Geothermal Power at Wadi Al-Lith, Saudi Arabia

Saudi Arabia's western Arabian Shield hosts some of the Kingdom's most promising geothermal targets, yet decades of exploration left them described rather than quantified. Wadi Al-Lith, about 200 km southeast of Jeddah, typifies the gap: four hot springs, Ain Al-Harrah, Bani Hilal, Wadi Markub and Al-Darakah, discharge from fractured Precambrian basement at up to 96 °C, but no study had translated the geology into power generation potential across all four. This study delivers the first integrated, probabilistic and uncertainty-bounded assessment covering all four spring systems.

The individual techniques are established; what is new is their coupling into a single re-executable pipeline, in which the temperature returned by the geothermometric step passes automatically to the thermodynamic step, and the fluid properties it returns pass in turn to the stochastic reserve calculation, with no manual transfer of values at any stage. The thermal waters prove to be mature Na-Cl fluids with distinctly low bicarbonate and magnesium and enrichment in lithium, strontium and barium, signalling deep circulation through high heat-generating granites. Reservoir temperatures converge at 90 to 135 °C on two independent routes, and the inferred average heat flow, based on an assumed 2.0 km reservoir depth rather than a gradient well, reaches 106.1 mW/m², close to the 109.8 mW/m² obtained independently for the same area from aeromagnetic Curie-depth analysis. The probabilistic model returns modal power potentials of 3.56 to 5.59 MWe per spring, averaging 4.61 MWe, per assumed 1.0 km³ of reservoir over a 20-year plant life. These are preliminary estimates, not demonstrated reserves: no deep well, reservoir-volume determination or flow test exists for the area, and at this scale the resource suits distributed, small-scale binary generation and direct use rather than utility-scale deployment.