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Abstract The combined production of electricity, heat and cold by a polygeneration system connected to a district heating and cooling network can provide high energy utilization efficiency. The inherent complexity of simultaneous production of different services and the high variability in the energy demand make combined cooling and heating systems performance highly dependent on the operational strategy. In this paper, an operational optimization method based on the moving average of real-time measurements of energy demands and ambient conditions is proposed. Real energy demand data from a district heating and cooling network close to Barcelona, Spain, are used to test the method. A complex polygeneration system is considered, consisting of an internal combustion engine, a double-effect absorption chiller, an electric chiller, a boiler and a cooling tower. A detailed modelling of the system is provided, considering partial load behavior of the components and ambient conditions effects. Results of the real-time optimal management are discussed and compared to traditional operational strategies and to the ideal optimal management achievable with perfectly accurate forecast of energy demands. Moreover, the optimal width of the window adopted for the moving average of real-time data is identified.

Abstract The 21st Conference of the Parties (COP21) of the United Nations Framework Convention on Climate Change (UNFCCC) marked a milestone in the course of international efforts on global climate action. As part of the COP21 side events, on December 4th the Lima Paris Action Agenda presented a half-day of presentations and round table discussions titled Focus on Private Finance. The event was supported by the Secretary-General of the United Nation, Caisse des Depots, and the I4CE Institute for Climate Economics. This conference report summarizes the findings of the session and the messages delivered by finance industry representatives. Significant investment in low carbon assets is required to maintain global temperature increases below 2 °C. The two resounding themes throughout the session were that in order to attract capital for low carbon investments fossil fuel subsidies must end and a higher carbon price is needed to incentivise investment. Furthermore, accounting and regulatory bodies need to implement more stringent disclosure and reporting requirements so that climate risk is properly understood by investors. There is significant appetite for investment in the low carbon sector which is demonstrated by the growth in the green bond market. Financial institutions have a role to play in aggregating, structuring and de-risking investments to facilitate private finance investment. Policy makers also need to improve the investment environment by creating consistent and stable long term policies which will give investors' confidence.

Abstract The sustainable indicators are characterized by a low degree of aggregation and a high amount of information. An indicator must show a synthetic representation of a real environmental, by using a value or a parameter, so that they can be easily used by policy makers. It is necessary to connect, therefore, the various systems in an appropriately integrated sustainable system. The indicators need to be aggregated based on the structure of the data. Each indicator must to be defined through a weight with reference to another weighted indicator. In this paper is illustrated the calculation of the assigned weights that uses a procedure based on fuzzy logic and to define a model that allows us to estimate the sustainability of a city. The final result is, therefore, a combination of values assigned by expert opinion for the various criteria, processed using fuzzy logic to obtain a weight with significant objectivity and as it is possible to estimate the sustainability of the city through the weights.

This paper presents results of an online stated choice experiment on preferences of Dutch private car owners for alternative fuel vehicles (AFVs) and their characteristics. Results show that negative preferences for alternative fuel vehicles are large, especially for the electric and fuel cell car, mostly as a result of their limited driving range and considerable refueling times. Preference for AFVs increases considerably with improvements on driving range, refueling time and fuel availability. Negative AFV preferences remain, however, also with substantial improvements in AFV characteristics; the remaining willingness to accept is on average € 10,000-€ 20,000 per AFV. Results from a mixed logit model show that consumer preferences for AFVs and AFV characteristics are heterogeneous to a large extent, in particular for the electric car, additional detour time and fuel time for the electric and fuel cell car. An interaction model reveals that annual mileage is by far the most important factor that determines heterogeneity in preferences for the electric and fuel cell car. When annual mileage increases, the preference for electric and fuel cell cars decreases substantially, whilst the willingness to pay for driving range increases substantially. Other variables such as using the car for holidays abroad and the daily commute also appear to be relevant for car choice. © 2014 Elsevier Ltd.

Abstract District heating dynamic models arise as an alternative approach to in-situ experimental investigations. The main advantage of dynamic modeling and simulation is the possibility to avoid technical and operational risks that might occur during in-situ experimental investigations (e.g. heat demand is not met, damages in the energy systems etc.). Within this study, the authors present two models for an existing district heating system in Cottbus, Germany. One model is developed using the tool EBSILON Professional, while the other one is developed using the Simscape toolbox for physical modeling in Matlab/Simulink. The models were experimentally validated against measured data from the considered district heating system. The results show that the Simscape model has a better fit and better response than the EBSILON model. Yet, some discrepancies were found between the measured and the simulated data and, therefore, the uncertainties of the models were addressed. A comparative study between both tools is presented. The EBSILON models permit only unidirectional flow, whereas the Simscape toolbox permits reverse flow. Nevertheless, the EBSILON model outperforms the Simscape model in computation time. In addition, this study presents an approach for dynamic thermo-hydraulic modeling of district heating networks. This approach is utilized to examine the role of district heating networks as heat storage as an optimization configuration. The numerical results show less start-ups for additional heat sources. Yet, higher heat losses from the network are observed due to the installation of unburied pipelines.

Abstract The cathodic electrodeposition of paint on metals proceeds under the influence of an alkalization of the diffusion layer, which is caused by the cathodic reduction of water to yield hydrogen. Three independent electrochemical methods, namely the rotating cone electrode at constant current density, chronopotentiometry and cyclic voltammetry, both at stationary electrodes in stagnant electrolytes, were employed to study the influence of cathodic corrosion of aluminium. It generates initially aluminate as a corrosion product. It was found that the tendency for electrocoagulation is strongly enhanced at Al surfaces in comparison to steel. This is attributed to a higher efficiency due to the in situ formation of intensively dispersed aluminium-oxidhydrate through hydrolysis of the aluminate anions. Thus, the electrocoagulation process is not only an acid/base-reaction with the macro-ions: p - NR 2 H + + A 1 O 2 − → p - NR 2 ↓ + AlOOH ↓, but the presence of AlOOH nuclei improves the formation of a new polymer phase.

Abstract This paper investigates two transition initiatives at the local level – namely the reconversion of the Porto Marghera and Gela refineries into biorefineries for second-generation biofuels. The study aimed at assessing the extent to which the narrative pressures exerted by local actors influenced the perspectives of key stakeholders involved in these transition processes. To this end, a blended methodology was employed, combining discourse analysis with stakeholder analysis and semi-structured interviews. First, stakeholders were grouped into four categories according to the source (national/global) and channel (formal/informal) of pressure. National/informal actors emerged as the most influential group. The discourse analysis identified three dominant storylines representing complementary trajectories defined by national actors operating through informal channels. Finally, semi-structured interviews with key local actors involved in the Porto Marghera and Gela reconversions were used to assess the impact of these storylines in the reconversion processes. Comparison of the two cases revealed fundamental specificities related to their respective cultural, political and socio-economic contexts. While the Porto Marghera reconversion was presented as a consolidated success story (albeit with a number of drawbacks related to the fact that it was still mainly powered by first-generation feedstocks), the Gela case was viewed as a complex and challenging ongoing process with an uncertain outcome.

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