Answer Happy

You've read the Rankine Cycle notes now, including the last
section which discusses the flexibility of the heat sources for the
cycle - in particular, the temperature of the heat source doesn't
have to be completely constant for the Rankine Cycle, unlike the
Carnot Cycle.
One somewhat unusual source of heat that is used to drive the
Rankine Cycle is sunlight. Some Rankine cycles operate with organic
fluids, instead of water. The organic fluids tend to have lower
saturation temperatures than water, at the same pressures. This
allows the system to operate and produce power with safer
temperatures and smaller solar collection systems.
Based on what you know about the Second Law of Thermodynamics
and its limits on power cycle efficiency, discuss the implications
of lower saturation temperatures on the maximum efficiency of the
Rankine Cycle.