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Coupling geothermal direct heat with agriculture
Published in Jochen Bundschuh, Barbara Tomaszewska, Geothermal Water Management, 2018
Jochen Bundschuh, Barbara Tomaszewska, Noreddine Ghaffour, Ihsan Hamawand, Hacene Mahmoudi, Mattheus Goosen
Energy efficiency and good economics are crucial in the development of geothermal greenhouse systems. Results of studies on achieving energy-efficient buildings may be translated to agricultural greenhouses. Angrisani et al. (2016), for example, performed a dynamic simulation to evaluate the energy and economic performance of a novel heating and cooling system based on the coupling between a low or medium-enthalpy geothermal source and an air-handling unit, including a desiccant wheel. This has applications in space heating and domestic hot water, as well as agricultural uses. During the summer season, a downhole heat exchanger supplied heat to regenerate the desiccant material, while geothermal fluid was continuously extracted by the well in order to maintain high operating temperatures (Fig. 11.9). Simultaneously, the extracted geothermal fluid drove an absorption chiller, producing chilled water to the cooling coil of the airhandling unit. Conversely, during the winter season, geothermal energy was used to cover the space heating demand. The results of the simulations show that the novel geothermal heating and cooling system can be extremely profitable in terms of energy and economic performance. Zhou et al. (2016) achieved energy-efficient buildings via retrofitting existing buildings using a case study. It can be speculated that greenhouses could also be retrofitted with geothermal energy sources in order to improve energy efficiency.
Environmental and human health impacts of geothermal exploitation in China and mitigation strategies
Published in Critical Reviews in Environmental Science and Technology, 2023
Yuanan Hu, Hefa Cheng, Shu Tao
For the geothermal reservoirs with high permeability, extraction of geothermal energy using the traditional production-reinjection doublet systems is preferred (Willems et al., 2017), although reinjection can often be more challenging than production (Seibt & Kellner, 2003). To elminate the need for fluid reinjection, various single-well systems have been developed. In downhole heat exchanger (DHE) systems, heat is transferred from the geothermal fluid to the working fluid in a loop (typically U tube or coaxial tube-in-tube) located in the well, and the working fluid circulates between the reservoir and surface in closed-loop for power generation or space heating (Figure S7c). For the low-permeability geothermal reservoirs, borehole heat exchanger (BHE) systems have been developed for thermal energy extraction (Rivera et al., 2015). The heat exchangers in such systems are installed inside a borehole and heat exchange occurs between the underground rock mass and the working fluid (Figure S7d), and their energy supply is typically an order of magnitude lower than that based on DHEs (Le Lous et al., 2015). BHE systems allow the exploitation of low-temperature heat of rock mass without requiring geothermal fluids, and can be constructed almost everywhere (Le Lous et al., 2015; Zhao et al., 2020).