The Monge problem with vanishing gradient penalization: Vortices and asymptotic profile

We investigate the approximation of the Monge problem (minimizing ?????|T(x)???x|d??(x) among the vector-valued maps T with prescribed image measure T_\\#\mu) by adding a vanishing Dirichlet energy, namely ???????|DT|2, where ?????0. We study the ??-convergence as ?????0, proving a density result for Sobolev (or Lipschitz) transport maps in the class of transport plans. In a certain two-dimensional framework that we analyze in details, when no optimal plan is induced by an H1 map, we study the selected limit map, which is a new "special" Monge transport, different from the monotone one, and we find the precise asymptotics of the optimal cost depending on ??, where the leading term is of order ??|log??

Storage Solutions for Renewable Production in Household Sector

Abstract The penetration of renewable sources, particularly wind and solar, into the grid has been increasing in recent years. As a consequence, there have been serious concerns over reliable and safety operation of power systems. One possible solution, to improve grid stability, is to integrate energy storage devices into power system network: storing energy produced in periods of low demand to later use, ensuring full exploitation of intermittent available sources. Focusing on stand-alone photovoltaic (PV) energy system, energy storage is needed with the purpose of ensuring continuous power flow, to minimize or, if anything, to neglect electrical grid supply. A comprehensive study on a hybrid stand-alone photovoltaic power system using two different energy storage technologies has been performed. This study examines the feasibility of replacing electricity provided by the grid with hybrid system to meet household demand. This paper is a part of an experimental and a theoretical study which is currently under development at University of Bologna. A test facility is under construction, at the University of Bologna, for the experimental characterization of the cogenerative performance of small scale hybrid power systems, composed of micro-CHP systems of different technologies : a Micro Rankine Cycles (MRC), a Proton Exchange Membrane Fuel Cells (PEM-FC), a battery, an electrolyzer and a heat recovery subsystem. The test set-up is also integrated with an external load simulator, in order to generate variable load profiles. This paper presents the theoretical results of the performance simulations developed considering an hybrid system consisting on a photovoltaic array (PV), electrochemical batteries (B) and electrolyzer (HY) with a H2 tank and a Proton Exchange Membrane Fuel Cell (PEM-FC) stack, in case of a household electrical demand. The performance of this system have been evaluated by the use of a calculation code, in-house developed by University of Bologna; future activities will be the tuning of the software with the experimental results, in order to realize a code able to define the correct size of each sub-system, ones the load profile of the utility is known or estimated

Smart District Heating: Distributed Generation Systems' Effects on the Network☆

Abstract The European strategy 20-20-20 – providing for energy efficiency increase, pollutant emissions reduction and fossil fuel consumption reduction – leads to an increasing attention on the concept of smart cities. In this scenario, it is important to consider a possible integration between networks and distributed generation systems – i.e. to realize a bidirectional energy flux at the utilities, giving rise to the so-called smart grid – not only for the electrical sector, but also for the thermal energy field. Therefore, the concept of smart grid could be extended to the heat sector in relation to District Heating Networks (DHNs) and considering thermal energy distributed generation systems, such as solar thermal panels or micro-Combined Heat and Power (micro-CHP) generators. In this study several different layouts for the utilities substations in smart DHNs will be presented and discussed. These layouts have been developed in order to allow the bidirectional exchange of thermal energy at the utilities, optimizing the thermal exchange as function of network design temperatures (for both the supply and the return), of utilities' thermal power requirement and depending on the characteristics of the production system. Further, in this paper the results obtained from the simulations, carried out with the software Intelligent Heat Energy Network Analysis (I.H.E.N.A.) considering the implementation of the elaborated layouts, will be analyzed

Insights for the future of health system partnerships in low- and middle-income countries: a systematic literature review

BACKGROUND: Despite growing support for the private sector involvement in the provision of public health services in Low- and Middle-Income Countries (LMICs), a lack of clear information on the future of the provision of such services restricts the ability of managers and policy-makers to assess how feasible integration between public and private actors may be in these countries. This paper presents a systematic literature review which traces the dynamics and boundaries of public-private partnerships for the healthcare sector in LMICs. METHODS: A total of 723 articles indexed in Scopus were initially submitted to bibliometric analysis. Finally, 148 articles published in several academic journals were selected for independent full-text review by two researchers. Content analysis was made in order to minimise mistakes in interpreting the findings of studies in the sample. RESULTS: Public-private partnerships identified through the content analysis were categorised into four research areas: 1) Transfer of resources; 2) Co-production of health goods and services; 3) Governance networks; 4) Criteria for successful partnership development. CONCLUSIONS: The four main research areas supply suggestions for a future research agenda, and managerial and policy implications for partnerships in LMICs

Comparative Analysis of Renewable Energy Community Designs for District Heating Networks: Case Study of Corticella (Italy)

In recent years, a rapid increase in the adoption of renewable energy sources and in the transition from a centralized electricity generation system to an increasingly distributed one has occurred. Within this scenario, in line with the European directives for achieving the objectives in the field of energy transition and climate change, energy communities are seen as potential contributors. The purpose of this work is to analyze the application potential of the energy community concept associated with district heating networks, leading to better overall energy-economic performance. This was demonstrated for a specific energy community in Italy, and it can be achieved by maximizing internal energy sharing-resulting from the electricity surplus generated by the photovoltaic system-and adopting different strategies that include heat pumps in order to maximize self-consumption and self-sufficiency, as well as to evaluate the most efficient investment in economic terms by exploiting the incentive tariff on shared energy. The results show that the performance of the system can be improved with the proposed design, achieving a significant reduction in the system's energy demand, emissions and costs: compared to the reference case, the use of photovoltaics reduces primary energy demand by approximately 11%, while the addition of the energy community configuration allows emissions to be reduced by nearly 12%, with no additional investment

Performance Increase of a Small-scale Liquefied Natural Gas Production Process by Means of Turbo-expander☆

Abstract In the last years, the growing demand of the energy market has led to the increasing penetration of renewable energy sources in order to achieve the primary energy supply. However, in the next years fossil fuels are expected to remain the dominant energy source, due to the forecasted increase of global energy consumption. In particular, the natural gas is predicted to still play a key role in the energy market, on account of its lower environmental impact than other fossil fuels. Natural gas is currently employed mainly as gaseous fuel for stationary energy generation, but also as liquefied fuel, as an alternative to the diesel fuel, in vehicular applications. Liquefied Natural Gas (LNG) is currently produced in large plants directly located at the extraction sites. The aim of the study is the definition of an optimal small-scale production process for LNG, to be realized – in opposition to the current habit – directly at filling stations. With this purpose, two different LNG production layouts have been proposed and investigated within a thermodynamic analysis: starting from a Joule-Thompson LNG expansion process, a new layout with a turbo-expander has been proposed for the natural gas liquefaction. The carried-out simulations show that the new proposed solution allow to optimize the LNG production process and to minimize the process' energy consumption

Integration of μ-SOFC Generator and ZEBRA Batteries for Domestic Application and Comparison with other μ-CHP Technologies

Abstract This study investigates the possibility to integrate a Solide Oxide Fuel Cell (SOFC) prime mover and ZEBRA batteries, with the aim to fulfill a domestic user energy demand and to reduce the primary energy consumption, thereby, to enhance the total efficiency in a μ-CHP (Combined Heat and Power) application on a yearly basis. A realistic operational sequence of the SOFC-ZEBRA integration has been calculated using simple logic conditions. Both electric and thermal integration have been considered, in order to exploit the SOFC residual heat for the battery stand-by feeding. The key advantage of this system architecture is that the SOFC is operated without major load variations close to constant load, resulting in longer lifetime and thus reducing total costs of operation. Eventually, a comparison with alternative μ-CHP technologies has been carried out, highlighting the SOFC-ZEBRA potential

Pump Hydro Storage and Gas Turbines Technologies Combined to Handle Wind Variability: Optimal Hydro Solution for an Italian Case Study☆

Abstract Load and wind energy profiles are totally uncorrelated, therein lies the problem of variable energy sources. Managing load with increasing wind penetration may call for operational ranges that conventional systems cannot readily access. Storage technologies could allow tolerating the unsteadiness of renewable sources with smaller fossil fuel plants capacity. Pumped Hydro Storage (PHS) is a crucial technology for balancing large steam power plants and may become increasingly important for storing renewable energies. Hence capacity ranges of PHS as well as its dynamic response to renewable power variability, will become progressively relevant. An integrated system made of a wind farm, a PHS plant and a set of gas turbines (GTs), as programmable fossil fuel devices, to handle renewable variability and maximize renewable energy exploitation, is studied in this paper. A specific case study is analyzed: a wind farm with a nameplate capacity equal to that installed in Sardinia is considered. To match the power output requested by the region with the integrated systems different configurations of PHS plant will be investigated. The impact of reversible or separate Francis machines with constant or variable speed will be analyzed in order to minimize electric power output overproduction and GTs fuel consumptions. Minimum and maximum capacity range for reversible or separate machines will be considered. The aim of the study is the optimum sizing and design of a PHS unit in a hybrid wind-hydro-gas turbine power plant to match the load request. Results in terms of PHS operation, water height behavior in upper and lower reservoirs, GT units power output, natural gas consumed and electric power output overproduction will be presented for each analyzed case

Thermodynamic Evaluation of Repowering Options for a Small-size Combined Cycle with Concentrating Solar Power Technology☆

Abstract The increasing penetration of low-carbon technologies and enhancements in fossil-fuelled power plants efficiency are some of the most important and up to date research topics. Renewable energy, in particular solar, has the potential of meeting the world energy needs while addressing environmental concerns, but technological advances in renewable energy electricity production are necessary to become competitive with conventional technologies. New opportunities to increase the penetration of renewables energies, smoothing out renewables variability and intermittency problems, come out from the hybridization concept. Hybrid renewable-fossil fuel systems join the advantages of both renewable energies and programmable devices. Among all the renewable technologies available for hybridization, Concentrating Solar Power (CSP) with parabolic trough is the most diffused because of its relatively conventional technology and ease of scale-up. CSP hybrids are well established worldwide, predominantly with natural gas: the hybridization options for CSP ranging from feed water heating, reheat steam, live steam to steam superheating. Based on a detailed thermodynamic cycle model of a reference small-size one pressure level Combined Cycle (CC) plant, the impact of CSP addition is thoroughly evaluated. Different hybrid schemes are evaluated and compared considering CC off-design operation. The goal of this study is to evaluate, from a thermodynamic point of view, three repowering options of a small-size CC with a CSP system in a hybrid system configuration and to quantify their potential benefits in terms of system's performance increase. In particular, the optimal size of CSP plant is shown for each investigated hybrid repowering options. The changes in CC steam cycle operating parameters are presented together with CC performance increase. It is shown that solar hybridization into an existing CC plant may give rise to a substantial benefit from a thermodynamic point of view