Sustainability of human beings in the 21st century requires development of renewable energy systems based on technology innovation. Chemical engineering plays a key role in promoting technology innovation relating to environmental and energy systems. The technological domains to which chemical engineering has contributed have shift from petrochemicals to functional materials and devices. An example of the key devices expected in the future is a combination of solar cells and Li-ion batteries, in which the indispensable materials are silicon and carbon. The shape and nanostructure of materials must be controlled to fabricate highly efficient devices at a low cost. Single-walled carbon nanotubes (SWNT) and spherical silicon solar cells (SSSC) with a semi-concentration reflector system are discussed as examples of future materials and devices. Chemical engineering is responsible for technology innovation through mass production, product quality control, materials recycling, high-quality device fabrication, and structuring knowledge.