Retrofit designs are compared with building a new amine plant based on SCPUF. In the proposed design, temperature and pressure of key unit operations (e.g., absorber, regenerator) are kept same as those in the base case; and amine circulation rate, reboiler duty and bottom product to feed ratio of regenerator are specified such that values of performance indicators are similar to those in the base case (Section 2.2). Table 5 compares a new amine plant with membrane based retrofit designs. Although there is no methane loss, utility cost of the grass-roots design is 4,462,128 $/year, accounting for 51% of EAOC. This utility cost is over two times of that in both OSMAHRD and TSMAHRD, resulting in a higher SCPUF of 0.577 $/kmol for the new amine plant compared with membrane based retrofit designs (0.421 $/year for OSMAHRD and 0.515 $/year for TSMAHRD).