Exergy ratio sources

Exergy Ratios of Primary and Secondary Energy Sources... 

The calculated values of exergy ratios for various primary and secondary sources are shown in Table 1. It 1s to be noted that all the fossil fuel sources are inherently of very high quality. The value of aE greater than unity for coal stems from the fact that a reversible oxidation of carbon at ambient temperature has a negative TQ S and results in production of more work than the enthalpy of combustion, with an associated absorption of heat from the environment. In spite of these high values of < r, when fossil fuels are combusted, say for electrical generation, the maximum temperature is limited not by thermodynamic considerations but by materials constraints. The effective < under this limitation is restricted to values below 0.65. t... 

---