Multiple Use Assessment of the Madrid Basin (Spain) Geothermal Potential

Abstract

The Madrid Basin enjoys one of the most favorable geothermal environments identified in Spain to date. The “Grand Madrid” area (ca 1500 km2) at the northern edge of the Tajo sedimentary basin consists of a thick multilayered sequence of tertiary detritic sandstone overlying a Mesozoic crystalline basement.
Based on available geophysical and deep drilling data and present and future demand patterns, the geothermal potential of the area has been assessed to a depth of 5000 m. This study was based on the volumetric assessment method currently practiced by the oil and mineral industries and addressed four resource and utilization classes:
i. Shallow depth (0-200 m, 20-25°C) applications of ground coupled – ground water heat pumps (GCHP-GWHP),
ii. Medium depth (500-1000; 30-35°C) heat pump assisted applications,
iii. Deep (1500-2500m, 70-90°C) applications for geothermal district heating and cooling (GDHC) systems,
iv. Frontier, ultra-deep (3500-5000 m), applications for combined heat and power (CHP) enhanced geothermal systems (EGS).

The amount of exploitable energy was estimated to be ca. 7.3 1017 J (730 PJ) over a 75 year lifespan according to existing and foreseeable technology standards and market demand, which represents less than 5% of the recoverable heat potential.