Abstract
The use of fossil fuels should be reduced in near future due to their limited resources and increasing ecological impacts. Therefore, increased interest and incentives have been created for developing electricity supply utilizing renewable energy such as solar energy, which has long-range potential and is applicable in most geographical regions. The objective of this paper is to perform thermodynamic and economic analysis of the proposed integrated solar Derna steam turbine power plant (unit 5) based on the parabolic trough system. Two modes of operation are considered: power boosting mode in which solar energy is used to preheat the feed water in the low and high-pressure preheaters and fuel saving mode in which a fraction of saturated steam is generated by the solar collector field. A simulation mathematical model has been developed for each component of the plant. Also different thermodynamic performance parameters at all points of the plant are considered in the calculations. This study shows that the maximum increasing of overall efficiency of the integrated solar steam power plant (ISSPP) are 5.9% for fuel saving mode and 3.2% for power boosting mode for 21st July at 12:00 with DNI 810 W/m2. During 25 years operating period of solar field, the fuel saving mode saves approximately 121 million $ and reduces about 125,000 ton in fuel consumption and approximately 390,000 ton in CO2 emissions while the augmentations of electrical energy for the power boosting mode are about 360,879 MWh. The study also shows that the paybacks of the solar field cost for the power boosting and fuel saving modes of operation are approximately 15.7 and 11.5 years, respectively.
Highlights
IAPWSElectricity production using solar thermal energy is one of the main research areas at present in the field of renewable energies
This study shows that the maximum increasing of overall efficiency of the integrated solar steam power plant (ISSPP) are 5.9% for fuel saving mode and 3.2% for power boosting mode for 21st July at 12:00 with DNI 810 W/m2
For 21st March, the fuel saving mode results in reduction of fuel consumption and CO2 emission by approximately 8.6% and increasing in overall efficiency by approximately 3.1%, while the power booster mode results in improvement of electrical power by approximately 6% and 1.2% increasing in overall efficiency compared to the conventional steam cycle operating at full load
Summary
IAPWSElectricity production using solar thermal energy is one of the main research areas at present in the field of renewable energies. The SEGS plants apply a two-circuit system, consisting of the collector circuit and the Rankin cycle of the power block. These two-circuits are connected via a heat exchanger. In the case of the Direct Steam Generation (DSG) in the collector field, the two-circuit system turns into a single-circuit system, where the collector field is directly coupled to the power block. This renders a lower investment and higher process temperatures resulting in higher system efficiency. Due to the lower investment and the higher efficiency a reduction of the LEC of 10% is expected when the DSG process is combined with improved components of the solar collectors (Valenzuela et al, 2006)
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