J. Dersch1*, K. Hennecke1 and V. Quaschning2

1 DLR — German Aerospace Center, Linder Hohe, 51147 Koln, Germany
2 FHTW Berlin, Berlin University of Applied Sciences, Marktstrasse 9, 10317 Berlin, Germany
* Corresponding Author, juergen. dersch@dlr. de

Abstract

Greenius, a software tool for fast calculation of the technical performance and economical figures of merit for different renewable energy systems has been extended to simulate also the usage of concentrating and non-concentrating solar collectors for process heat generation. A case study for a site in southern Spain was made, varying the temperature level of the generated heat. The results show that parabolic trough collectors may provide process heat with similar specific annual yield like CPC collectors at sufficient direct irradiance and at temperatures above 140°C. They offer the potential of much higher annual yields if the can be equipped with vacuum tube receivers, which CPC’s are already using.

The study shows also the flexibility and the broad range of application of the new Greenius version.

Keywords: Renewable energy, Software, Parabolic trough, CPC, Flat plate collector

1. Introduction

The software tool Greenius has been developed at DLR since several years [1] and it is customized to perform fast calculation of the technical performance and economical figures of merit for different renewable energy systems. The calculation is done on an hourly basis for a full year using a typical meteorological data set with this temporal resolution for the specific site of interest.

Technologies already implemented in Greenius are: parabolic trough solar power plants with and without thermal storage, non-concentrating and concentrating PV, dish/stirling systems, wind energy and fuel cells. An additional technology was added now — process heat utilization by non­concentrating and concentrating collectors.

The current version of Greenius offers a great flexibility to define the collector type, the collector orientation, solar field size, storage size etc. Furthermore different load profiles (with hourly resolution for a whole year) may be defined by the user. Heat losses of the field piping are considered as well as cooling down of the whole plant during non-sunshine hours.

Many industries have a large demand for process heat in the range from 60°C to 200°C. At sites with high solar irradiation this demand could be often met by the usage of solar collectors. Due to the high oil and gas prices the usage of solar energy becomes more and more economic and at the same time it reduces the emission of green house gases.

Precondition for an economical usage of solar energy is the knowledge of expected system output and system costs in an early stage of the project. The development of a numerical tool for fast assessment of design and technology options was carried out in the context of the IEA Task 33/IV.

Fig. 1. Sketch of a process heat generating system with parabolic trough collectors

2. Mathematical models