Thermo-economic Optimization of Hybrid Combined Power Cycles Using Heliostat Field Collector

Abstract

Electricity has an essential role in our daily life. However, with the ever increasing cost of fossil fuels and natural gas, power generation with higher efficiency and lower capital cost is in high demand. Nowadays, global warming and climate change have become vital issues prompting investigations into increasing the share of renewable sources of energy implementation in power generation. Solar energy is arguably the most favorable solution for a greener power generation technology. With solar technology's current level of maturity, solar energy cannot provide a significant contribution to the world's energy demand due to intermittency and storage issues. A possible solution to the aforementioned difficulties is power plant hybridization. In particular, concentrated solar power technologies are displaying significant potential for electricity production. The United Arab Emirates' hot, sunny climate is an indication of the great potential it possesses for hybrid and solar only power plant implementation. In this research work, the feasibility of a 50 MWe hybrid (solar and natural gas) combined cycle power plant with a topping gas turbine cycle and four different bottoming cycles are assessed. Power plant hybridization is accomplished by employing a solar tower collector (Heliostat field collector). Three rather unconventional bottoming cycle configurations have been chosen including gas turbine (air bottoming cycle), water injected gas turbine (humid air bottoming cycle), and the Maisotsenko cycle (Maisotsenko bottoming cycle). These three configurations along with the conventional combined cycle power plant (steam bottoming cycle) are optimized by conducting thermo-economic and transient analyses in MATLAB to identify the most economically justified plant configuration for the United Arab Emirates. Additionally, two different heliostat field layouts are taken into consideration including the radial-staggered and spiral layouts. Moreover, thermo-economic evaluation is accomplished by utilizing five different economic approaches, i.e. net present value, payback period, life cycle saving, Knopf objective function, and levelized cost of electricity.