Techno-economic evaluation and carbon balance of multiple process routes for light olefin production from green hydrogen and captured CO₂

This work benchmarks six plant-scale process configurations for converting captured carbon dioxide and renewable hydrogen into light olefins on a consistent modeling, costing, and cradle-to-gate carbon-accounting basis, spanning different combinations of reverse water–gas shift, carbon-oxide hydrogenation, methanol dehydration, direct dimethyl ether synthesis, and methanol-to-olefins conversion. A steady-state model representing an industrial unit with heat integration and recycle loops quantifies energy efficiency, single-pass selectivity, capital and operating expenditure, and cradle-to-gate carbon balance. The configuration that first hydrogenates carbon dioxide to methanol and then transforms the oxygenate stream in a methanol-to-olefins reactor requires the fewest reaction and separation stages and delivers the lowest levelized production cost, 3.71 USD per kilogram of olefins, at a reference capacity of 100 kt/y. All schemes remain carbon-negative, sequestering on average 2.15 kg of CO₂ per kilogram of product. Scaling studies indicate that increasing plant size yields substantial cost reductions up to roughly one million tonnes per year, after which benefits plateau. The results position CO₂-derived olefins as a viable complement to petroleum-based routes while highlighting the need for advances in catalyst durability, process intensification, and low-energy CO₂ capture to improve commercial competitiveness.