Climate benefits of Power-to-X pathways utilizing green hydrogen – A contradiction of regional and international emission savings

Abstract

Abstract Renewable Power-to-X solutions can provide extensive emission savings by replacing fossil feedstocks directly in the producing country or through exports. This study is based on the hypothesis that different PtX pathways contribute to emission savings in varying amounts. Emission savings from different PtX pathways were quantified by conducting life-cycle assessments using Finland as a case study. Surplus e-products substitute conventional products in Central Europe. The investigated H2 utilisation pathways were e-H2, e-methane, e-methanol, e-fuels, e-ammonia, and green steel. For Finland, grey H2 was always replaced by e-H2. The largest emission savings were achieved when producing green steel (∼17.5 MtCO2-eq). The second largest savings can be achieved when utilising e-H2 for fuel-cell vehicles (∼15 MtCO2-eq), followed by e-ammonia (∼14 MtCO2-eq) and e-methanol (∼11 MtCO2-eq) production. In some cases, production-related emissions exceed the benefits of substitution in Finland if there is insufficient demand for the product, such as in the case of e-ammonia and e-methanol.Production pathways that maximize global emission reductions may differ substantially from those that maximize regional reductions, particularly when domestic demand is low relative to low-carbon production potential. This discrepancy arises because production-based accounting allocates manufacturing emissions to the producing region, even when the resulting low-carbon products deliver emission reductions elsewhere. These contradictions in emission savings may render climate mitigation actions inefficient if only national targets are considered.