Comparative efficiency analysis of green hydrogen production with the process of direct air capture (DAC) and desalination in West Africa: A case study of M’bour, Senegal

Abstract

In the transition towards a sustainable energy system with low-carbon emissions, green hydrogen production is emerging as a key pathway to reduce dependency on fossil fuels. In West Africa, the abundance of renewable energy sources offers significant opportunities for this transition. However, water scarcity remains a critical challenge. This study compares the efficiency of two water supply processes for green hydrogen production: desalination via reverse osmosis (RO) and direct air capture (DAC) via the solid direct air capture (S-DAC) method, both powered by a hybrid system of solar PV and wind energy coupled with proton-exchange membrane electrolysis (PEM). Using a techno-economic assessment combined with cost efficiency accounting method, with the cost efficiency (CE) as an indicator. The CE is the ratio of ideal and actual costs of production. The analyses evaluate the performance of the two processes under ideal conditions (No losses ) and actual conditions (with losses) by using the CE with M’bour, Senegal, as a case study. The levelized cost of hydrogen (LCOH) represents the ideal and actual costs of production, respectively, in the ideal and actual cases. The results show that desalination-based green hydrogen production from seawater desalination is more cost-effective than DAC-based hydrogen production. Under actual conditions, the levelized cost of hydrogen (LCOH) from desalination was 5.304 €/kg compared to 6.209 €/kg for DAC, while both processes yielded nearly identical costs of 3.83 €/kg under ideal conditions. The cost efficiency (CE) analysis of the two methods demonstrates that desalination achieves 72% compared to DAC, with 62%, reflecting lower value losses for desalination-based hydrogen production and a better alignment between theoretical and practical performance. Sensitivity analysis confirmed that the hybrid renewable configuration is the best option in a region where solar and wind are abundant, while production based on wind energy increases the value losses, particularly for DAC. The findings of this analysis suggest that in coastal areas, specially M’bour, where seawater is available, desalination should be prioritized for the production of green hydrogen. Nevertheless, S-DAC is a strategic potential for inland and arid regions.