A discussion of possible approaches to the integration of thermochemical storage systems in concentrating solar power plants

One of the most interesting perspectives for the development of concentrated solar power (CSP) is the storage of solar energy on a seasonal basis, intending to exploit the summer solar radiation in excess and use it in the winter months, thus stabilizing the yearly production and increasing the capacity factor of the plant. By using materials subject to reversible chemical reactions, and thus storing the thermal energy in the form of chemical energy, thermochemical storage systems can potentially serve to this purpose. The present work focuses on the identification of possible integration solutions between CSP plants and thermochemical systems for long-term energy storage, particularly for high-temperature systems such as central receiver plants. The analysis is restricted to storage systems potentially compatible with temperatures ranging from 700 to 1000 ◦C and using gases as heat transfer fluids. On the basis of the solar plant specifications, suitable reactive systems are identified and the process interfaces for the integration of solar plant/storage system/power block are discussed. The main operating conditions of the storage unit are defined for each considered case through process simulation

DTT - Divertor Tokamak Test facility: A testbed for DEMO

The effective treatment of the heat and power exhaust is a critical issue in the road map to the realization of the fusion energy. In order to provide possible, reliable, well assessed and on-time answers to DEMO, the Divertor Tokamak Test facility (DTT) has been conceived and projected to be carried out and operated within the European strategy in fusion technology. This paper, based on the invited plenary talk at the 31st virtual SOFT Conference 2020, provides an overview of the DTT scientific proposal, which is deeply illustrated in the 2019 DTT Interim Design Report

DTT - Divertor Tokamak Test facility - Interim Design Report

The “Divertor Tokamak Test facility, DTT” is a milestone along the international program aimed at demonstrating – in the second half of this century – the feasibility of obtaining to commercial electricity from controlled thermonuclear fusion. DTT is a Tokamak conceived and designed in Italy with a broad international vision. The construction will be carried out in the ENEA Frascati site, mainly supported by national funds, complemented by EUROfusion and European incentive schemes for innovative investments. The project team includes more than 180 high-standard researchers from ENEA, CREATE, CNR, INFN, RFX and various universities. The volume, entitled DTT Interim Design Report (“Green Book” from the colour of the cover), briefly describes the status of the project, the planning of the design future activities and its organizational structure. The publication of the Green Book also provides an occasion for thorough discussions in the fusion community and a broad international collaboration on the DTT challenge

Decomposition of hydrogen iodide in the S–I thermochemical cycle over Ni catalyst systems

The sulphur–iodine thermochemical cycle for hydrogen production has been investigated by ENEA (Agency of New Technologies, Energy and Environment, Italy) over the last 5 years, with a particular focus on chemical aspects. Regarding the hydrogen iodide decomposition, four γ-alumina-supported nickel catalysts were produced and characterized, and then tested in terms of catalytic activity and stability by means of a tubular quartz reactor. In particular, the relationship between catalytic activity and preparation procedure was investigated. From the experimental data acquired, it can be concluded that three of the four catalysts tested demonstrated high catalytic activity, since hydrogen iodide conversion was almost coincident with the theoretical equilibrium value. On the other hand, for all the catalysts, a gradual but considerable deactivation phenomenon was observed at 500 °C, while at a temperature higher than 650 °C the catalytic activity was recovered

Student Privacy: The Next Frontier - Emerging & Future Privacy Issues in K-12 Learning Environments

Building off several prior working meetings which mapped and considered the implications of the new and rapidly evolving ecosystem of networked technology being used with education (“ed tech”), the Berkman Center for Internet & Society’s Student Privacy Initiative convened a conversation in May 2015 among multiple stakeholders, including, but not limited to, K-12 educators, district administrators, academics, policy makers, and industry representatives. This working meeting was envisioned as one in a series of conversations which deepens our understanding of emerging and future privacy issues in K-12 learning environments, both formal and informal. Future conversations may focus on specific topics within the broader spectrum of issues relating to student privacy; this particular working meeting prioritized practicality over theoretical discussion, emphasizing the evolving experiences of K-12 administrators, educators, and students. In order to evaluate the challenges and opportunities fostered by the next generation of ed tech, participants were asked to consider the following four layers of the ed tech ecosystem, each of which informs the others in myriad ways: Technological Infrastructure: What kind of technology can be considered “ed tech”? This layer encompasses cloud infrastructure, the Internet of Things, sensor networks, and other new technologies that facilitate connected learning environments (which transcend the traditional classroom set-up, disturb hierarchies, and foster peer-to-peer interactions) and other educational innovations within brick and mortar classrooms, thereby shaping the collection and use of student/educational data. Data: What kinds of data are being collected, and how/by whom are they being used? This layer includes the opportunities afforded by learning analytics (the aggregation of data about learners, offering the potential benefit of individualized learning trajectories and the potential challenge of limiting or discriminatory “tracking”), as well as other uses by educators, administrators, and other stakeholders of individual and cohort-wide student data previously unimaginable in both its breadth and depth. Organizational Structures: Where does learning take place today? This layer maps the institutional forms of current and future educational institutions, from traditional schoolhouses to informal learning environments, which can be situated within the context of schools, cities, libraries, and elsewhere -- and are perhaps best understood as part of the connected learning ecosystem. Norms and values: How do we want ed tech to be used in the classroom, and what are our expectations for/desires of privacy? This layer reflects those principles, policies, pedagogies, and practices that do or should animate the goals, implementation, and stakeholder experiences of twenty-first century digital education in its various iterations. Keeping these layers in mind, discussion ranged widely across numerous themes, reflecting the participants’ diverse backgrounds and perspectives. This report seeks to summarize the conversation’s main themes and highlight suggestions for future action. In the following section, the main themes and observations are considered, including issues dealt with explicitly and at length, in addition to those that more quietly (and perhaps implicitly) surfaced at multiple points during the day. And although the third section concerns suggested areas for moving forward, these are meant to be understood as key highlights, and not a comprehensive summary

Round Robin Test on Enthalpies of Redox Materials for Thermochemical Heat Storage

Among systems proposed as suitable for thermochemical heat storage (TCS), redox oxides merit significant attention for high temperature applications in Concentrating Solar Power (CSP) plants. The specific enthalpy of the reaction is a key parameter to establish the storage capacity of the system. Consequently, there is considerable practical interest in accurately determining this parameter. Discrepancies in the referenced enthalpies may arise from inadequate protocols and/or sets-ups for measuring thermodynamic properties at high temperatures, or the presence of impurities in the samples. This work presents a round robin test conducted by eight institutions, research centers and companies during 2015-2016 in order to develop a standard procedure for the measurement of enthalpies in the relevant thermochemical processes at high temperature. The initiative was organized within the Working Group on Thermal Storage (Activity on “Materials for Thermal Storage”) in SolarPACES Task III

Mayenite-supported CaO for thermochemical storage applications. Ageing time effect over conversion

Thermo Chemical Storage systems (TCS) are gaining an increasing interest in the field of long term-thermal energy storage, thanks to their potential applicability in the Concentrated Solar Power technology to increase the electricity generation flexibility, and in different energy sectors operating at medium/high temperature levels, including the industrial one, to optimize the heat recovery and accumulation. As for the high temperature (HT) applications, research is currently focused on oxides and hydroxides-based as well as carbonates-based ones. The latter have been mainly proposed in the literature as CaO/CaCO3 system, initially applied to CO2 capture technologies. However, in order to overcome the intrinsic ciclability limitation observed for natural dolomite and limestone, synthetic sorbents have been recently developed, like the calcium oxide supported on Mayenite (Ca12Al14O33), which has also been investigated by ENEA, showing a significant durability. Despite a fast reaction kinetics and a high conversion extent (up to 80-90% in long isothermal conditions), both in carbonation and calcination steps, this material has shown interaction with air moisture and ambient CO2, affecting the reproducibility of the tests. The objective of the present work is to assess the ambient air stability of the CaO/Mayenite system, to verify the need of pre-treatment processes. At this purpose, CaO/Mayenite powder was synthesized, morphologically characterized and tested thermogravimetrically at different ageing level, namely 30 days and 60 day. The experimental campaign confirms that carbonation conversion remarkably enhances after 30 days of ambient air exposure, while it remains unvaried for further ageing times as a consequence of material properties stabilization. This result indicates that an initial air exposure of about 1 month is sufficient to guarantee a substantial reproducibility of the material performances and no energy consuming pre-treatments are required to stabilize the material response

Hydrogen production by the sodium manganese ferrite thermochemical cycle-experimental rate and modeling

The sodium manganese ferrite thermochemical cycle for hydrogen production by water splitting can successfully operate in a relatively low temperature range (1023-1073 K) and has a high potential for coupling with the solar source using conventional structural materials. With the aim of implementing the cycle in a solar reactor, the hydrogen evolution rate from the reactive mixture measured in laboratory apparatus has been modeled by using a shrinking-core model. Such a model proved to adequately describe the rate of hydrogen production in the studied temperature and water concentration range. The model was extended to predict the behavior of the reactive mixture subjected to different experimental conditions. © 2014 American Chemical Society