Avaluació del potencial geotèrmic de baixa entalpia al municipi de Lleida a partir de dades de perforacions històriques del subsol

Abstract

The transition towards a decarbonized energy model requires diversifying renewable sources to reduce dependency on critical materials. This master’s thesis evaluates the potential of low-enthalpy geothermal energy in Lleida, addressing the technical challenges that caused the failure of the 1987 deep geothermal project “GeoLleida”. As opposed to this precedent, the present work focuses on a closed-loop, shallow geothermal system, coupled to a heat pump in a buildable plot in the Ciutat Jardí neighborhood (climate zone D3). Through detailed geological and climatic analyses, the subsoil thermal properties and building loads were calculated. The results show that, while the peak heating load in the worst-case scenario (7,12 kW) falls below the peak cooling load (11,73 kW), the annual heating demand (11.878,05 kWh) is higher than the annual cooling demand (8467,89). Consequently, this heating mode determines the heat pump model, and the depth of the geothermal borehole (76,81 m). Furthermore, an economic feasibility analysis was conducted comparing the geothermal heat pump system to a traditional heating and cooling system, constituted by a gas boiler and a split air conditioning unit. Given that the useful life of the conventional system is shorter (20 years) than the heat pump’s (25 years), this analysis was conducted comparing the Equivalent Annual Costs (EAC) for each system, under different discount rates and several energy price increase scenarios. This analysis proved that even though the heat pump system had much higher investment costs (CAPEX), its lower operation and maintenance costs (OPEX) made it a more economically viable option than the traditional system in most scenarios.