Energy, exergy and exergoenvironmental (3E) analyses of power plant integrated with heliostats solar field

Abstract

This paper analyzes a solar tower power plant driven by a heliostat solar field, which has no fuel consumption. Exergy and exergoenvironmental assessments are utilized to evaluate the sustainability of power, based on the Eco-Indicator 99 method. This solar system does not burn fuel, and therefore there is no generation of greenhouse gases (GHG) due to combustion. The direct normal irradiance per hour was considered to evaluate the performance of the plant. The results indicate that the heliostat field and solar receptor present the highest exergy destruction rates and are responsible for the highest environmental burden of plant. The worst components from an exergoenvironmental perspective were identified. The best case of the solar tower power plant considers a daily operation of 12 h. This condition produced the lowest specific environmental impact of electricity (0.543 mPt/kWh) and the highest exergy efficiency, 18.89%. However, this condition led to the highest environmental impact rate for components, 55.99 Pt/h, due to the net power of 104.69 MW. When the system operates for 24 h per day, the specific environmental impact of electricity is 0.95 mPt/kWh. The results are compared with the literature data. The effect of the energy storage system reduced the net power and increased the amount of molten salts. The environmental impact rate associated with components and total environmental impact rate have a dominant effect on the environmental performance of the plant. A sensitivity analysis showed the effect of operation time, which reduces exergy efficiency and increases the specific environmental impact of electricity.