The productivity of cell-free protein synthesis depends critically upon the efficiency of ATP regeneration. In addition, the expensive energy sources used in the conventional cell-free protein synthesis systems account for the major part of the overall cost for the expression of proteins. Therefore, it is essential to implement a cheaper and more efficient ATP regeneration method in order to make cell-free protein synthesis a viable option for industrial protein production. In this article, we review the recent progress in the methodologies for supplying ATP during cell-free protein synthesis in E. coli extracts.