In this study, the chemical exergy of low profile industrial lignite has been studied through a case study at the 1440 MW Afsin-Elbistan B lignite-fired power plant. Chemical exergy methods in the literature were applied to design lignite to investigate results on the exergy efficiency of the power plant for different power rates. The ASTM standard and well known methods have been compared by equating higher heating value (HHV) to chemical exergy. The HHV and chemical exergy of the design lignite were investigated with a previous study to locate the fuel for the plant among the tertiary coals in Turkey. These approaches predicted exergy efficiencies ranging between -2.08% and 4.29% from the average value of the mentioned methods, which showed that there existed an array of exergy efficiencies. The HHV, dry and ash-free chemical exergy and as-received chemical exergy values of Afsin-Elbistan lignite had a very low profile among the tertiary coals in Turkey.