Modeling Guidelines

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The International working Group will develop, document and
publish guidelines for CSP performance modeling with
international collaboration.

Coordination

Spokesmen:

1st Markus Eck, DLR (markus.eck@dlr.de)

2nd Manuel Blanco, Cener (mblanco@cener.com)

Advisory Board

Task: The advisory board will supervise the project. Its members are representatives from selected industrial partners and from SolarPACES. The nominated members are not active members of any work package. The advisory board will meet if required to check the structure and the progress of the project and to resolve impasses within the project.

Spokesman: Mark Mehos, NREL (Mark.Mehos@nrel.gov)

Members:

Diego Arias, Abengoa
Georg Brakmann, Fichtner
Juan Ignacio Burgaleta, Torresol Energy
Klaus Hennecke, DLR
Mark Mehos, NREL
Mark Schmitz, Flagsol
Eduardo Zarza, Ciemat

Project Description

Due to the high capacity of solar thermal power plants (50 MWel and more) and large required investment, concentrating solar power (CSP) projects are subject to an extensive project development process. Predicting the energy yield of a CSP plant is a crucial task in this process. Mathematical models predicting the system’s energy yield are required to assess single CSP projects (e.g. feasibility or due diligence studies), compare different plant options (e.g. technology, site), optimize technology configuration (e.g. solar field size, storage capacity), investigate the influence of component characteristics (e.g. receiver characteristics), and to assess system performance during commissioning, among other things.

The models used for these tasks differ in complexity and required accuracy, e.g. a model used for project assessment during commissioning should be more rigorous than a model used for a pre-feasibility study. At the moment, numerous modeling approaches exist, and project developers use their own internally-developed system models and assessment methodology. These models often lack validation, and no guideline or benchmark for comparison yet exists for electricity yield analysis of CSP plants. This confusing situation fails to alleviate concerns about technology risk and hinders the acceptance of CSP technology by potential investors. To solve this problem, an international working group within SolarPACES Task I is being initiated to define guidelines for CSP performance modeling.

This process can roughly be divided into the following sub-goals:

Collection, documentation and evaluation of the state-of-the-art modeling approaches and methodologies with international partners
Recommendation for a methodology and modeling approaches for performance modeling considering varying accuracy requirements
Development of a methodology for the validation of system and component models contributing to the yield analysis
International recognition and certification of the methodology (e.g. ASME and/or EN standard)
Accordingly, important milestones include the publication of a CSP performance modeling handbook, and the development of international standards (ASME, EN).

In principal, a methodology for performance modeling of CSP plants describes an appropriate way to calculate electricity production as a function of the actual ambient conditions (DNI, ambient temperature, etc.), considering all relevant system aspects. Accordingly, the electricity yield analysis must not only consider component, sub-system and system performance, but also the operating strategies applied, the transient effects, the uncertainties in input parameters, models and meteorological input data, the selection and definition of appropriate figures of merit, and finally a methodology for validation and benchmarking. To address all these topics appropriately, the structure of the standardization process considers appropriate work packages, an advisory board. Furthermore the project is linked to SolarPACES Task V ‘Solar Resource Knowledge Management’.

WP 1: Coordination Team

Task: The coordination team coordinates the activities of the different work packages. It will arrange regular working group meetings, acquires appropriate funding for the activities and coordinates publications. Furthermore, the coordination team will be the interface to the advisory board.

Expected results:

Preparation of regular newsletters
Preparation of work-shops
Publication of results

1st Spokesman: Markus Eck, DLR (markus.eck@dlr.de)

2nd Spokesman: Manuel Blanco, Cener (mblanco@cener.com)

Members:

Tobias Hirsch, DLR
Clifford Ho, Sandia
Juan Ignacio Burgaleta, Torresol Energy

WP 2: Structural Framework

Task: This work package is the core work package, since an overall structural framework and a methodology for CSP yield analysis will be defined, that guarantees the consideration of all conceivable CSP systems and aspects affecting the electricity yield of CSP plants. Furthermore, a structuring methodology will be defined for sub-dividing CSP systems in appropriate sub-systems with clear interfaces. Finally a unique nomenclature for parameters, effects and figures of merit will be defined.

Expected results:

Definition of application areas (quality levels)
Division into modeling units called sub-systems
Preparation of documentation guidelines
Maintenance of nomenclature
Close communication with other work packages

WP-Leader: Tobias Hirsch, DLR (tobias.hirsch@dlr.de)

Participants: Cener, Ciemat, DLR, NREL, Sandia

WP 3: Component Modeling

Task: Within this work package, the modeling approaches available for the different CSP systems and sub-systems will be collected and assessed. The work in the sub work packages will be coordinated to guarantee consistency. The final models recommended for yield analysis will necessarily comply with the guidelines regarding interfaces and structure defined in work package 2. Due to the wide range of conceivable CSP systems, this work package is sub-divided in separate sub-work-packages for each CSP technology such as parabolic troughs, linear Fresnel-Collectors, solar towers and parabolic dishes, along with power plants and storage systems. Furthermore, a data book will be edited summarizing default values and uncertainties for all model parameters used

Expected results:

Collection of available modeling approaches
Assessment and recommendation of modeling approaches for relevant components

WP-Leader: Jürgen Dersch, DLR (acting) (juergen.dersch@dlr.de)

Subtasks:

WP 3.1 Parabolic Troughs / Linear Fresnel (Link to WP 3.1)
WP 3.2 Solar Tower (Link to WP 3.2)
WP 3.3 Storage System (Link to WP 3.3)
WP 3.4 Dish Systems (Link to WP 3.4)
WP 3.5 Power Block (Link to WP 3.5)

WP 3.1: Trough/Linear Fresnel

Task: Within this work package, the modeling approaches available for line-focusing systems will be collected and assessed. The final models recommended for yield analysis will necessarily comply with the guidelines regarding interfaces and structure defined in work package 2. Furthermore, default values and uncertainties for all model parameters used will be collected.

Expected results:

Collection of modeling approaches available for troughs and linear Fresnel collectors
Assessment and recommendation of modeling approaches for troughs and linear Fresnel collectors

WP-Leader: Jürgen Dersch (acting) (juergen.dersch@dlr.de)

Participants: Abengoa Solar, Ciemat, DLR, FhG-ISE, Flabeg, Flagsol, Novatec-Biosol, NREL, SkyFuel, Torresol Energy

WP 3.2: Solar Tower

Task: Within this work package, the modeling approaches available for solar tower systems (including heliostats, heliostat fields and receivers) will be collected and assessed. The final models recommended for yield analysis will necessarily comply with the guidelines regarding interfaces and structure defined in work package 2. Furthermore, default values and uncertainties for all model parameters used will be collected.

Expected results:

Collection of modeling approaches available for solar towers
Assessment and recommendation of modeling approaches for solar towers

WP-Leader: Michael Wagner, NREL (michael.wagner@nrel.gov)

Participants: Abengoa Solar, Cener, CSIRO, DLR, NREL, Sandia, Torresol Energy

WP 3.3: Storage Systems

Task: Within this work package, the modeling approaches available for thermal energy storage systems will be collected and assessed. The final models recommended for yield analysis will necessarily comply with the guidelines regarding interfaces and structure defined in work package 2. Furthermore, default values and uncertainties for all model parameters used will be collected.

Expected results:

Collection of modeling approaches available for thermal storage systems
Assessment and recommendation of modeling approaches for thermal storage systems

WP-Leader: NN

Participants: Abengoa Solar, Arizona State University, DLR, Flagsol, NREL, Purdue University, Sandia, Torresol Energy

WP 3.4: Dish Systems

Task: Within this work package, the modeling approaches available for dish systems will be collected and assessed. The final models recommended for yield analysis will necessarily comply with the guidelines regarding interfaces and structure defined in work package 2. Furthermore, values and uncertainties for all model parameters used will be collected.

Expected results:

Collection of modeling approaches available for dish systems
Assessment and recommendation of modeling approaches for dish systems

WP-Leader: Manuel Silva, University Seville (silva@esi.us.es)

Participants: DLR, Sandia, University Seville

WP 3.5: Power Block

Task: Within this work package, the modeling approaches available for power blocks applicable for CSP systems will be collected and assessed. Power blocks considered will be Clausis-Rankine, Joule-Brayton and combined cycle processes. The final models recommended for yield analysis will necessarily comply with the guidelines regarding interfaces and structure defined in work package 2. Furthermore, values and uncertainties for all model parameters used will be collected.

Expected results:

Collection of modeling approaches available for power blocks
Assessment and recommendation of modeling approaches for power blocks

WP-Leader: Jürgen Dersch, DLR (juergen.dersch@dlr.de)

Participants: Abengoa Solar, Cener, DLR, NREL, Politecnico di Milano, Torresol Energy

WP 4: Operation Strategies

Task: If thermal storage or fossil back-up systems are used in CSP plants, a number of different operation strategies are conceivable. E.g. the operation strategy may aim for a 24 h operation or maximizing gains at the electricity stock exchange. Each operation strategy will lead to different yields and accordingly, they have to be considered appropriately. In this work-package relevant operation strategies will be identified and described in compliance with work-package 2.

Expected results:

Collection and mathematical description of relevant operation strategies
Definition of a methodology to consider operation strategies

WP-Leader: Philipp Stukenbrock, Pöyry (philipp.stukenbrock@poyry.com)

Participants: Abengoa Solar, Ciemat, DLR, Flagsol, Infinia Corp, NREL, Politecnico di Milano, Purdue University, Torresol Energy

WP 5: Transient Effects

Task: Transient effects such as start-up and shut-down sequences or cloud passages can significantly affect the electricity yield. In a first step the relevant transient effects will be identified and a methodology for the correct consideration of these effects will be defined. Depending on the quality requirements of the yield analysis these transient effects may be considered by correction parameters or functions. Definition of thermal masses to consider inertia or correct physical modeling is also conceivable for high quality analyses. Again, the approaches developed have to be in compliance with the overall framework derived in work-package 2.

Expected results:

Collection of relevant transient effects
Estimation of effect of transients on plant performance
Definition of a methodology to consider transient effects

WP-Leader: 1st P. Garcia, Cener (pgarcia@cener.com)

2nd Tobias Hirsch, DLR (tobias.hirsch@dlr.de)

Participants: Cener, Ciemat, DLR, Flagsol, Purdue University, Sandia, Torresol Energy,

WP 6: Uncertainties

Task: The models used for yield analysis are subject to uncertainties in features, events, and processes that are reflected in the uncertainty of the model input parameters. These uncertainties affect the calculated electricity yield directly. Since investors desire to have information on the confidence interval of predicted electricity yields, the effect of the uncertainties has to be quantified. In this work package, a common methodology for the consideration of relevant uncertainties and the derivation of confidence intervals will be defined. Finally, the data book edited in work-package 3 will be extended by default values for uncertainties in model parameters.

Expected results:

Collection of potential methodologies to consider uncertainties
Identification of relevant uncertainties
Definition of a methodology to consider uncertainties

WP-Leader: Clifford Ho, Sandia (ckho@sandia.gov)

Participants: Ciemat, DLR, Purdue University, Sandia, Suntrace GmbH,

WP 7: Key Financial Criteria

Task: Usually, a CSP project will be assessed by the levelized costs of electricity (LCOE) at a given site. The calculation of the LCOE depends on the financial model used and the financial parameters assumed. To reach comparability of different calculated LCOE, general guidelines for financial modeling and parameterization have to be defined. Furthermore, it has to be assessed whether the LCOE is the appropriate figure of merit in all cases or if additional figures of merit should be considered.

Expected results:

Collection of potential financial assessment criteria
Collection of default values for plant and O&M costs
Recommendation of key financial assessment criteria

WP-Leader: Boris Westphal, Suntrace GmbH (boris.westphal@suntrace.de)

Participants: NREL, PWC, Torresol Energy, Suntrace GmbH, Worldbank

WP 8: Meteorological Input

Task: The performance of a CSP plant depends strongly on the meteorological boundary conditions of the given site such as direct normal irradiance, ambient temperature and relative humidity. Task V of SolarPACES is already aiming at the standardization and benchmarking of solar resource data. Accordingly, work-package 8 is intended as an interface between the ongoing task V activity and the yield analysis activity. In this sense it is guaranteed that the specific needs of yield analysis will be considered within task V.

Expected results:

Definition of requirements for meteorological input data
Consideration of these recommendations within Task V

WP-Leader: Richard Meyer, Suntrace GmbH (richard.meyer@suntrace.de)

Participants: Cener, Ciemat, CSP Services, DLR, Solar-Millennium, Suntrace GmbH

WP 9: Validation Methods

Task: So far, standard procedures for the validation of yield analysis methods or programs do not exist. Furthermore, it is not even clarified whether a validation on hourly, daily or yearly basis is required. This work-package has to define a validation procedure, validation figures of merit and an appropriate duration of the validation period. Defining a reference benchmark for latter yield analysis programs is another task of this work package. Since a rigorous validation of the proposed methodology and modeling approach will increase the reliability of CSP yield analysis and the confidence of potential investors, this is a crucial work-package.

Expected results:

Definition of a methodology for performance model validation
Definition of a standard validation data set
WP-Leader: N.N.

Participants: Cener, DLR, FhG-ISE, NREL, Politecnico di Milano, Sandia

WP 9.1: Data Acquisition

Task: The aim of this work package is the search preparation and documentation of high quality performance data of real CSP plants for bench marking and model validation.

Expected results:

Provision and documentation of measured operation data

WP-Leader: N.N.

Participants: Abengoa Solar, Sandia

WP 9.2: Model Benchmarking

Task: A benchmark of available performance prediction models is performed to identify differences in modeling approaches and to investigate the influence of the different effects considered.

Expected results:

A detailed side-by-side comparison of electricity output predictions by several different models given the same input boundary conditions
Electricity predictions will be compared at every time step given a variety of weather conditions (e.g. clear sky and partly cloudy conditions)
Modeling assumptions that cause different predictions will be identified

WP-Leader: Greg Kolb, Sandia (gjkolb@sandia.gov)

Participants: ANU, Cener, Ciemat, DLR, FhG-ISE, Sandia, Flabeg, Flagsol, NREL, Politecnico di Milano, Sandia

WP 10: Communication Infrastructure

Task: The findings of all work-packages will be edited in a joint hand book for a standardized methodology for CSP yield analysis. In a first step it will be decided if a web-based approach or a printed version will be the preferred publishing mode. Independent of the final publishing mode, for day to day work of the standardization team a Wiki system will be implemented to allow for an efficient way of knowledge exchange and collection. This work package covers the operation of the Wiki system only. The technical contributions to the hand book will be compiled in the specific work packages.

Expected results:

Implementation and operation of a Wiki system
Edition of the hand book

WP-Leader: Nils Ahlbrink, DLR (nils.ahlbrink@dlr.de)

Participants: DLR, NREL, Suntrace GmbH

Sponsoring:

We are permanently looking for an appropriate funding of this project. If you want to support the project you can contact Markus Eck (markus.eck@dlr.de)

So far, the project is supported by:

SolarPACES ExCo

Frequently asked Questions

Who will benefit from STAMP?

Investors:

Improved confidence in technology due to transparent performance prediction
Comparability of different projects will be improved
Reduction of overall costs due to reduced risk surcharges

Project Developers:

Make use of best method available for performance prediction without laborious model development
Speed up development and marketing of projects
Reliable assessment of different technological approaches with same methodology

EPC contractors: