Future trajectories of renewable energy consumption in the European Union

Renewable energy sources (RESs) are able to reduce the European Union (EU)’s dependence on foreign energy imports, also meeting sustainable objectives to tackle climate change and to enhance economic opportunities. Energy management requires a quantitative analysis and the European Commission follows the performance of each Member State (MS) in order to define the corrective measures towards 2020 targets. Starting from historical data reported in the Eurostat database and through a mathematical model, this work proposes future trajectories towards 2020 of the share of energy from renewables (REs) in terms of gross final energy consumption (GFEC). Furthermore, a quantitative analysis based on two indices—(i) the share of REs in GFEC, and (ii) gross final renewable energy consumption (GFREC) per capita—permits a comparison among 28 MSs. The share of REs in GFEC in EU 28 varies from 19.4% to 21.8% in future trajectories towards 2020. Sweden and Finland occupy the top part of the ranking, while six MSs (Belgium, France, Ireland, Luxembourg, The Netherlands, and the United Kingdom) are not able to reach the 2020 targets

Estimation accuracy vs. engineering significance of contact parameters for solid dampers

Abstract All numerical models of friction-damped bladed arrays require knowledge or information of contact-friction parameters. In the literature, these parameters are typically tuned so that the experimental Frequency Response Function (FRF) of a damped blade matches its numerical counterpart. It is well known that there exist multiple combinations of contact parameters capable of satisfying a given experimental-numerical FRF match. A better approach towards a finer tuning could be based on directly measuring contact forces transmitted between blade platforms through the damper: in this case friction coefficients are estimated through tangential over normal force components during those hysteresis segments which are safely identified as being in a slip condition. This has been applied by these authors to rigid bar (solid) dampers. Unfortunately, the four contact stiffness values (left and right damper-platform contact, normal and tangential) are more than the measurements available in the technique presented by these authors. Therefore, the problem is underdetermined. The purpose of this paper is twofold, i.e., to propose an alternative way to estimate contact stiffness values (i.e. thus solving the under-determinacy mentioned above) and to check the effective significance of such estimates from a practical engineering point of view. The contact parameter estimation technique proposed by these authors produces, for each contact parameter, a best-fit value and an uncertainty band. It will be shown that the uncertainty affecting each contact parameter results in an uncertainty on the equivalent damping and stiffness indicators at blade level which is lower than 5%

Latest Investigations on Underplatform Damper inner Mechanics

Underplatform dampers (UPDs) are widely used as a source of friction damping and are frequently incorporated into compressors and turbines for both aircraft and power-plant applications to mitigate the effects of resonant vibrations on fatigue failure. Due to the nonlinear nature of dry friction, in general dynamic analysis of structures constrained through frictional contacts is difficult, direct time integration with commercial finite element codes may not be a suitable choice given the large computation times. For this reason, ad hoc numerical codes have been developed in the frequency domain. Some authors prefer a separate routine in order to compute contact forces as a function of input displacements, others include the damper in the FE model of the bladed array. All numerical models, however, require knowledge or information of contact -friction parameters, which are established either through direct frictional measurements, done with the help of single contact test arrangements, or by fine tuning the parameters in the numerical model and comparing the experimental response of damped blade against its computed response. The standard approach is to fine-tune and experimentally validate the UPDs models by comparing measured and calculated vibration response of blade pairs. To our knowledge, nobody has ever attempted to directly measure the forces transmitted between the platforms through the damper and the relative damper-platform movement. In the light of recent results from direct measurements on dampers it is evident that a dedicated routine for the damper mechanics is an effective tool to capture those finer details which are essential to an appropriate description of damper behaviour. This was made possible by the successful effort of the present authors to accurately measure the forces transmitted between the platforms through the damper, to connect them with the relative platforms movement and to use the findings for the validation of the numerical model. The cross-comparison between numerical and experimental results allows to gain a clear understanding of all contact events (stick, slip, lift) which take place during the cycle, and on how they influence the damping performance

ANALYSING THE CAPACITY OF A TRANSPORTATION NETWORK. A GENERAL THEORETICAL APPROACH

Estimation of transportation network capacity is important in analysing network performance. In the existing literature, the capacity of a network is defined in conditional terms as a theoretical construct called “reserve capacity”. This may be limited because, when considering local land-use development, the hypothetical uniform increase in O-D flows is not always realistic. This paper, introducing the concept of “capacity function”, proposes a generalized concept of road network capacity which does not require information on either current O-D demand or the corresponding growth trend. Attention focuses on deterministic and stationary situations in which only one path is available for each O-D pair. Some examples regarding simple study cases demonstrate the capacity of this approach to solve problems and, consequently, to contribute to the analysis of network performance

Numerical and experimental investigations on underplatform damper mechanics

So called under-platform dampers are widely used as a source of friction damping to mitigate resonance in gas turbine blades and avoid service failures. Due to the high computational cost of performing dynamic analysis of structures constrained through frictional contacts, ad hoc numerical codes have been developed in the frequency domain. Whatever the numerical model, it requires knowledge of contact-friction parameters, which are established either through single contact frictional measurements, or by tuning the damper parameters though comparison of the experimental response of damped blade against its computed response or, else, by fine tuning the damper parameters by comparing the measured v. the calculated hysteresis cycle. The last one is these authors’ choice. Equipment and method are described accordingly

The sustainable development of mobility in the green transition: Renewable energy, local industrial chain, and battery recycling

The transportation sector has a strong negative impact on the environment and therefore requires new sustainable development measures. This paper proposes a new indicator of sustainability in transport obtained through a multi-criteria analysis based on Eurostat data and a panel of 10 academics. The results show a positive per formance of Sweden in the period 2015–2019 and a small number of countries above the European average. Furthermore, a quantitative analysis based on these experts identifies the critical success factors associated with purchasing electric vehi cles. The greatest importance is assigned to purchase cost, followed by battery autonomy. Our analysis proposes that electric vehicles are unable to achieve a sus tainable transition unless three conditions are met: (i) use of renewable sources, (ii) local industrial development of the sector, and (iii) battery recycling. Therefore, Europe urgently needs to realize new industrial activities and avoid social unsustain ability. The long-term objective of a policy plan is to promote independence from external sources of energy, materials, and other resource

Dataset for assessing the economic performance of a residential pv plant. The analysis of a new policy proposal

This data article aims at providing a data description about the manuscript entitled “The post COVID-19 green recovery in practice: assessing the profitability of a policy proposal on residential photovoltaic plants”. The definition of a business plan is a complex decision because the choice of the input data significantly influences the economic assessment of a project. An Excel file is used to construct an economic model based on the Discounted Cash Flow (DCF) methodology using Net Present Value (NPV) as an indicator. The choice of input data is defined by literature analysis, and policy proposals are identified by the Revival Decree adopted by Italian Government to contrast human and economic shock effected by COVID-19. The aggregation of these data enabled us to obtain both baseline and alternative scenarios to define if the realization of a residential photovoltaic (PV) plant is economically feasible. Similar data can be obtained for other countries according to the policy actions adopted, and this work can be easily replicated in different geographical contexts and considering varying categories of stakeholders (e.g., consumers, which are called upon to implement a green transition)