solar ponds, etc. The low temperature heat is converted into useful work, that can itself be converted into electricity.
Organic Rankine Cycles seem to be a promising technology in the perspective of a decrease in plant size and
investment costs. They can work at lower temperatures, and the total installed power can be reduced down to the kW
scale. The market for ORC's is growing at a rapid pace. At the present, Organic Rankine Cycle (ORC) raises
considerable interest as it makes it possible to produce electricity from cooler geothermal sources, typically within
the 100–130 °C temperature range, exceptionally down to 90–95 °C, often available from below 1000 m deep
production well increasing the number of geothermal reservoirs in the world that can potentially be used for
generating electricity. Among the literature studies concerning this topic, Franco [1] presented an overview of
current R&D in the field of small-scale ORC for the exploitation of geothermal sources with reduced temperature
below 130 °C. He analyzed the performance of such those new cycles and to consider the potential improvements
that will result in higher cycle performance or lower resource utilization and lower cost of electricity generation. He
showed that the geothermal power plant with a regenerative Organic Rankine Cycle is an interesting and promising
option, in particular the benefit gained by adding a regenerative heat exchanger which provides some of the
preheating heat from the vapor exiting the turbine. Ghasemi et al. [2] provided numerical models for an existing
commercial ORC operating by a regenerative cycle and using isobutane as working fluid. The condensation system
was of air-cooled type. From their simulation results, validated by comparison with experimental data, it appears that
at high ambient temperatures, the net power output of the ORC is limited by the capacity of condenser system. They
also observed that at low ambient temperatures, the inlet of turbine should be in a saturated vapor state and the
maximum feasible pressure as suggested by previous studies. However, as the ambient temperature increases, this
conclusion does not hold anymore and a significant superheat is required to obtain the maximum in net power output
of the ORC