Evaluating the Potential Benefit of Using Nowcasting Systems to Improve the Yield of Parabolic Trough Power Plants with Single-Phase HTF

Kareem Noureldin,Bijan Nouri,Zeyad Yasser,Tobias Hirsch,Robert Pitz-Paal

doi:10.3390/en14030773

Abstract

Solar field developers include innovative solutions to optimize the energy production of their plants. Simulation tools play a significant role in the design and testing phases as they provide estimations of this yield in different conditions. Transient processes, like passing clouds and solar field start-up, are specifically challenging to optimize and estimate using such simulation tools. Solar fields are subject to high degree of both temporal and spatial variability in the energy input and a detailed estimation can be achieved by simulating subsystems within acceptable time and computational power. Hence, such simulation tools cannot be utilized for tests under realistic operation conditions. The Virtual Solar Field is a computationally efficient simulation tool that allows a detailed transient simulation of parabolic trough solar fields based on single-phase fluids. Using this tool, developers could reproduce a transient test case with exactly the same disturbances to provide fair comparisons between different configurations. In this paper, an evaluation process based on numerical simulations using the Virtual Solar Field is presented. The economic benefit of novel innovative control concepts can be assessed according to the presented scheme. This is demonstrated by evaluating the potential benefit of availability of spatial DNI nowcasts on the control of parabolic trough solar fields. Results show that nowcasting can increase the economic revenue of commercial power plants by up to 2.5% per day. This proves the feasibility of installing such systems.

Highlights

In the solar energy sector, photovoltaic (PV) technologies showed significant reduction in installation and operation costs, that the levelized cost of electricity (LCOE) averaged at less than 50 €/MWh in 2016 with a net globally installed capacity of 300 GW
We focus on line-focusing systems based on solar fields with parabolic troughs and single-phase heat transfer fluid (HTF)
When we reduce the threshold to 100 Wm−2, the loss is significantly reduced to −0.03%; this allows the flow to be too low, such that overheating and extreme temperature gradients can take place when the sky is clear again

Summary

Introduction

In the solar energy sector, photovoltaic (PV) technologies showed significant reduction in installation and operation costs, that the levelized cost of electricity (LCOE) averaged at less than 50 €/MWh in 2016 with a net globally installed capacity of 300 GW. The methods depend mainly on assessing how far the current DNI value is from the expected clear-sky value in the current instant, as well as the duration and amplitude of the disturbance Another source of transient conditions in a solar field is start-up operations as the shadow of the collector loops on one another gradually vanish causing a progressive increase in the energy input to the field [15]. A performance evaluation scheme computes the potential economic income based on an annual average of the LCOE This is compared to the expected revenues resulting from using novel controllers to operate the solar field. It enables the estimation of the economic feasibility of new investments

The Virtual Solar Field and DNI Maps

Solar Resource

DNI Maps and Nowcasting

Solar Field Controllers and Performance Assessment Scheme

Findings

Reference Controller