Work

Direct air capture integration in ammonia plant: A novel process design for advancing decarbonization and green urea productivity

Year: 2026

Type: article

Abstract: This study evaluates the process, thermal-integration, and economic consequences of coupling an alkaline-liquid direct air capture (DAC) system with a natural-gas-based ammonia–urea plant using ASPEN PLUS sensitivity analysis. The revised analysis explicitly separates three integration interfaces: CO₂-depleted air supplied to the ammonia section, atmospheric CO₂ conditioned and compressed for the urea loop, and the additional DAC energy requirement. The air-side results show that DAC causes little change in the furnace and reformer operating trends; where responses are identical or nearly identical, the revised figures report differential metrics rather than redundant overlapping curves. On the urea side, the DAC-integrated configuration gives a urea molar fraction of 0.722 versus 0.720 for the conventional case at a carbamate-condenser temperature of 167.5 °C, while increasing urea-reactor pressure from 140 to 200 kg/sqcm raises the DAC-case urea molar fraction to approximately 0.7425. Importantly, the revised HEN screening shows that the highest explicitly tabulated recoverable process temperature (380 °C) and the urea-loop hot streams (approximately 156–183 °C) can support low- and medium-temperature preheating duties, but cannot directly supply the approximately 900 °C calciner duty of liquid-solvent DAC; a dedicated high-grade heat source or electrified calcination is therefore required. The economic interpretation is also revised. At the stated 50 t/h DAC capture basis and 2.45 MWh/tCO₂ energy intensity, DAC adds 122.5 MWh/h. The unadjusted screening model increases capital cost from $62.27 million to $83.13 million and net annual income from $20.76 million/y to $27.71 million/y; however, under an explicit 8000 h/y screening basis, an energy price above approximately $7.1/MWh eliminates this reported incremental operating-income advantage if no green-urea premium or eligible policy value is available. Retaining the reported three-year incremental-capital recovery requires a combined green-product premium and/or eligible policy value of approximately $49–196/t over an energy-price range of $20–80/MWh, before CO₂ compression, additional O&M, and other integration costs. The proposed route is therefore technically promising for atmospheric-carbon utilization and urea productivity, but its economic and climate advantages are conditional on low-carbon energy, market/policy support, optimized heat integration, and complete life-cycle accounting.

Source: Next Energy

DOI: 10.1016/j.nxener.2026.101104