Assessment of solar options for small power systems applications. Volume I. Executive summary

Abstract

Under the sponsorship of the U.S. Department of Energy•s Division of Central Solar Technology, the Pacific Northwest Laboratory performed a comparative analysis of solar thermal conversion concepts that are potentially suitable for development as small electric power systems (1 to 10 MWe). Cogeneration and total electric systems were beyond the scope of this study. Seven generic types of collectors, together with associated subsystems for electric power generation, were considered. The collectors can be classified into three categories: 1) two-axis tracking (with compound-curvature reflecting surfaces), 2) one-axis tracking (with single-curvature reflecting surfaces), and 3) nontracking (with low-concentration reflecting surfaces). All seven collectors were analyzed in conceptual system configurations with Rankine-cycle engines. In addition, two of the collectors (the Point Focus Central Receiver and the Point Focus Distributed Receiver) were analyzed with Brayton-cycle engines, and the latter of the two also was analyzed with Stirling-cycle engines. With these engine options, 10 systems were formulated f or an a 1 ys is. Conceptual designs developed for the 10 systems were based on common assumptions of available technology in the 1990 to 2000 time frame. No attempt was made to perform a detailed optimization of each conceptual design. Rather, designs best suited for a comparative evaluation of the concepts were formulated. Costs were estimated on the basis of identical assumptions, ground rules, methodologies, and unit costs of materials and labor applied uniformly to all of the concepts. The computer code SOLSTEP was used to analyze the thermodynamic performance characteristics and energy costs of the 10 concepts. Year-long simulations were performed using meteorological and insolation data for Barstow, California as input to the code. Results for each concept include levelized energy costs and capacity factors for various combinations of storage capacity and collector field size.

Assessment of generic solar thermal systems for large power applications: analysis of electric power generating costs for systems larger than 10 MWe

“…The primary purpose of this study is to provide DOE with an independent, objective assessment of the principal solar thermal conversion concepts that have the potential for achieving commercial success as large electric power systems (greater than 10 MWe). This evaluation was performed as a follow-on study to an assessment of 1-to 10-MWe solar thermal plants conducted previously for the U.S. Department of Energy (Laity et ale 1979). The results of this assessment will serve as guidance for DOE in making decisions on which concepts warrant priority attention for further technology development .…”

“…Five major engineering ground rules were established at the outset of this study. They were selected to ensure that the results of the study were comparable to those determined by PNL for small solar thermal electric systems in the 1-to 10-MWe range (Laity et al 1979).…”

“…Solar collectors are both the most distinguishing characteristic and most significant cost element of a solar thermal power plant, and are, thus, by far the largest single contributor to levelized energy cost for all concepts analyzed. With the exceptions noted below, collector costs used in this analysis were taken from the previous small power systems analysis (Laity et al 1979(Laity et al , 1980b. These estimates were independently generated at PNL, based upon a comparative analysis of the manufacturing and field installation costs for each collector concept.…”

“…Central receivers, as used in the PFCR/B, PFCR/R, and PFCR/R-Barstow concepts, vary in size as concentrator field size changes. Because of the tremendous size difference between small and large power system configurations, cost estimating relationships developed for the small power systems study (Laity et al 1979(Laity et al , 1980b were no longer valid and had to be reestimated. Cost components for central receivers include the absorber unit and the tower.…”

Assessment of solar options for small power systems applications. Volume V. SOLSTEP: a computer model for solar plant system simulations

“…Such an evaluation was conducted by researchers at the Pacific Northwest Laboratory (PNL) as part of the Small Power Systems Program in the U.S. Department of Energy's Division of Central Solar Technology. The study (Laity et al 1979) aimed to investigate the thermodynamic and economic performance of several proposed designs for solar thermal power plants. This goal required the development of a computer code that could be used to perform a thermodynamic simulation and economic analysis of a plant design under a wide variety of operating conditions.…”