An analysis of the technical and economic performance of a parabolic trough concentrator for solar industrial process heat application

Abstract

An identification of the principal design factors that influence the technical performance of a parabolic trough concentrator and which relate directly to design and manufacturing decisions is presented. These factors include spectral-directional reflectivity of the mirror system, the mirror-receiver tube intercept factor, the incident angle modifier and absorptivity-transmissivity product of the receiver tube and cover tube, the end loss factor and a factor describing the effect of tracking errors and receiver tube misalignment. Each of these factors has been quantified in terms of design and manufacturing tolerances and associated performance degradation. Other design considerations that relate to thermal loss from the receiver tube are low emissivity coatings, evacuation and anti-reflection coating.The analysis of energy costs using the parabolic trough concentrator is developed. This analysis determines both the break-even, current metered cost of energy and the annual cash flow over periods of investment ranging from 5 to 15 yr. The economic factors include investment tax credit, energy equipment tax credit, income tax bracket, cost of auxiliary system, foundations and controls, cost of collector at installation, costs of maintenance and taxes, costs of fuel, cost of capital, general inflation rate and fuel escalation rate. Economic determinations were made at three U.S. locations: Albuquerque, New Mexico; Fresno, California ; and Caribou, Maine using the thermal performance characteristics of the Sandia Advanced Trough Prototype Collector. The collector costs used were those determined by a manufacturing cost analysis for various manufacturing volumes up to 100 000 modules (each 516 ft2 ; 48 m2) per year.The results show that for a 10 yr period of investment, the current metered breakeven costs are less than $7.00 per 106 BTU at all locations for a collector having a total installed cost of $15.79 ft-2 ($170.00 m-2), which includes manufacturing and installation ($11.50), foundations and controls ($1.50) and auxiliary system ($2.79). For a 15 yr period of investment the corresponding fuel costs are less than $4.00 per 106 BTU at all locations.For a total installed collector cost of $22.79 ft-2 ($245 m-2), the break even metered fuel cost is less than $9.00 per 10[deg] BTU at all locations, also for a 10 yr period of investment. Other conditions are evaluated. The analysis is general which permits other circumstances to be evaluated.