The examinations of first and second laws of thermodynamics are performed on a 6.5 MW power plant, established in Adana, Turkey. The equipment for the investigated plant can be aligned as a fluidized bed coal combustor (FBCC), a heat recovery steam generator (HRSG), an economizer (ECO), fans, pumps, a cyclone and a chimney. Whole parts of equipment are investigated separately and energetic and exergetic inspections are enforced for whole parts of the plant. The maximum exergy destruction rates in the plant are obtained for the FBCC, HRSG and ECO with 95%, 3% and 1% of the whole system, respectively. Higher excess air in the system induces heat losses, especially in the FBCC component by virtue of the rising in mass flow rate of the flue gas. This situation can be considered as one of the primary reasons of irreversibility. Additionally, higher excess air induces the decrement of combustion efficiency in FBCC. Therefore, this value and adverse effects on combustion efficiency can be decreased by reducing the flow rate of air.