The cost of impurities: A techno-economic assessment on conditioning of captured CO2 to commercial specifications

Abstract

CO₂ capture, utilization, and storage is a key technology to mitigate the climate crisis, and the development of a CO₂ infrastructure is critical for its future large-scale implementation. Successful deployment of a CO₂ infrastructure depends largely on the compatibility between industry links, which is currently limited by unaligned CO₂ purity specifications. Therefore, there is a need to understand the economic and technical implications of purity specifications throughout the whole value chain. This work presents, a highly detailed study encompassing the entire CO₂ conditioning system, including compression, dehydration, liquefaction, and purification. A single, common CO₂ conditioning system derived from operational facilities and designed for post-combustion CO₂ feeds was applied for conditioning of four different feed gases. The investigation includes a techno-economic analysis considering capital and operational expenses for twelve different combinations of CO₂ feed streams and outlet product specifications. The feed sources represent a range of CO₂ purities from high purity to low purity and were derived from post-combustion, pre-combustion, and oxy-fuel combustion processes, while the considered product specifications include CO₂ storage in depleted gas fields, saline aquifer, and utilization in the food industr. For the investigated systems, it is found that low-purity CO₂ was the most expensive source gas to condition to commercial specifications due to a high content of non-condensable gases. The levelized costs for CO₂ conditioning amounted to approximately 25 EUR/t CO₂, 27 EUR/t CO₂, 34 EUR/t CO₂, and 46 EUR/t CO₂ for the investigated high purity, medium-high purity, medium-low purity, and low purity CO₂ cases, respectively. In the investigated cases, only the specifications of low-volatile species were relevant. The impurity limit specifications were relatively close across the investigated commercial specifications, therefore, these did not show significant cost differences. The study clarifies the economic impact on the CO₂ conditioning process from imposing equivalent purity constraints on CO₂ from different sources.