Alternative Approach to Determining the Preferred Plant Size of Parabolic Trough CSP Power Plants

Abstract

The share of Concentrated Solar Power plants in power generation has increased significantly in the last decade due to the need to develop and deploy clean technologies that help reduce the carbon footprint of the power generation industry and, at the same time, are less voracious in terms of fossil fuel consumption. As a governmental support to promote the installation of solar plants, different incentives are found in most countries: complementary rates to the market price of electricity (premium), tax credits, financial support, long term power purchase agreements and, in general, other mechanisms that are generally grouped in a “feed-in tariff” that should ideally be more demanding (stringent) over time. The objective of these measures is to make this technology competitive in the mid/long term. At the same time, and in order to distribute these economical resources as fairly as possible, governments have usually limited the power output of those power plants benefitting from these incentives, as a means to prevent oligopolies that would eventually stop technology evolution while concentrating on preserving market conditions. This has led to the common 50 and 80 MW limits that exist in Spain and the USA respectively. As a consequence, OEMs and EPCs have focused on developing reliable and cost-effective CSP plants of these sizes, especially 50 MW. This work is based on unrestrained regulatory or market scenarios, with the aim of finding out which plant size yields the best efficiency at the lowest cost of electricity (COE). In other words, the objective is to establish the plant size of interest for power producers and consumers, should CSP facilities compete in the same market conditions as conventional fossil-fuel plants. The work begins by reviewing briefly the origins of the usual constraints applied to CSP plants. Then, a survey of existing literature dealing with the issue of technical and economic CSP optimization is presented, with a special focus on the work by B. Kelly from Nexant Inc. Taking this work as reference, a model of performance of parabolic trough plants developed in Thermoflex environment to put forth strong project specific feature of CSP facilites. Thermal storage and natural gas hybridization are included among the key design parameters.