Integrated assessment of natural hydrogen generation and geothermal energy co-production potential in Syria

Syria’s sedimentary basins and ophiolitic terranes host three co-located subsurface energy processes that have so far been studied in isolation: (i) hydrogen generation by low- to medium-temperature serpentinization of the Baer–Bassit ophiolite in the coastal mountain belt; (ii) hydrogen generation by radiolysis of pore and fracture water driven by the uranium–thorium–potassium decay of the Upper Cretaceous–Paleogene phosphate belt of the Palmyrides; and (iii) radiogenic heat production, locally exceeding 5–8 µW/m³ in phosphorites, which sustains elevated geothermal gradients of 38–45 °C/km in the Euphrates Graben. This study integrates these processes in a single screening framework combining a GIS-based natural-hydrogen atlas (one serpentinization review area and seven radiolysis review areas, compiled from published geological, groundwater and radiometric sources), a re-evaluated inventory of 50 decommissioned hydrocarbon wells, and consistent thermodynamic and levelized-cost modelling. Ten candidate wells passed screening; four case-study wells (2,400–3,100 m, 125–150 °C) were modelled in detail with a Carnot-limited organic Rankine cycle model yielding 2.0–4.5 MW net per well, and the full shortlist 52.7 MW and 392 GWh/yr at a capacity factor of 85%. Screening-level levelized costs of US$0.039–0.051/kWh are below greenfield binary geothermal and unsubsidised natural gas, because well repurposing eliminates 40–60% of conventional project CAPEX. Order-of-magnitude screening estimates suggest the Baer–Bassit system could sustain hydrogen fluxes of roughly 0.6–10 kt/yr (Oman-analog scaling), while radiolysis in the phosphate belt could accumulate 10⁴–10⁵ t H₂ per km³ of phosphorite over 100 Myr under porosity-limited conditions — significant only where long-lived seals exist. No verified hydrogen discovery is claimed: all targets are literature-based review areas, and a staged field programme (soil-gas surveys, groundwater sampling, well re-entry and testing) is proposed. Multi-well scenario economics show that a hybrid cluster re-entering ten existing wells and drilling four deep infill wells (4.5–5.2 km, 210–239 °C) delivers 125 MW at the lowest portfolio levelized cost of the study (US$0.037/kWh) with a net present value of ≈US$0.42 billion at an 8% discount rate. The framework links Syria’s geothermal rehabilitation pathway with the emerging global natural-hydrogen play concept and identifies where the two can share wells, infrastructure and data. Desktop screening study. No new field measurements; no verified hydrogen discovery is claimed. All targets are literature-based review areas.