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High flux solar facilities for Europe

Final Report Summary - SOLFACE (High Flux SOLar FACilities for Europe)

In the frame of the Sixth Framework Programme (FP6) 'Integrating Activities -Transnational Access' of the European Commission, SOLFACE proposed to public or industrial European scientists to access, free of any charge, the PROMES-CNRS's high flux solar facilities at Font-Romeu - Odeillo, France to:
the MegaWatt solar furnace (MWSF);
- and the 11 medium size solar furnaces (MSSFs);
their associated experimental devices, their related diagnostic instruments, and high level materials characterisation techniques. Each year, users proposals were examined by the international users selection panel (USP), and the selected projects gained access to the facilities.

SOLFACE, hosted by PROMES-CNRS, offers to perform high quality research in two of the seven FP6 Priority Thematic Areas:
- Area 3: Nano-technologies and nano-sciences, knowledge-based functional materials, new production process and devices. This area addressed: the understanding of the basic phenomena and the mastering of the elaboration processes of nano-structured materials (fullerenes, C-nanotubes, ceramics), the synthesis of knowledge-based high value added material and the fundamental behaviour of multifunctional materials under extreme conditions.
Area 6: Sustainable development, global change and ecosystems. Research is related to: the solar production of benign chemical energy carriers, cycles for chemical storage of solar energy and the capture and the sequestration of CO2.

New highly promising and original research domains, some of them unexplored, were studied at the laboratory, creating a unique top level working atmosphere. Among them:
- fundamental studies of the solar photo-excitation and the solar photo-luminescence of gaseous species for the accurate analysis (temperature, composition) of the gas phase at the interface with the condensed phase during high temperature solar processes;
- solar synthesis methods for the production of nano-structured materials, from the understanding of the elementary growing mechanisms to the identification and the mastering of the main parameters for the up-scale production;
- simulation of the extreme conditions occurring during high temperature processes and spatial applications for the study of the physico-chemical behaviour and of the thermo-physical properties of materials.

SOLFACE facilities of PROMES-CNRS at Odeillo offered a whole range of high and very high flux solar furnaces. They were associated with a large variety of modular reactors and equipments at focus, designed and developed at the institute, to perform in the best conditions high level research in a very large scientific domain. The facilities were perfectly suited to support high-risk - high-gain fundamental research as well as more established mature research at an industrial pilot scale.

The MWSF is the more powerful solar furnace in the world: power up to 1 MW, peak heat flux around 10 000 kW/m2 at focus, peak temperature above 3 000 K.

Several modular experimental apparatus were available at focus, particularly:
- Mediase, a chamber permitting high temperature heating under secondary vacuum or controlled atmosphere, additional ion and / or UV irradiation, material thermophysical characterisation: qualitative and quantitative mass loss, directional spectral or total thermoradiative properties;
Mecarbsol, a pilot reactor for the synthesis of carbon complex molecules (fullerenes) and carbon nano-structured materials (nanotubes) under controlled atmosphere.

The MSSFs was a set of 12 medium size solar furnaces from 1 to 50 kW:
- one 50 kW solar dish (SDISH 50 kW), offering a peak flux of 6 000 suns;
- one mid-scale solar facility (MSSF) which had been operated for more than 30 years: power 6 kW, peak flux 5 000 suns, including a shutter to finely modulate the concentrated solar power;
- ten mid-scale facilities (MSSFs), which had been operated for more than 40 years: power 1 or 2 kW, peak flux 16 000 suns, allowing temperatures largely beyond 3 500 K. Two of this furnaces are with a horizontal axis, the eight remaining being vertical axed. Most of these furnaces are equipped with shutters to easily modulate the power as needed.

The irradiation of several facilities was monitored with shutters or flux regulators, among them the 'Sesame' with carbon composite blades which allowed full modulation of the power as fast as one fifth of second, and the shutter at the 6 kW MSSF with speed down to two third of second.

SOLFACE's MWSF and MSSFs were associated to:
-high quality online and offline diagnostics: optical or fibre optic pyrometry, fiber optic pyroreflectometry, radiometry and spectro-radiometry, infrared spectrometry, infrared camera, mass spectrometry, optical spectroscopy, IR gas analysis, IRTF gas chromatography, OES, ICP-MS;
- high precision fast calorimeters suited to the wide possible range of the furnaces operating conditions, optical flux measurement based on real-time image analysis;
- advanced materials analysis and characterization techniques: SEM, XPS, AES, ELS, XRD, EPMA (EDS, WDS);
- quality data acquisition systems for the common signals and automatic control systems for simple processes;
- actinometric and weather station with a fine continuous archiving of all the data, notably up to 1 Hz for the recorded solar parameters - direct normal, global and diffuse irradiations.

SOLFACE offered access to a unique and original combination of:
- numerous high flux solar concentrators and coupled modular reactors;
- concentrated power range from 1 kW to 1 MW;
- associated diagnostics and materials characterisation techniques;
- scientific skills;
- high quality sunny climate.

The world-class quality of SOLFACE was that no other laboratory in the world allowed to benefit from the whole of these assets. There was an annual selection procedure in order to access SOLFACE. At first the candidates had to fill the user proposal form (UPF), which composed of three parts: the first one to identify clearly the candidate, the second one to describe the scientific activity and experience, the third one to expose accurately the work to realize during the access to SOLFACE and the requested facility to access.

In the second step, each proposal was evaluated technically by the SOLFACE technical panel (STP) leaded by the scientist responsible of the concerned research area at PROMES. The STP was divided into four activity domains:
- solar fuels and solar energy storage (leader: Dr Stéphane Abanades)
- solar photo-excitation, photon-matter interaction (leader: Dr Bernard Granier)
- behaviour of materials under extreme conditions (leader: Dr Marianne Balat-Pichelin)
- nano-structured materials and others (leader: Dr Claude Monty).
This evaluation was based exclusively on the technical possibilities of SOLFACE to address the proposal.

In the third step, the proposals were submitted, joined with their STP evaluation, to the users selection panel (USP), which composed of five international high grade international experts. The selection was established on the basis of the scientific merit of the proposals, without any restriction of scientific domain, with a special care to give access to research areas which are outside the present fields of interest of PROMES-CNRS.

The effective access provided during the four years was definitely much higher compared to the terms of the contract. SOLFACE was expected to receive a minimum of 24 projects and 48 users for the four years. Thanks to a good financial management of the contract and the great scientifically interest expressed by the European users, there was an opportunity to host supplementary projects during the four years.

In summary, the program had a really great success, with 30 % more projects and 70 % more users than targeted. The balance for the period of the contract was:
- 32 research projects were hosted;
- 83 scientists (users) from 10 European countries took part in the program;
- more than 60 scientific articles and international communications were published.

SOLFACE contributed to the creation of the European Research Area (ERA) by the following actions:
- opening the facilities to scientists from Europe and extended Europe to improve the scientific cooperation between researchers;
- improving the development of scientific critical mass in domains where the knowledge was widely dispersed;
- generating strong projects at the European scale to increase their competitiveness and open new research horizons.

SOLFACE also contributed to strengthen knowledge in more or less unexplored scientific domains by allowing innovative work from new users with the concentrated solar clean energy such as the solar pumped laser technology or high performance coatings to increase material lifetime.