Person: Araiz Vega, Miguel
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Araiz Vega
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Miguel
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IngenierĆa
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0000-0002-7674-0078
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811140
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Publication Open Access Experimental evidence of the viability of thermoelectric generators to power volcanic monitoring stations(MDPI, 2020) CatalĆ”n Ros, Leyre; Garacochea SĆ”enz, Amaia; Casi SatrĆŗstegui, Ćlvaro; Araiz Vega, Miguel; Aranguren Garacochea, Patricia; Astrain Ulibarrena, David; Ingeniaritza; Institute of Smart Cities - ISC; IngenierĆaAlthough there is an important lack of commercial thermoelectric applications mainly due to their low efficiency, there exist some cases in which thermoelectric generators are the best option thanks to their well-known advantages, such as reliability, lack of maintenance and scalability. In this sense, the present paper develops a novel thermoelectric application in order to supply power to volcanic monitoring stations, making them completely autonomous. These stations become indispensable in any volcano since they are able to predict eruptions. Nevertheless, they present energy supply difficulties due to the absence of power grid, the remote access, and the climatology. As a solution, this work has designed a new integral system composed of thermoelectric generators with high efficiency heat exchangers, and its associated electronics, developed thanks to Internet of Things (IoT) technologies. Thus, the heat emitted from volcanic fumaroles is transformed directly into electricity with thermoelectric generators with passive heat exchangers based on phase change, leading to a continuous generation without moving parts that powers different sensors, the information of which is emitted via LoRa. The viability of the solution has been demonstrated both at the laboratory and at a real volcano, Teide (Canary Islands, Spain), where a compact prototype has been installed in an 82 C fumarole. The results obtained during more than eight months of operation prove the robustness and durability of the developed generator, which has been in operation without maintenance and under several kinds of meteorological conditions, leading to an average generation of 0.49W and a continuous emission over more than 14 km.Publication Open Access Prospects of autonomous volcanic monitoring stations: experimental investigation on thermoelectric generation from fumaroles(MDPI, 2020) CatalĆ”n Ros, Leyre; Araiz Vega, Miguel; Padilla, GermĆ”n D.; HernĆ”ndez, Pedro A.; PĆ©rez, Nemesio M.; GarcĆa de la Noceda, Celestino; Albert, JosĆ© F.; Astrain Ulibarrena, David; Ingeniaritza; Institute of Smart Cities - ISC; IngenierĆaFumaroles represent evidence of volcanic activity, emitting steam and volcanic gases at temperatures between 70 and 100 Ā°C. Due to the well-known advantages of thermoelectricity, such as reliability, reduced maintenance and scalability, the present paper studies the possibilities of thermoelectric generators, devices based on solid-state physics, to directly convert fumaroles heat into electricity due to the Seebeck effect. For this purpose, a thermoelectric generator composed of two bismuth-telluride thermoelectric modules and heat pipes as heat exchangers was installed, for the first time, at Teide volcano (Canary Islands, Spain), where fumaroles arise in the surface at 82 Ā°C. The installed thermoelectric generator has demonstrated the feasibility of the proposed solution, leading to a compact generator with no moving parts that produces a net generation between 0.32 and 0.33 W per module given a temperature difference between the heat reservoirs encompassed in the 69ā86 Ā°C range. These results become interesting due to the possibilities of supplying power to the volcanic monitoring stations that measure the precursors of volcanic eruptions, making them completely autonomous. Nonetheless, in order to achieve this objective, corrosion prevention measures must be taken because the hydrogen sulfide contained in the fumaroles reacts with steam, forming sulfuric acid.Publication Open Access Experimental development of a novel thermoelectric generator without moving parts to harness shallow hot dry rock fields(Elsevier, 2022) AlegrĆa CĆa, Patricia; CatalĆ”n Ros, Leyre; Araiz Vega, Miguel; RodrĆguez GarcĆa, Antonio; Astrain Ulibarrena, David; Ingeniaritza; Institute of Smart Cities - ISC; IngenierĆaNowadays, geothermal energy in shallow hot dry rock fields is not exploited enough due to the high economic and environmental impact as well as the lack of scalability of the existing technologies. Here, thermoelectricity has a great future potential due to its robustness, absence of moving parts and modularity. However, the efficiency of a thermoelectric generator depends highly on the heat exchangers. In this work, a novel geothermal thermoelectric generator is experimentally developed, characterizing different configurations of biphasic heat exchangers to obtain low thermal resistances that allow the maximum efficiency in the thermoelectric modules. As a result, robust and passive heat exchangers were obtained with thermal resistances of 0.07 K/W and 0.4 K/W in the hot and cold sides, respectively. The geothermal thermoelectric generator was built with the most effective heat exchangers and was experimented under different temperature and convection conditions, generating 36 W (17 W by a prototype with 10 modules and 19 W by a prototype with 6 modules) for a temperature difference of 160 Ā°C between the heat source and the environment. Furthermore, the experimental development showed that it is possible to increase electricity generation with a more compact generator, since a decrease in the number of modules from 10 to 6 increases the efficiency from 3.72% to 4.06%. With this research, the feasibility of a novel and robust geothermal thermoelectric generator whose working principle is phase change has been experimentally demonstrated, as well as the importance of compactness to maximize its efficiency and thus, power generation.Publication Open Access Experimental development of a novel thermoelectric generator without moving parts to harness shallow hot dry rock fields(2021) AlegrĆa CĆa, Patricia; RodrĆguez GarcĆa, Antonio; CatalĆ”n Ros, Leyre; Astrain Ulibarrena, David; Araiz Vega, Miguel; IngenierĆa; Institute of Smart Cities - ISC; IngeniaritzaNowadays, geothermal energy in shallow hot dry rocks is not exploited enough due to the high economic and environmental impact as well as the lack of scalability of the existing technologies. Here, thermoelectricity has a great future potential due to its robustness, absence of moving parts and modularity. With this research, the feasibility of a novel and robust geothermal thermoelectric generator whose working principle is phase change has been experimentally demonstrated, as well as the importance of compactness to maximize its efficiency and thus, power generation.Publication Open Access Field test of a geothermal thermoelectric generator without moving parts on the Hot Dry Rock field of Timanfaya National Park(Elsevier, 2023) CatalĆ”n Ros, Leyre; AlegrĆa CĆa, Patricia; Araiz Vega, Miguel; Astrain Ulibarrena, David; Institute of Smart Cities - ISC; Universidad PĆŗblica de Navarra / Nafarroako Unibertsitate PublikoaAlthough in the last years thermoelectric generators have arisen as a solution to boost geothermal power generation, tests on field are still scarce. The vast majority of the available studies focus on computational simulations or laboratory experiments, mainly with active heat exchangers that require pumps or fans, and, consequently, present moving parts and auxiliary consumption. The present paper demonstrates for the first time the suitability of a geothermal thermoelectric generator (GTEG) with passive phase change heat exchangers, and therefore, without moving parts nor auxiliary consumption, on the shallow Hot Dry Rock (HDR) field of Timanfaya National Park (Canary Islands, Spain), where 173 Ā°C air anomalies can be found. The device has been in operation without maintenance for 2 years now, producing more than 520 kWh of energy. In terms of power generation, since the installed device is in turn composed of two prototypes with 10 and 6 thermoelectric modules, it has been confirmed that installing more modules leads to a lower generation per module, although total generation can be higher. In fact, the prototype with 10 thermoelectric modules generated a maximum of 20.9 W (2.09 W per module) with a temperature difference between sources of 158 Ā°C, while the prototype with 6 thermoelectric modules obtained 16.67 W (2.78 W per module) under the same conditions. These results open the door for a large-scale exploitation thanks to the intrinsic advantages of modularity, reliability, robustness, and minimal environmental impact of the developed device.