Synthesis of efficient solar thermal power cycles for baseload power supply

Limited fossil fuel reserves and increasing greenhouse gas emissions from fossil fuels make it essential to develop alternative renewable energy conversion processes to meet energy needs. Advancements in renewable power production are especially important since electric power is the largest consumer of primary energy resources with the highest growth rate among alternate energy use sectors, and is currently responsible for greater than 40% of the global CO2 emissions. Among the renewable energy sources, solar energy is prominent due to its abundance. Here, we introduce an efficient solar thermal power cycle, solar water power (SWP) cycle, with water as the working fluid, which undergoes reheats between expansions. SWP cycle is developed to maximize exergy efficiency, allow flexible operation and process intensification. Simulation and optimization of the SWP cycles are performed in an integrated Aspen Plus/MATLAB modeling environment. Modeling results predict that SWP cycle with 1 solar reheating stage has a potential to generate electricity with sun-to-electricity efficiencies greater than 30% at solar heat collection temperature as low as 750 K. The cycle also promises sun-to-electricity efficiencies in the unprecedented range of 40-46% for the corresponding temperatures above 1400 K. Further efficiency increase is estimated by the addition of more reheating stages.