Prof. Cao has made major contributions to clean energy and safety engineering research and practice. He is the pioneer to establish the integrated geology and engineering as a solution system to enhance energy production while eliminating safety risks and carbon emissions. He is the innovator and published the first paper on CO2-fracking that launched this field of research for sustainable energy development. He has established companies to transfer his research to field application that demonstrated his leadership in engineering innovation. He has played active roles in promoting engineering education and research to the public, to communities and throughout his profession