This talk will discuss programs in NSF ENG's Division of Chemical, Bioengineering, Environmental, and Transport Systems (CBET) that support fundamental engineering science in the area of solar fuels. Programs in the CBET Division's Process Systems Cluster include the Catalysis and Energy for Sustainability programs. The cluster's programs stress fundamental hypothesis-driven research for novel materials, processes, and/or tools that seek to improve the throughput, resource efficiency or process intensification of chemical conversion processes. Focus in on fundamental understanding emphasizing molecular-level engineering to link to understanding of performance at the process/system level. The talk will include examples of recent grants that support solar fuels that have been awarded by these CBET programs.