Why is the thermal efficiency of steam power plant low?
The overall coal plant efficiency ranges from 35 % to 48 %. The value varies with the technology, material, parameters (Temp., Pressure) used. At condenser comes the big loophole in plant efficiency. The steam is condensed for reuse. During this process the latent heat of condensation is lost to the cooling water. This is the major loss and is almost 40 % of the energy input.