SolarPACES

The SolarPACES TCP focusses on concentrating solar thermal technologies, following the vision to achieve a significant contribution of these technologies to the delivery of clean, sustainable energy worldwide. Their specific value for the global future power market comes from the ability to provide dispatchable and firm capacity through storage and hybridization options to act as a balancing supply in power systems with increasing shares of fluctuating renewable energies.
Another important contribution is expected from its potential to provide high temperature process heat for numerous industrial processes, thereby addressing also the very important heat section of the global overall energy demand.
Regarding the power market situation, the operational plant capacity in the current term has increased about five-fold to 5 GW (early 2016) and until 2020 a further doubling is expected from the current project pipeline. Most of these plants include several hours (in terms of nominal production capacity) of storage capacity.
Spain with about 2,3 GW has currently the largest share of concentrating solar power (CSP) plants in its national grid, with monthly shares of up to 4% (yearly 2,4%) in 2015.
Regarding process heat, only a few projects are currently operating, but the recent start of construction of a plant to provide 1,000 MW thermal power (steam) for enhanced oil recovery in Oman can be seen as an example of the future potential.
The main focus of work of SolarPACES TCP lies in the contribution to Technology Evolution and Deployment by promoting the realization of the full range of contributions of concentrating solar technology to global clean energy supply. This ensures global energy security and supports economic development and worldwide engagement especially with young growing economies in the sunbelt countries of the world. This work is organized in six ongoing tasks. Regarding the currently most active power sector, Task I deals with system and Task III with component development aspects. Task II focusses on the development of “solar fuels” production (e. g. hydrogen), Task IV deals with process heat, Task VI specifically with energy services for water supply. Task V analyzes the primary source, (direct) solar radiation.
As one key achievement of this term the progress in development of internationally agreed evaluation and measurement procedures on the way to technical standards in this relatively young technology has to be pointed out.
This is an important support mechanism where an internationally recognized network as SolarPACES TCP has a key role and added value and it contributes strongly to cost degression through common standards and improved bankability. Roadmap development to show the market possibilities and engage industrial and governmental actors for more long term markets like Solar Fuels are another important achievement
At the SolarPACES TCP ExCo level, major efforts have been made to improve the general awareness about the potential of concentrating solar technologies, a communication plan has been developed, the website www.solarpaces.org relaunched and specifically the presence in social networks increased (e.g. linkedin currently >6000 followers). The annual SolarPACES TCP conference with about 600 participants on average during the current term constitutes one of the main efforts of SolarPACES TCP to provide the leading exchange platform for all stakeholders in this sector, including the open access to the conference proceedings to about 200 technical contributions received and reviewed for each conference.
Membership figures are currently constant (20 members), one Sponsor (Mitsubishi) left in 2012, Greece joined as a new member in 2015. At the time of writing membership procedures of Chile, Namibia and Finland are in good progress. 9 members are of Association and Partner countries, thus showing a strong contribution to IEA outreach activities.
Task I:
Solar Thermal Electric Systems Task I addresses the design, testing, demonstration, evaluation, and application of concentrating solar power systems, also known as solar thermal electric systems. This includes parabolic troughs, linear Fresnel collectors, power towers and dish/engine systems.
Through technology development and market barrier removal, the focus of Task I is enabling the entry of CSP systems into the commercial market place.Due to the desire of CSP developers and other stakeholders to promote and increase the financeability of CSP projects, Task I has focused on activities including 1) the development and population of an international project database for commercial CSP systems under operation, construction, or development, 2) the development of acceptance test procedures and standards for CSP systems, 3) the development of best practice guidelines for modeling CSP systems, and 4) the value of CSP in electricity markets with variable energy sources.
Within the 2012-2016 timeframe, Task I completed a final guideline for conducting performance acceptance tests for utility-scale power tower systems [i].The purpose of the guidelines is to provide direction for conducting performance acceptance testing for large power tower solar systems that can yield results of a high level of accuracy consistent with good engineering knowledge and practice. An earlier report provided similar guidelines for parabolic trough systems [ii].
Another current activity aims to specify guidelines for predicting the performance, or energy yield of CSP systems [iii][iv]. Due to the high capacity of solar thermal power plants and large required investment, 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, compare different plant options, optimize technology configuration, investigate the influence of component characteristics, and to assess system performance during commissioning, among other things.
A task-force within the project is nearing completion of a draft handbook focusing on parabolic trough power plants using synthetic oil as heat transfer fluid integrated with a two-tank molten-salt thermal energy storage system. A similar handbook will support yield calculations for molten-salt power tower systems [v].Lastly, Task 1 recently initiated a new activity to evaluate the role and value of CSP electricity in a series of country specific system integration studies.
In 2015, a study was commissioned within the Task to bring together a group of experts from different countries to work closely with experts at Aachen Technical University in Germany. Aachen is implementing a simplified methodology as a first step for estimating the value of CSP electricity generation in a system context in comparison to alternative technologies.The method has been previously applied in a national energy study on the German energy system in 2050.
The team of Aachen Technical University is coordinating the modeling activities of this Task I sub task working group and will manage the collection of the input data. If successfully within this first phase, the model can be expanded to investigate the value of CSP within other SolarPACES TCP member regions.
Task II:
Solar Chemistry Research Task II provides a platform for international cooperation to advance solar-driven thermochemical processes for the production of fuels and materials [1][2], and to demonstrate—at an industrial scale—their technical and economic feasibility.
Most advanced routes for solar production of hydrogen, syngas, and liquid fuels have been demonstrated at pilot scale. Latest examples include solar water splitting using ferrites at 100 kWth power level [3] and subsequent scaling up to 750 kWth at the Plataforma Solar de Almería (PSA); thermal dissociation of ZnO as part of the two-step ZnO/Zn cycle in a 140 kWth solar reactor at the MegaWatt Solar Furnace in Odeillo, France [4]; and steam gasification of low-grade coal and carbonaceous waste in a 150 kWth solar pilot plant at PSA [5]. Recent review articles describe the progress in solar chemical reactor technology for thermal splitting of water [6] and steam reforming of methane [7][8].
At the laboratory scale, a variety of reactor concepts for the solar thermochemical splitting of H2O and CO2 into H2 and CO have been proposed and investigated, such as cavity-receivers with rotating or stationary structures[9],[10], aerosol flow reactors [11], and moving and fluidized bed reactors [12]. Thermochemical conversion of solar energy into chemical fuels offers an efficient path for long- term storage and long-range transport of solar energy. Work is in progress for advanced thermochemical storage systems based on redox cycles for parabolic troughs and central receivers [14].
Novel technologies for solar processing of chemical commodities (e.g., metallurgical Al, Mg, Si, Zn production) are under development. Innovative materials for next generation solar chemical reactors are being developed and qualified.
Worldwide deployment of new solar concentrating research facilities (mainly high-flux solar simulators) is reported. During the current term, Task II has intensified cooperation with other international organizations to leverage technical expertise, benefit from synergism, and avoid duplication of efforts. For example, under the umbrella of the EERA (European Energy Research Alliance) Joint Program on CSP, the Integrated Research Program STAGE-STE (2014-2017) has originated. Thirteen solar research institutes and universities from nine SolarPACES TCP member countries (four of them non- European) join forces to foster research on solar thermochemical fuels and high-temperature materials.
In an attempt to involve industry in developing commercial applications of the most mature solar fuels technologies, Task II has elaborated and published a “Roadmap to Solar Fuels” to facilitate market penetration, initially for Australia and South Africa, later for China and other sun-rich countries [15].
Task III:
Solar Technology and Advanced Applications The main goal of the Task III activities was to provide an international platform for information exchange and cooperation for CSP component development.
The already existing network of scientists and industry was significantly enlarged and intensified mainly due to the EERA (European Energy Research Alliance) activities and the start of a European Joint Programme on CSP, i.e. the project STAGE-STE.
In the framework of EERA, which was restructured during the reporting period, the contributions of the TASK III group were bundled in the subtopic “Materials for CSP”, with a strong link to the individual but also joint activities of a wide number of members of SolarPACES TCP.
In EU-STAGE-STE the work of Task III members focused also on the same topic. This allowed to progress significantly in the field of accelerated ageing of reflectors and performance assessment of components under the view of desert environments [1, 2, 3,4,5,6].
Another focus of the activities was on the development of guidelines for testing. The Task III meetings were held on a yearly basis in form of workshops, counting with 50-70 participants from research and industry. A subgroup developed and disseminated guidelines for reflectance and shape measurement of reflectors [7,8,9]. In this context several partners developed new measurement instruments and agreed on a procedure to verify the quality parameters of reflectors [10-13]. Also, a guideline for optical performance and heat loss measurements for parabolic trough receivers was developed.
A round-robin test of receivers from two manufacturers was performed. Results from evaluation are expected soon. As preliminary results it can be stated that several institutes may provide now test benches and instruments to realize those measurements.
One Task III sub-task working group has started to work also on guidelines for thermal storage and heliostat testing. Another guideline for accelerated ageing of reflectors was finalized and transferred together with the reflectance guideline to the working groups at the relevant Spanish and international technical committees of standardization bodies AENOR CT (Asociación Española de Normalización y Certificación) and IEC-TC117 (International Electrotechnical Commission). [14,15,16]
Task IV:
Solar Heat Integration in Industrial Processes Solar Heat for Industrial Processes is still at the early stages of development, but could contribute strongly to the future heat market. According to the Ecoheatcool study (Ecoheat & Power: The European Heat Market, Final Report of the European Project Ecoheatcool, 2006, http://www.euroheat.org/), around 30% of the total industrial heat demand is required at temperatures below 100°C and 57% of this demand is required at temperatures below 400°C.
To foster the exploitation of this great potential by improved co-operation and knowledge exchange, technology advancements and increased awareness, Task IV was defined as a joint project with the Solar heating and Cooling Technology Collaboration Programme (SHC TCP) Task 49. Based on the results of the previous joint Task (SHC TCP Task 33/ SolarPACES TCP Task IV) and in consideration of the strategic research agenda of the European Solar Thermal Technology Platform the following three subtasks had been defined and were carried out:
– Subtask A: Process heat collector development and testing
– Subtask B: Process integration and process intensification combined with solar process heat
–  Subtask C: Design guidelines, case studies and dissemination
Main Subtask A activities were reviews of collector technologies, their requirements for process heat applications, and appropriate testing standards. Since process heat applications cover a wide range of temperatures and offer different options for solar heat integration at either process or system level, different concentrating and non-concentrating collectors may be considered during the design. They have different characteristics, use diffuse or direct radiation and operate preferably within distinct temperature ranges, but need to be compared and evaluated on an even basis.
The deliverables of this task give a comprehensive overview of the present state of the art, and recommendations for further work required to provide solutions to this challenge.
Subtask B dealt with a systematic approach for the integration of solar heat into industrial or commercial processes with the aim to identify the most technically and economically suitable integration point and the most suitable integration concept.
Due to the complexity of heat supply and distribution in industry, where a large number of processes might require thermal energy, this task is usually not trivial. The key result of this task is a comprehensive Guideline for solar planners, energy consultants and process engineers giving a general procedure to integrate solar heat into industrial processes by identifying and ranking suitable integration points and solar thermal system concepts.
Targets for future research to tackle technical bottlenecks for widespread use of solar energy are
– Adaption of processes to become more efficient and better suitable for solar process heat
– Development of “solar process technologies” based on direct use of solar light and/or heat.
The main objective of Subtask C was to provide technical information and planning methodologies for solar process heat systems to solar manufacturers, process engineers, installers and potential buyers (industry). This shall support the marketing, planning and installation phase of future SHIP plants. A main effort was related to the definition of assessment criteria and performance indicators, for different applications and target groups, and as a basis for future standardization work.
A comparison of different numerical performance simulation tool was carried out, and a public online- database of SHIP plants was initiated (http://ship-plants.info/). It contains a worldwide overview on existing solar thermal plants which provide thermal energy for production processes for different industry sectors.
The SHIP database is designed as a living platform and expected to grow continuously.
Task V:
Solar Resources Assessment and Forecasting 
“Solar Resource Assessment and Forecasting” is a collaborative TCP’s Task under the lead of the SHC TCP. During this period, Task V corresponds to SHC TCP Task 46, which is in force from 2011 up to 2016. It further maintains collaboration with the “Photovoltaic Power Systems” (PVPS) TCP.
The goal of the Task during the reference period was to provide solar energy industry, electricity sector, governments, and renewable energy organizations and institutions with means to understand “bankability” of solar irradiance data sets and develop weather forecasts specialized to the needs of solar energy.
There are 68 task participants from 13 countries collaborating in four different research lines, structured as four Subtasks with the following objectives. Some examples of outcomes are reported in each section.
A. Solar Resource Applications for High Penetration of Solar Technologies: objectives are related to data sets on short-term variability characteristics to support grid integration analysis. Site assessment studies [1], potential assessment [2]or short term variability [3][4] have been studied.
B. Standardization and Integration Procedures for Data Bankability: best practices for data collection and data integration analysis, including typical meteorological years (TMY) formats. 
Example of works are those related to direct normal irradiance (DNI) definitions [5], validation of clear-sky models [6], sensitivity of satellite-derived solar radiation models [7], best practices handbook [8], site adaptation techniques [9][10] or methodologies for probabilistic series generation [11][12][13][14].
C. Solar Irradiance Forecasting: test, development [15][16] and comparison of forecast methods covering different time scales and methodologies [17][18][19] have been topics under international collaborations. D. Advanced Resource Modeling: explore new methodologies as understand climate change and inter-annual variability were under the objectives. Examples of assessment of statistical indicators [20], angular dependence of satellite-derive solar radiation models [21], sky-images-derived solar radiation models [22][23], temporal and spatial variability [24][25][26], modeling the horizontal sunrays pathway [23] or the scattering effect [27] have been carried out.
In addition to the described works, collaborations have been carried out with related international activities. The Task collaborates with the IRENA initiative Global Atlas for Renewable Energy (http://irena.masdar.ac.ae/). IRENA with support from several of the TCP Task Participants aims at closing the gap between nations having access to the necessary datasets, expertise and financial support to evaluate their national renewable energy potential.
Several Task Participants also are involved in the European Programme Copernicus (http://www.copernicus.eu/), previously known as GMES (Global Monitoring for Environment and Security) focusing on solar radiation and aerosol characterization. Several Task Participants are also involved in standardization activities in the context of the International Electrotechnical Committee. Main activity there is the support of IEC TC 117, project 62862-1-2 dealing with creation of annual solar radiation data sets frequently known as TMY for CSP/STE performance simulations. Of general interest for all solar energy applications is the proposal of a flexible time series-format for solar radiation specific meteorological input data, which is drafted as IEC 62862-1-3 and now available as a TCP Report. Also of general interest are the contributions to updated solar radiation instrumentation standards with ASTM and ISO aiming for a revision of ISO 9060.
Task VI:
Solar Energy and Water Processes & Applications Task VI was created to promote and encourage the development of solar technologies simultaneously addressing energy and water issues.
The main goal is the successful creation of a nucleus of interest in the following specific topics of active collaboration:
a) brackish and seawater desalination processes powered by solar energy;
b) integration of desalination processes into CSP plants (CSP+D);
c) solar detoxification processes for the removal of organic compounds, heavy metals and/or hazardous substances from water, and
d) solar disinfection processes, for the control and/or elimination of pathogenic populations from water.
During the reported period a series of new experimental facilities have been implemented in order to demonstrate the technical feasibility of innovative developments for conventional and new desalination technologies allowing assessing their performance under real solar conditions.
At the Plataforma Solar de Almería (Spain) and California (USA) several demonstration projects have been carried out to demonstrate the techno-economic feasibility of the coupling of solar-powered absorption heat pumps to Multiple Effect Distillation (MED) plants reaching the highest thermal performance value for this kind of technology [1].
In France and Germany special emphasis has been put in the development of polymeric heat exchange surfaces for thermal desalination, in order to reduce investment costs and increase competitiveness against membrane processes like reverse osmosis [3][4].
Also during this period, researchers from Germany, Spain, Italy and Mexico have been involved in the assessment of new series of commercial and pre-commercial membrane distillation modules, with their continuous improvement in energy consumption and conversion factor, as well as the extension of their applicability to other fields like brine concentration [5][6].
Task I 
 
Task II 
 
Task III 
 
Task V 
 
 
 
 

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