Professor Jan Szargut was one of the world pioneer of exergy analysis and his adventure with exergy going back to its beginnings in world science. His subsequent and significant contribution to the field of exergy analysis is certainly not to be overestimated. Within the paper a short overview of Professor Szargut activity is presented. One of the important application of exergy analysis proposed by Szargut is the Thermo-Ecological Cost (TEC) let to connect exergy and ecology. The general theory and algorithm of TEC is presented in the paper. The potential results obtained using TEC are presented based on trigeneration system, nuclear power plant and metallurgical process. Finally, the pro-ecological tax is described. (C) 2018 Elsevier Ltd. All rights reserved.