Investigation of low enthalpy geothermal resources in the transitional geological environment: a pathway to Nigeria's Sustainable Development Goals achievement.

内容摘要

Nigeria faces a significant energy deficit (61.2% electricity access), hindering progress toward SDG 7 (Affordable and Clean Energy) and SDG 13 (Climate Action). Despite geothermal potential, comprehensive assessments of low-enthalpy resources (that is, subsurface temperatures below 100 &#x2103;) in transitional geological environments (TGEs) - basement-sedimentary contact zones with mixed conductive-advective heat transfer - remain underexplored. This study uses high-resolution aeromagnetic data interpretation with statistical modeling to delineate geothermal potential within the Egbako-Share axis of North-Central, Nigeria. Spectral analysis adopting centroid depth technique from 40 overlapping blocks was employed to estimate Curie Point Depths (CPD), geothermal gradients (GTG), and heat flow (HF). Statistical modeling - including correlation analysis, multiple regression, PCA, and spatial autocorrelation (Moran's I, Getis-Ord Gi*) - provided a robust framework for resource assessment and risk evaluation. The analysis revealed significant geothermal resources with CPD ranging from 26 to 46&#xa0;km (mean: 38&#x2009;&#xb1;&#x2009;6&#xa0;km), GTG of 13-23&#xa0;&#xb0;C/km (mean: 16&#x2009;&#xb1;&#x2009;2&#xa0;&#xb0;C/km), and HF values of 31-57 mW/m&#xb2; (mean: 39&#x2009;&#xb1;&#x2009;6 mW/m&#xb2;). Strong negative correlations between CPD and both GTG (r = -0.892, p&#x2009;<&#x2009;0.001) and HF (r = -0.891, p&#x2009;<&#x2009;0.001) were established, with the regression model explaining 79.5% of HF variance. PCA identified 12 high-potential geothermal zones for low-enthalpy development. Under a conceptual scenario assuming full development of all 12 zones, modelled capacity could range from approximately 15 to 25&#xa0;MW, with scenario-based annual CO2 emission reductions of 85,000-140,000 t/year (subject to confirmatory drilling and feasibility studies), supporting Nigeria's SDG 7, SDG 13, and related development targets.