Cicero, also called "Co-Gen" units if I am not mistaken. Back in the day when I was studying this stuff their was a plant in the State of MA that claimed 59% Thermal Efficiency, a bit off the mark, or is that obtainable? I was under the assumption 60% Thermal Efficiency was obtainable....
Co-gen is when you have a steam host. Combined cycle is the brayton and rankine cycles. The brayton cycle is about 35% effecient and the rankine cycle takes that to around 60% using the waste heat through the HRSG (Heat Recovery Steam Generator).