haver de fer perforacions. Si les característiques físiques del terreny presenten un contrast suficient, poden permetre, per exemple, distingir entre tipus de roques, zones fracturades, o si hi ha circulació d'algun fluid. Tot i així, els resultats geofísics s'han de complementar amb altres estudis geocientífics per una correcta interpretació dels resultats. En aquest cas, aquesta tesis inclou una caracterització de la geologia, la fracturació i la hidrologia de la zona. La integració final de totes les dades ha permès entendre l'origen i el funcionament d'aquest sistema, resultat del qual es presenta en forma d'un model 3D conceptual, geològic i de temperatures. Aquesta metodologia innovadora, que integra diferents tècniques geocientífiques a escala diferent, ha combinat tècniques tradicionals amb eines digitals noves, facilitant la caracterització d'un sistema geotèrmic controlat per estructures geològiques. Per tant, s’estableix com una opció metòdica a seguir per a la caracterització de sistemes d’origen similar.[spa] La Geotermia es una fuente renovable de energía que aprovecha el calor del interior de la Tierra. La temperatura del interior de la Tierra aumenta con la profundidad, y este aumento, definido como gradiente geotérmico, puede ser variable según el contexto geológico. El contexto geológico del oeste del continente europeo favorece un gradiente geotérmico relativamente alto que podría ser aprovechado para generar electricidad o para su uso directo, como es el caso de aplicaciones en industria, invernaderos o sistemas de calefacción. En cualquier caso, la geotermia podría favorecer la independencia energética y una disminución del uso de fuentes de energía contaminantes. Para un apropiado aprovechamiento de estas zonas con un gradiente geotérmico significativo, es esencial conocer su origen y funcionamiento. En este contexto, es necesario un avance en el desarrollo de metodologías de exploración que sean adecuadas y eficientes. Esta tesis desarrolla una metodología aplicada a un tipo de sistema geotérmico caracterizado por estar ubicado en zonas muy fracturadas. Estas fracturas conectan la superficie con grandes profundidades, permitiendo el ascenso rápido de fluidos profundos que se encuentran a altas temperaturas sin que les dé tiempo a enfriarse. Geográficamente, esta zona de estudio se encuentra en la Cuenca del Vallès, cerca de Barcelona (NE Península Ibérica), donde algunas localidades como La Garriga y Caldes de Montbui, tienen surgencias de agua termal (60ºC y 70ºC, respectivamente). Concretamente, esta metodología se puede separar en dos partes principales, la exploración geofísica y la geológica. Los métodos geofísicos nos permiten conocer las propiedades físicas del subsuelo, llegando a grandes profundidades, sin tener que hacer perforaciones. Si las características físicas del terreno presentan un contraste suficiente, nos pueden permitir, por ejemplo, distinguir entre tipos de rocas, zonas fracturadas, o si hay circulación de algún fluido. Aun así, los resultados geofísicos tienen que complementarse con otros estudios geocientíficos para poder hacer una apropiada interpretación. Esta tesis incluye una caracterización de la geología, la fracturación y la hidrología de la zona, cuya integración final ha permitido entender el origen y funcionamiento de este sistema. Los resultados finales se presentan en forma de un modelo 3D conceptual, geológico y de temperaturas. Esta metodología innovadora integra distintas técnicas geocientíficas a distinta escala, combinando técnicas tradicionales con herramientas digitales novedosas, facilitando la caracterización de un sistema geotérmico controlado por estructuras geológicas. Por lo tanto, se establece como una opción metódica a seguir para la caracterización de sistemas de origen similar

Geophysical and geological characterization of fault-controlled geothermal systems: The Vallès Basin case of study

[eng] Geothermal energy is a renewable source of energy that harnesses heat from the Earth's interior. Temperature increases with depth, defining the geothermal gradient, which can be variable depending on the geological context. The geological setting of western Europe favors a relatively high geothermal gradient that could be exploited to generate electricity or for its direct use, for example, for its application in industry, greenhouses, or heating systems. In each of these cases, geothermal could favor the community's energy independence and reduce the use of polluting energy sources. To appropriately exploit areas with a significant geothermal gradient, it is essential to know the origin of the temperature anomaly and the system's functioning. In this context, developing appropriate exploration methodologies and techniques is essential for its adequate and efficient use. This thesis develops a methodology focused on a geothermal system type characterized by being located in highly fractured zones. These fractures connect the surface with great depths, allowing the rapid ascent of deep fluids at high temperatures without giving them time to cool down. Specifically, this thesis applies this methodology to a study case located in the Vallès Basin, close to Barcelona city (NE Iberian Peninsula), where some localities, such as La Garriga and Caldes de Montbui towns, have thermal hot springs (60ºC and 70ºC, respectively). In particular, the methodology applied to study the Vallès Basin geothermal fractured system, is focused on two main cores, geophysical and geological techniques. Geophysical methods allow the characterization of the subsurface physical properties, reaching great depths without having to drill. For example, if the physical characteristics of the subsurface have enough contrast, they could allow distinguishing between different types of rocks, fractured zones, or if there is any fluid circulation. However, the geophysical results have to be complemented with other geoscientific studies in order to make a proper interpretation. In this case, this thesis includes a characterization of the area's geology, fracturing, and hydrology. Finally, the integration of the applied techniques has allowed the understanding of the origin and system's functioning, which is presented in the form of a 3D conceptual model, geological model, and temperature model. This innovative methodology, which integrates different geoscientific techniques at different scales, combining traditional techniques with novel digital tools, has facilitated the characterization of a geothermal system controlled by geological structures. Therefore, it is established as a methodical option to characterize systems of similar origin.[cat] La Geotèrmia és una font renovable d'energia que aprofita la temperatura de l'interior de la Terra. El grau en què aquesta temperatura augmenta en profunditat, ve definint pel gradient geotèrmic, el qual pot ser variable segons el context geològic. La geologia de la regió oest del continent europeu afavoreix un gradient geotèrmic relativament alt que podria ser aprofitat per generar electricitat o per a ús directe, com és el cas d'aplicacions en indústria, hivernacles o sistemes de calefacció. En qualsevol cas, la geotèrmia podria afavorir la independència energètica i una disminució en l’ús de fonts d’energia contaminants. Per a un aprofitament d'aquestes zones amb un gradient geotèrmic significatiu, és essencial conèixer-ne l'origen i el funcionament. En aquest context, és basic desenvolupar metodologies d'exploració que siguin adequades i eficients. Aquesta tesis desenvolupa una metodologia aplicada a un exemple de sistema geotèrmic caracteritzat per estar ubicat en una zona molt fracturada. Aquestes fractures connecten la superfície amb grans profunditats, permetent l'ascens ràpid de fluids profunds que es troben a temperatures altes, sense que els doni temps a refredar-se. Concretament, aquesta zona d'estudi es situa a la Conca del Vallès (NE Península Ibèrica), on algunes localitats com La Garriga i Caldes de Montbui, tenen surgències d'aigua termal (60ºC i 70ºC, respectivament). Concretament, la metodologia aplicada es basa en dues parts principals: l'exploració geofísica i la geològica. Els mètodes geofísics ens permeten conèixer les propietats físiques del subsol arribant a grans profunditats sense haver de fer perforacions. Si les característiques físiques del terreny presenten un contrast suficient, poden permetre, per exemple, distingir entre tipus de roques, zones fracturades, o si hi ha circulació d'algun fluid. Tot i així, els resultats geofísics s'han de complementar amb altres estudis geocientífics per una correcta interpretació dels resultats. En aquest cas, aquesta tesis inclou una caracterització de la geologia, la fracturació i la hidrologia de la zona. La integració final de totes les dades ha permès entendre l'origen i el funcionament d'aquest sistema, resultat del qual es presenta en forma d'un model 3D conceptual, geològic i de temperatures. Aquesta metodologia innovadora, que integra diferents tècniques geocientífiques a escala diferent, ha combinat tècniques tradicionals amb eines digitals noves, facilitant la caracterització d'un sistema geotèrmic controlat per estructures geològiques. Per tant, s’estableix com una opció metòdica a seguir per a la caracterització de sistemes d’origen similar

Impact of geogenic degassing on C-isotopic composition of dissolved carbon in karst systems of Greece

The Earth C-cycle is complex, where endogenic and exogenic sources are interconnected, operating in a multiple spatial and temporal scale (Lee et al., 2019). Non-volcanic CO2 degassing from active tectonic structures is one of the less defined components of this cycle (Frondini et al., 2019). Carbon mass-balance (Chiodini et al., 2000) is a useful tool to quantify the geogenic carbon output from regional karst hydrosystems. This approach has been demonstrated for central Italy and may be valid also for Greece, due to the similar geodynamic settings. Deep degassing in Greece has been ascertained mainly at hydrothermal and volcanic areas, but the impact of geogenic CO2 released by active tectonic areas has not yet been quantified. The main aim of this research is to investigate the possible deep degassing through the big karst aquifers of Greece. Since 2016, 156 karst springs were sampled along most of the Greek territory. To discriminate the sources of carbon, the analysis of the isotopic composition of carbon was carried out. δ13CTDIC values vary from -16.61 to -0.91‰ and can be subdivided into two groups characterized by (a) low δ13CTDIC, and (b) intermediate to high δ13CTDIC with a threshold value of -6.55‰. The composition of the first group can be related to the mixing of organic-derived CO2 and the dissolution of marine carbonates. Springs of the second group, mostly located close to Quaternary volcanic areas, are linked to possible carbon input from deep sources