1,721,805 research outputs found
Strategies for the integration of intermittent renewable energy sources in the electrical system
No full textEurope is pursuing an aggressive programme to increase its share of renewable energy source (RES). However, the integration of intermittent RES (wind and photovoltaic) in the electrical system requires either maintaining in operation thermal backup systems or providing a substantial amount of electricity storage. We analyze the Italian electricity data for the year 2013 provided by the transmission system operator TERNA. The present level of intermittent RES power is scaled-up to a level at which it generates an amount of electricity equal to the annual demand. While a substantial reduction of the energy annually produced by fossil backup systems (and the associated CO2 emission) with respect to the no-RES case is possible in many scenarios considered here, the backup power is generally only marginally reduced below the value in the absence of RES. The strategy proposed is based on the combination of a modest amount of storage (0.5-5TWh) and base-load power (6-15GW, to be used during the seasons of low RES production). In this way the non-RES installed power can be reduced from ∼ 50 GW to less than 15GW and could be covered by a combination of biomass and nuclear energy without any CO2 emission. © 2016, Società Italiana di Fisica and Springer-Verlag Berlin Heidelberg
Overview of the JET results with the ITER-like wall
No full textFollowing the completion in May 2011 of the shutdown for the installation of the beryllium wall and the tungsten divertor, the first set of JET campaigns have addressed the investigation of the retention properties and the development of operational scenarios with the new plasma-facing materials. The large reduction in the carbon content (more than a factor ten) led to a much lower Zeff (1.2–1.4) during L- and H-mode plasmas, and radiation during the burn-through phase of the plasma initiation with the consequence that breakdown failures are almost absent. Gas balance experiments have shown that the fuel retention rate with the new wall is substantially reduced with respect to the C wall. The re-establishment of the baseline H-mode and hybrid scenarios compatible with the new wall has required an optimization of the control of metallic impurity sources and heat loads. Stable type-I ELMy H-mode regimes with H98,y2 close to 1 and βN ~ 1.6 have been achieved using gas injection. ELM frequency is a key factor for the control of the metallic impurity accumulation. Pedestal temperatures tend to be lower with the new wall, leading to reduced confinement, but nitrogen seeding restores high pedestal temperatures and confinement. Compared with the carbon wall, major disruptions with the new wall show a lower radiated power and a slower current quench. The higher heat loads on Be wall plasma-facing components due to lower radiation made the routine use of massive gas injection for disruption mitigation essential
A Simple Model for Impurity Production in Tokamaks
No full textA simple analytical model is presented for the plasma in the region outside the limiter which describes the impurity ions transport and production in the tokamak scrape‐off layer. The equations of the model are solved analytically in the test particle approximation for the simple SOL configurations. A discussion of the solutions for different plasma parameters and target materials is presented. Copyright © 1994 WILEY‐VCH Verlag GmbH & Co. KGa
On the interaction of ion Bernstein waves with alpha particles
No full textAlpha channelling is a possible mechanism to transfer the energy of the fusion generated alpha particles directly to the thermal ion population through a wave propagating in the plasma. The interaction of ion Bernstein waves with a population of alpha particles is investigated to determine the conditions that maximize the absorption of the wave by the thermal ions and minimize the absorption by the thermal electrons under reactor relevant conditions. The ray trajectories equations are analytically and numerically solved beyond the mode conversion layer and the optimal conditions for alpha channelling are determined
Summary of the 18th International Atomic Energy Agency Fusion Energy Conference transport and boundary physics
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