In this project the goal is to find the power of a CO₂ compressor used in a process of storing CO₂ underground. Although the compressor is not 100% efficient and does not exist under ideal conditions, the power can first be calculated as if it were under ideal conditions by calculating its enthalpy and entropy. Residual terms are then added to both the enthalpy and the entropy to account for the behavior of CO₂ under non-ideal conditions. Since the sum of the change in entropy under ideal conditions and the residual terms for entropy is zero, a system of equations with the Redlich-Kwong equation of state can then be set up and solved for the unknown temperature and volume at the desired pressure. Once these are determined, they can be used to find the total change in enthalpy when the compressor is not under ideal conditions. Then, since the molar flow rate of CO₂ is known, the power of the compressor, if it were 100% efficient, can be calculated and divided by its actual efficiency. The power needed to run the CO₂ compressor was found to be 916.92 watts.