This conclusion presents some closing thoughts on the concepts covered in the preceding chapters of this book. The book summarizes the fundamentals of carbon dioxide (CO2), including molecule structure, thermodynamics, and kinetics, explains its chemical stability, which is a direct obstacle for CO2 conversion. It aims to classify various conversion technologies as well as enzymatic, mineralization, photochemical/photoelectrochemical, thermochemical, and electrochemical processes. The book considers electrochemical technologies at both low temperatures and high temperatures. It analyzes economic feasibilities in light of various chemicals/fuels. The book proposes technical and application challenges of CO2 conversion to useful fuels/chemicals. If clean energy sources such as nuclear, solar, wind, geothermal, and so on, are used to run CO2 conversion into useful chemicals/fuels, CO2 emission and energy shortage issues can be relieved along with providing better economic feasibility. The CO2 mineralization system mentioned can be designed to generate electricity and produce industrial valuable products simultaneously, which is economically feasible and environmentally friendly.