Abstract
The post-fossil transition challenge for the chemical industry is structural: the industry needs carbon as a raw material, and decarbonization frameworks do not fully address this dependence. Syngas is a central platform intermediate, producible from biomass, wastes, and captured CO2, and the entry point to multiple established conversion routes. Comparing thousands of products across many such routes is difficult to address with detailed methods alone, such as life cycle assessment (LCA) or techno-economic analysis (TEA), which require route-specific data assembled only for a few defined configurations. This study addresses that gap by extending the EcoStrategic Index (ESI) with a pathway-aware approach. Pathway-aware means that products are assessed together with the conversion path needed to reach them, using conversion-depth as a positional structural indicator of downstream processing intensity rather than a direct estimate of cost, energy use, or environmental footprint. The framework introduces a Pathway-Aware Efficiency index (PAE) capturing conversion-depth burden. ESI and PAE represent complementary strategic dimensions: portfolio breadth and value potential versus depth-adjusted pathway efficiency. Applied to eleven syngas-to-chemicals routes covering 2,756 product entries across five value levels, ESI and PAE are computed independently and compared on a dual-index strategic map. The five main-route cases show a complete rank inversion (Spearman’s ρ = − 1.00); methanol sub-routes show a strong negative association (ρ = − 0.829, p = 0.042). No assessed route simultaneously achieves high breadth and high depth efficiency. ESI–PAE supports strategic screening of large pathway portfolios upstream of detailed TEA, LCA, and MCDA assessments.