Solar power generation system

A solar power generation system comprising:

• a thermal energy storage vessel defining an internal space containing a thermal mass composition operable to store thermal energy;
• a solar energy collection system comprising a first closed flow loop including a solar collector configured to absorb solar energy and heat a first working fluid, the first closed flow loop configured to circulate the heated first working fluid through and heat the thermal mass composition in the thermal energy storage vessel;
• a power generation system comprising a second closed flow loop including a turbine, the second closed flow loop configured to circulate a second working fluid through the thermal energy storage vessel to absorb thermal energy from the thermal mass composition and heat the second working fluid for introduction to the turbine;
• an electric generator operably coupled to the turbine to produce electricity;
• wherein the solar collector is a concentrated solar power unit comprising a plurality of heliostats each comprising a reflector and a centrally-located power tower comprising a plurality of thermal receivers which form a fluidic part of the first closed flow loop, the reflectors being operable to direct sunlight onto the thermal receivers to heat the first working fluid which flows through the thermal receivers;
• further comprising a preheater configured to preheat the first working fluid in a cooled condition returned to the solar collector from the thermal energy storage vessel using an extracted portion of the heated first working fluid leaving the solar collector which is drawn from the first closed flow loop;
• wherein the preheater is fluidly coupled to a bypass piping loop configured to flow the extracted portion of the heated first working fluid through the preheater and heat the cooled first working fluid flowing through but fluidly isolated from the extracted portion;
• wherein the preheater is a shell and tube heat exchanger, the heated first working fluid flowing on a shell-side of the heat exchanger and the cooled first working fluid flowing through tube-sides of a plurality of heat exchange tubes extending through the preheater.