A comparative life cycle assessment for solar integration in CO2 capture utilized in a downstream urea synthesis plant

This study assesses the environmental performance of an existing petrochemical plant that produces urea fertilizer and liquid ammonia. In urea production facilities, ammonia is always in excess. This excess can be converted back to urea if reacted with CO2 in an ammonia reformer. Such a process can boost the production capacity of the plant without the need for further investment in major equipment, like reformers and reactors. In the plant studied here, a CO2 capture and utilization unit (CCU) is used to capture CO2 from the stack of the ammonia plant to further enhance urea production. The unit recovers about 5500 kg of CO2 per hour. The environmental performance of the petrochemical plant is evaluated with and without CO2 capture and under solar-assisted operation. Although the solar-assisted operation performs better than the plant with CCU in many environmental parameters, the differences between the two cases are relatively small. The outcomes of the life cycle assessment show that the carbon footprint of the solar-assisted operation with CCU is about 10% lower than that of the plant without CCU. In addition to some environmental benefits of the CCU plant, the plant with carbon capture increases the urea production by about 8%.