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AbstractThe potential impacts of future climate scenarios on water balance and flow regime are presented and discussed for a temporary river system in southern Italy. Different climate projections for the future (2030–2059) and the recent conditions (1980–2009) were investigated. A hydrological model (Soil and Water Assessment Tool) was used to simulate water balance at the basin scale and streamflow in a number of river sections under various climate change scenarios, based on different combinations of global and regional models (global circulation models and regional climate models). The impact on water balance components was quantified at the basin and subbasin levels as deviation from the baseline (1980–2009), and the flow regime alteration under changing climate was estimated using a number of hydrological indicators. An increase in mean temperature for all months between 0.5–2.4 °C and a reduction in precipitation (by 4–7%) was predicted for the future. As a consequence, a decline of blue water (7–18%) and total water yield (11–28%) was estimated. Although the river type classification remains unvaried, the flow regime distinctly moves towards drier conditions and the divergence from the current status increases in future scenarios, especially for those reaches classified as I‐D (ie, intermittent‐dry) and E (ephemeral). Hydrological indicators showed a decrease in both high flow and low flow magnitudes for various time durations, an extension of the dry season and an exacerbation of extreme low flow conditions. A reduction of snowfall in the mountainous part of the basin and an increase in potential evapotranspiration was also estimated (4–4.4%). Finally, the paper analyses the implications of the climate change for river ecosystems and for River Basin Management Planning. The defined quantitative estimates of water balance alteration could support the identification of priorities that should be addressed in upcoming years to set water‐saving actions.

In this paper, we address the problem of determining the optimal day-ahead generation profile for a wind power producer by exploiting wind speed forecasts provided by a meteorological service. In the considered framework, the wind power producer is called to take part in the responsibility of system operation by providing day-ahead generation profiles and undergoing penalties in case of deviations from the schedule. Penalties are applied only if the delivered hourly energy deviates from the schedule more than a given relative tolerance. The optimal solution is obtained analytically by formulating and solving a stochastic optimization problem aiming at maximizing the expected profit. The proposed approach consists in exploiting wind speed forecasts to classify the next day into one of several predetermined classes, and then selecting the optimal solution derived for each class. The performance of the bidding strategy is demonstrated using real data from an Italian wind plant and weather forecasts provided by a commercial meteorological service.

We present a MEMS-based unimorph silicon/PZT thick film vibrational energy harvester with an integrated proof mass. We have developed a process that allows fabrication of high performance silicon based energy harvesters with a yield higher than 90%. The process comprises a KOH etch using a mechanical front side protection of an SOI wafer with screen printed PZT thick film. The fabricated harvester device produces 14.0 µW with an optimal resistive load of 100 kΩ from 1g (g=9.81 m s−2) input acceleration at its resonant frequency of 235 Hz.

Abstract In this paper, a medium-term load forecasting model is proposed, intended to be used for the extrapolation of loads containing a small proportion of air conditioners. The main feature of the proposed model is the decomposition of weekly load observations into two independent components: trend line and seasonal variations. The trend line is described by the combination of the polynomial regression and the first-order autoregressive model. The parameters of this model are estimated with the aid of the generalized least-squares method. The seasonal component is modeled via a discrete model, where the weather sensitive cycle is separated from the weather insensitive one. A linear regression model is further proposed in order to associate weather sensitive variations with the exogenous weather variable (temperature). This procedure enabled a simple and efficient convolution of all load components into a single forecasting model. The whole methodology is verified on a real-life example of the peak-load consumption within the power system of former Yugoslavia.

Artículos en revistas In this paper we apply stochastic dual dynamic programming decomposition to a nonconvex multistage stochastic hydrothermal model where the nonlinear water head effects on production and the nonlinear dependence between the reservoir head and the reservoir volume are modeled. The nonconvex constraints that represent the production function of a hydro plant are approximated by McCormick envelopes. These constraints are split into smaller regions and the McCormick envelopes are used for each region. We use binary variables for this disjunctive programming approach and solve the problem with a decomposition method. We resort to a variant of the L-shaped method for solving the MIP subproblem with binary variables at any stage inside the stochastic dual dynamic programming algorithm. A realistic large-scale case study is presented. info:eu-repo/semantics/publishedVersion

Fil: Bavio, Marcela Alejandra. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Fisica e Ingenieria del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Tandil. Centro de Investigaciones en Fisica e Ingenieria del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernacion. Comision de Investigaciones Cientificas. Centro de Investigaciones en Fisica e Ingenieria del Centro de la Provincia de Buenos Aires; Argentina

Artículos en revistas Liberalization policies, the challenges of integrating distributed generation resources, and the recent flattening of electricity demand due to the economic crisis and technological change have led to lower returns for European electricity suppliers. Innovative and sustainable business models are needed to serve electricity customers while reflecting the operational needs of the system and maintaining supplier financial viability. This paper describes a novel model of Integrated Energy Services that encompasses distributed generation (DG) and demand response (DR) resources for industrial customers. We further reflect on some of the market opportunities and regulatory drivers for the development of similar schemes across Europe. info:eu-repo/semantics/publishedVersion

Abstract The aerodynamic design of small wind turbines for the urban setting attracts increasing interest within the scientific community, but the adoption of a proper control strategy may be just as important, especially in high turbulent winds, where such energy conversion devices should ideally operate. As a matter of fact, the mere rotor efficiency is meaningless unless the system has also the capability of rapidly changing its angular speed in case of a sudden variation of the wind velocity, to reach a new optimal operating condition. This work will attempt neither to develop dynamic simulation models nor to examine possible turbine control strategies, being the focus much broader, namely, the investigation of operational contexts where the peculiar inertial characteristics of wind turbines would compromise any form of robust control. Inertial and operational data of commercially available turbines (characterized by both horizontal and vertical-axis architectures), as well as the results disseminated in various literature sources, operational experiences and design best practices, are here collected under one cover and compared, thus deriving some basic and fundamental relations between rotor inertia and angular acceleration, highlighting how, in several cases, a control strategy based on the continuous tracking of the optimal operating condition is most unlikely. Such considerations raise the question of whether the problem of inertia renders futile many prevailing theories about small wind turbine operation and plans for implementing new control strategies, especially as far as vertical axis architectures are concerned. On the other hand, some constructive advice is also presented, in the form of a means to compare the effective performances of different turbines, in a given installation site, with respect to their nominal (i.e. steady state, or wind tunnel) behaviour. As a final result, a new bound for a reliable estimation of the amount of energy a wind turbine will generate in a specific site is suggested, based on the comparison between a representative time scale of the installation site and the response time of the candidate wind turbine.