• Energy Research

In this paper, we deal with the design of a sustainable network of charging stations for electric vehicles circulating in an urban area. The major obstacles to E-Mobility (EM) development are still to be found into heated debates both in the scientific and industrial field and into a lacking of a widespread, accessible and homogeneous recharge infrastructure for the electric vehicles. In this work, we face the problem known as location optimization of charging stations and offer a heuristic method to design a sustainable infrastructure for the electric vehicles charging into urban contexts. In particular, the research can help mayors and governors of cities to take decisions concerning the number, the type and the placement of charging stations, taking into account the estimated hourly demand of charging services. Obviously, the design of an appropriate network includes the definition of all the needed costs to build the infrastructure and then the analysis of economic sustainability of the network basing on the revenues coming from estimated demand. The profitability of single charging stations is one of the main criteria to choose for the installation of a station. In this study we assume homogeneous pricing policy like in a monopoly scenario among charging stations. Future research can investigate on the effect of different prices applied by stations in the network design.

The main goal of the Divertor Tokamak Test facility (DTT) is to explore alternative power exhaust solutions for DEMO. The principal objective is to mitigate the risk of a difficult extrapolation to fusion reactor of the conventional divertor based on detached conditions under test on ITER. The task includes several issues, as: (i) demonstrating a heat exhaust system capable of withstanding the large load of DEMO in case of inadequate radiated power fraction; (ii) closing the gaps in the exhaust area that cannot be addressed by present devices; (iii) demonstrating how the possible implemented solutions (e.g., advanced divertor configurations or liquid metals) can be integrated in a DEMO device.In view of these goals, the basic physical DTT parameters have been selected according to the following guidelines: (i) edge conditions as close as possible to DEMO in terms of dimensionless parameters; (ii) flexibility to test a wide set of divertor concepts and techniques; (iii) compatibility with bulk plasma performance; (iv) an upper bound of 500 M€ for the investment costs.

Abstract This paper deals with the modelling of the 2 × 25 kV – 50 Hz high speed railway supply system. The proposed approach extends the traditional multi-conductor transmission line approach typically used for high speed railway systems, which is based on the assumption of overhead conductors. More specifically, this approach models the system by considering the presence of both overhead and buried conductors. Analytical formulations to calculate self and mutual line parameters are used. A numerical simulation allows evidencing the different results when the simplified and the detailed modelling approaches are adopted. A sensitivity analysis to point out the influence of the finitely conductive ground is also proposed.

EU-DEMO is a European project, having the ambitious goal to be the first demonstrative power plant based on nuclear fusion. The electrical power that is expected to be produced is in the order of 700–800 MW, to be delivered via a connection to the European High Voltage electrical grid. The initiation and control of fusion processes, besides the problems related to the nuclear physics, need very complex electrical systems. Moreover, also the conversion of the output power is not trivial, especially because of the inherent discontinuity in the EU-DEMO operations. The present article concerns preliminary studies for the feasibility and realization of the nuclear fusion power plant EU-DEMO, with a special focus on the power electrical systems. In particular, the first stage of the study deals with the survey and analysis of the electrical loads, starting from the steady-state loads. Their impact is so relevant that could jeopardy the efficiency and the convenience of the plant itself. Afterwards, the loads are inserted into a preliminary internal distribution grid, sizing the main electrical components to carry out the power flow analysis, which is based on simulation models implemented in the DIgSILENT PowerFactory software.

The EU DEMO Plant Electrical System (PES) main scopes are to supply all the plant electrical loads and to deliver to the Power Transmission Grid (PTG) the net electrical power generated. The studies on the PES during the Pre- Concept Design (PCD) Phase were mainly addressed to understand the possible issues, related to the special features both of the power generated, with respect to a power plant of the same size, and of the power to be supplied to the electrical loads. For this purpose, the approach was to start the design of the different PES components adopting technologies already utilized in fusion experiments and in Nuclear Power Plants (NPP) to verify their applicability and identify possible limits when scaled to the DEMO size and applied to the specific pulsed operating conditions. This work is not completed, however several issues have been already identified related to the pulsed operation of the turbine generator, the large amount of recirculation power, the very high peaks of active power required for the plasma formation and control, the huge reactive power demand, if thyristor converter technology was adopted to supply the superconducting coils, etc.. The paper gives an overview on the features and scope of the PES and its subsystems, on the main achievements during the Pre- Concept Design (PCD) Phase, on the challenges for the development of the conceptual design in the next framework program and on the plan to face them.

The present paper shows the results of the investigation about the effects of the flux-expansion variation at the inner strike point location on the tungsten content in the plasma core, and on the bulk radiation in JET-ILW. The divertor geometries have been designed using the plasma equilibrium code CREATE-NL. The designed divertor geometries were experimentally achieved via a suitable optimization of the divertor coils current on a few discharges with similar additional heating. Diagnostics were used to examine: the tungsten source from the divertor tiles in both inter-ELM and intra-ELM phases, the tungsten content and profile shape inside the plasma core, and the total radiation. Preliminary results suggest that there is not a strong impact of the flux expansion on the tungsten erosion at the strike point. A discharge with high flux compression shows nonetheless a slight increase in core tungsten concentration but this might also be the result of changes in ELMs frequency due to flux expansion variation. The effect on ELMs dynamic has been clearly observed making more difficult the present analysis and should be further studied in future experiments. Edge analysis performed with the SOLEDGE2D code seems to exclude a significant variation of edge transport with flux expansion, pointing to an indirect effect on pumping efficiency and consequently on edge density.