Sustainable biogas purification techniques using indigenous materials: a review focused on developing economies

Abstract Environmental degradation and increasing dependence on fossil fuels underscore the urgent need for renewable and sustainable energy alternatives. Biogas is a promising solution, particularly for developing regions, aligning with Sustainable Development Goal 7 (clean and affordable energy). However, the presence of impurities such as carbon dioxide and hydrogen sulfide hampers its efficient utilization. This review aims to evaluate low-cost, locally available purification methods that enhance biogas quality while remaining feasible for small-scale applications. Various adsorbent materials and techniques were analyzed using natural clay, iron-rich soils, steel wool, and compost-based filters. The findings reveal that clay can remove up to 90% of contaminants, iron-rich soils up to 93.8%, steel wool up to 95%, and compost up to 80%. Additional strategies such as drying biomass ash, surface modification of activated carbon, material blending, and adsorbent reuse further improve purification efficiency. These insights demonstrate that sustainable, cost-effective biogas purification methods can significantly boost energy access, reduce fossil fuel dependence, and support environmental sustainability in developing economies.