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From 1984 to 1992, the first commercial solar thermal power plants — SEGS I to IX — were built in the Californian Mojave desert. The first generation of trough collectors (LS1) used in SEGS I showed an aperture area of about 120 m2 (1’292 ft2), having an aperture width of 2.5 m (8.2 ft). With the second generation collector (LS2), used in SEGS II to VI, the aperture width was doubled to 5 m (16.4 ft). The third generation (LS3) has been increased regarding width (5.76 m or 18.9 ft) and length (96 m or 315 ft) to about 550 m2 (5’920 ft2) aperture. It was used in the last SEGS plants VIII and IX, those plants having a capacity of 80 MW each. After more than 10 years stagnancy, several commercial plants in the US (the 64 MW Nevada Solar One project) and Spain (the ANDASOL projects, 50 MW each with 8 h thermal storage) started operation in 2007/2008. New collectors have been developed, but all are showing similar dimensions as either the LS2 or the LS3 collector. One reason for this is the limited availability of key components, mainly the parabolic shaped mirrors and heat collection elements. However, in order to reduce cost, solar power projects are getting larger and larger. Several projects in the range of 250 MW, with and without thermal storage system, are going to start construction in 2011, requiring solar field sizes of 1 to 2.5 Million m2. FLABEG, market leader of parabolic shaped mirrors and e.g. mirror supplier for all SEGS plants and most of the Spanish plants, has started the development of a new collector generation to serve the urgent market needs: lower cost and improved suitability for large solar fields. The new generation will utilize accordingly larger reflector panels and heat collection elements attended by advanced design, installation methods and control systems at the same time. The so-called ‘Ultimate Trough’ collector is showing an aperture area of 1’667 m2 (17’944 ft2), with an aperture width of 7.5 m (24.6 ft). Some design features are presented in this paper, showing how the new and huge dimensions could be realized without compromising stiffness, and bending of the support structure and improving the optical performance at the same time. Solar field layouts for large power plants are presented, and solar field cost savings in the range of 25% are disclosed.

Hydrogen demand has already significantly increased due to the industry needs. Mature technologies based on fossil fuels are not satisfactory due to greenhouse gas concerns. In response, a range of advanced processes are being developed throughout the world.Within the 'International Energy Agency -Hydrogen Implementing Agreement -Task 25', a multicriteria methodology was developed for the evaluation of high temperature hydrogen production processes. The aim is to guide R&D strategy by highlighting to which extent the processes may appear promising. The method that was developed is based on the elimination and choice translating the reality (ELECTRE). This study has conducted a first pass application to hydrogen production and highlights the importance of significant weightings and discriminating criteria.Decision makers can apply this method to extract their own subset of processes from the alternatives, according to their system of values defined through the selection of criteria and the associated weights.

Abstract:The search for a sustainable, CO 2 -free massive hydrogen production route is a strong need, if one takes into account the world-wide increasing energy demand, the deterioration of fossil fuel reserves and in particular the increasing CO 2 concentration leading to global warming.Thermo-chemical cycles for water splitting are considered as a promising alternative of emission-free routes of massive hydrogen production -with potentially higher efficiencies and lower costs compared to alkaline electrolysis of water.The hybrid-sulphur cycle was chosen as one of the most promising cycles from the 'sulphur family' of processes. Different process schemes using concentrated sunlight or nuclear generated heat or a combination of both have been elaborated and analysed by a comparative techno-economic study with regard to their potential of a large-scale hydrogen production. Options for a hybridisation of the energy supply between solar and nuclear have been also investigated, particular focused on the coupling of concentrated solar radiation into a round-the-clock operated process.Process design and simulation, industrial scale-up assessments including safety analysis and cost evaluations were performed to analyse reliability and potential of those process concepts.Keywords: thermochemical cycle; sulphur; hybrid sulphur cycle; solar; economics; sulphur-iodine cycle; sulphuric acid; process modelling. Potential of hybridisation of the thermochemical hybrid-sulphur cycle 179Reference to this paper should be made as follows: Monnerie, N., Schmitz, M., Roeb, M., Quantius, D., Graf, D., de Lorenzo, D. and Sattler, C. (2011) 'Potential of hybridisation of the thermochemical hybrid-sulphur cycle for the production of hydrogen by using nuclear and solar energy in the same plant', Int.

Abstract:The European FP7 project HycycleS focuses on providing detailed solutions for the design of specific key components for sulphur-based thermochemical cycles for hydrogen production. The key components necessary for the high temperature part of those processes, the thermal decomposition of H 2 SO 4 , are a compact heat exchanger for SO 3 decomposition for operation by solar and nuclear heat, a receiver-reactor for solar H 2 SO 4 decomposition, and membranes as product separator and as promoter of the SO 3 decomposition. Silicon carbide has been identified as the preferred construction material. Its stability is tested at high temperature and in a highly corrosive atmosphere. Another focus is catalyst materials for the reduction of SO 3 . Requirement specifications were set up as basis for design and sizing of the intended prototypes. Rigs for corrosion tests, catalyst tests and selectivity of separation membranes have been designed, built and completed. Prototypes of the mentioned components have been designed and tested.Keywords: sulphur; catalyst; silicon carbide; membranes; thermochemical cycle.Reference to this paper should be made as follows: Roeb, M., Thomey, D., Graf, D., Sattler, C., Poitou, S., Pra, F., Tochon, P., Mansilla, C., Robin, J-C., Le Naour, F., Allen, R.W.K., Elder, R., Atkin, I., Karagiannakis, G., Agrafiotis, C., Konstandopoulos, A.G., Musella, M., Haehner, P., Giaconia, A., Sau, S., Tarquini, P., Haussener, S., Steinfeld, A., Martinez, S., Canadas, I., Orden, A., Ferrato, M., Hinkley, J., Lahoda, E. and Wong, B. (2011) 'HycycleS: a project on nuclear and solar hydrogen production by sulphur-based thermochemical cycles ', Int. J. Nuclear Hydrogen Production and Applications, Vol. 2, No. 3, Sabine Poitou studied Chemical Engineering at ENSIC (Ecole Nationale Supérieure des Industries Chimiques) in the National Polytechnic Institute of Lorraine (1991Lorraine ( -1994. Working at the CEA since 1998 as Research Engineer, she was involved on nuclear waste treatment and conditioning studies until 2007. Since 2008, her activity has concentrated on industrial development of hydrogen production with nuclear reactor coupled processes. George Karagiannakis received his PhD in Chem. Eng., at the Aristotle Univ. of Thessaloniki, Greece. He has been an Affiliated Researcher at APTL since 2006 and a member of the Nanoparticles and Catalysts Group. He has expertise in catalytic and electrocatalytic studies, with emphasis in those involving hydrogen productions. He has participated in several national and EU research projects.Christos Agrafiotis is a Principal Researcher at CPERI, Chemical Engineer. He received his PhD in Chem. Eng., from SUNY, Buffalο, USΑ. He has more than 15 years of expertise in powder synthesis and catalytic coating of monolithic reactors, participated in several EU-and nationally-funded research projects in these areas, and he is the author of more than 40 relevant publications in international journals and proceedings. Athanasios Konstandopoulos is the Director of APTL and C...

The potential of hydrogen to be the energy carrier of the future is widely accepted. Today more than 90% of hydrogen is produced by cost effective technologies from fossil sources mainly by steam reforming of natural gas and coal gasification. But hydrogen is not important as an energy carrier yet — it is mainly a chemical. To finally benefit from hydrogen as a fuel it has to be produced greenhouse gas free in large quantities. Therefore these two tasks have to be connected by a strategy incorporating transition steps. Solar thermal processes have the potential to be the most effective alternatives for large scale hydrogen production in the future. Therefore high temperature solar technologies are under development for the different steps on the stair to renewable hydrogen. This paper discusses the strategy based on the efficiencies of the chosen solar processes incorporating carbonaceous materials as well as processes based on water splitting. And the availability of the technologies. A comparison with the most common industrial processes shall demonstrate which endeavors have to be done to establish renewable hydrogen as a fuel.