Electric propulsion is the object of intense research efforts all over the world, as a viable solution to fossil resource exploitation and pollutant emissions, towards a sustainable development. In this paper, we perform a thorough Life Cycle Assessment (LCA) of multiple electrical solutions for urban mobility, from bicycles to buses, comparing the results to those of traditional, fossil-fuel-based vehicles. This activity is of particular interest as the decision of European Parliament to interrupt the fossil fuel vehicles starting from 2035. To assess the life-cycle impact of each solution, several routes within middle size Italian cities, representative of the most Italian cities have been considered. This analysis has been performed by means of an ad-hoc integrated procedure with on-line, free tools that account also for traffic distribution. To carry out a complete study, an LCA analysis has been done which includes all life’s phase of the vehicles, starting from production to disposal.

As the emission regulations get more and more stringent in the different fields of energy and environmental systems, the electric and fuel cell vehicles (FCV) have attracted growing attention by automakers, governments, and customers. Research and development efforts have been focused on devising novel concepts, low-cost systems, and reliable electric/fuel cell powertrain. In fact, electric and fuel cell vehicles coupled with low-carbon electricity sources offer the potential for reducing greenhouse gas emissions and exposure to tailpipe emissions from personal transportation. In particular, Pedal Assisted Bicycles (PAB) popularity is rising in urban areas due to their low energy consumption and environmental impact. In fact, when electrically moved, they are zero emission vehicles with very low noise emissions, as well. These positive characteristics could be even improved by coupling a PAB with a fuel cell based power generation system, thus increasing the vehicle autonomy without influencing their emissions and consumption performances. In this paper, four types of vehicles are compared from an environmental and accessibility point of view: conventional car, bus, electric PAB and hydrogen fuel cell PAB; for such vehicles, the respective utilization stages are accounted for, i.e. without considering the manufacturing process. The analysis has been carried out comparing different vehicles performance along different routes of an Italian middle-size city, Viterbo, which represents a very good pilot case as its Municipality is adopting many solutions suggested by European Union (EU) through the planning tool called Sustainable Energy Action Plan (SEAP). The comparison is based on an ad-hoc developed mathematical procedure, which includes environmental (greenhouse gas and air pollution emissions), health (pollutants toxicity levels) and accessibility time (waiting times) indicators. According to this analysis, electric and fuel cell PAB exhibit interesting advantages over the other vehicles. However, the global economic efficiency of electric or fuel cell apparatus depends substantially on the exploited source of electrical energy.

In this paper, the results of three generations of reactors for the direct conversion of the Organic Fraction of Municipal Solid Waste (OFMSW) in electrical energy are presented. The different generations corresponds to the prototype realized in the Energy Lab of the University of Naples “Parthenope” and have been monitored along a period of over three years in terms of polarization and power curves, in order to assess the feasibility of Microbial Fuel Cell as a promising source for future, sustainable energy generation.

Effective energy storage technologies represent one of the key elements to solving the growing challenges of electrical energy supply of the 21st century. Several energy storage systems are available, from ones that are technologically mature to others still at a research stage. Each technology has its inherent limitations that make its use economically or practically feasible only for specific applications. The present paper aims at integrating hydrogen generation into compressed air energy storage systems to avoid natural gas combustion or thermal energy storage. A proper design of such a hybrid storage system could provide high roundtrip efficiencies together with enhanced flexibility thanks to the possibility of providing additional energy outputs (heat, cooling, and hydrogen as a fuel), in a distributed energy storage framework. Such a system could be directly connected to the power grid at the distribution level to reduce power and energy intermittence problems related to renewable energy generation. Similarly, it could be located close to the user (e.g., office buildings, commercial centers, industrial plants, hospitals, etc.). Finally, it could be integrated in decentralized energy generation systems to reduce the peak electricity demand charges and energy costs, to increase power generation efficiency, to enhance the security of electrical energy supply, and to facilitate the market penetration of small renewable energy systems. Different configurations have been investigated (simple hybrid storage system, regenerate system, multistage system) demonstrating the compressed air and hydrogen storage systems effectiveness in improving energy source flexibility and efficiency, and possibly in reducing the costs of energy supply. Round-trip efficiency up to 65% can be easily reached. The analysis is conducted through a mixed theoretical-numerical approach, which allows the definition of the most relevant physical parameters affecting the system performance.

Distributed generation, despite not being a new concept, is assuming a leading role in the field of energy conversion, as it should contribute to the enhancement of efficiency, flexibility, and reliability of national energy systems. However, it also noted that the effective performances of small and flexible power plants is critically influenced by their actual control strategy. Moreover, it is not trivial to identify a univocal parameter to evaluate the plant performance. For instance, cost evaluation clearly responds to an industrial view of the energy supply problem, while energy consumption or polluting emissions comply with a socio economic approach. In this scenario, the optimization of the plant management is a valuable instrument to gain insight on their behavior as the control strategy is varied, as well as to promote the distributed generation development, by maximizing the plants performances. In this paper, we further develop a graph based optimization methodology to optimize the set-point of an internal combustion engine based plant used to satisfy a hospital energy load, under different seasonal load conditions (winter, summer, and transitional seasons) and energy prices. Specifically, in order to dissect the effects of the objective function selection, two different optimization criteria are considered, namely economical optimization and primary energy consumption minimization. In particular, we focus on the features of the prime mover (i.e., the internal combustion engine) control strategy and on its drivers, as a function of the prescribed objective function. Results demonstrate that in the actual Italian energy market, cost minimization does not match primary energy consumption minimization, because the latter is only influenced by energy demand time series, and equipments performance, while the former is fundamentally driven by the electricity prices time series.

An effective methodology to determine the optimal operational strategy for a complex CHCP plant is presented. The model is based on the minimization of a chosen variable and it is organically developed integrating thermodynamics and economics. The graph-based optimization algorithm is developed in order to find the optimal set-points of the energy system components in a sufficiently short-time. By this way the model is applicable to real industrial problems, especially when the energy is sold to the electricity market. The problem in study is discretized in time and plant states, represented as weighted graph, and the strategy that minimizes the total cost is determined using backward dynamic programming. The proposed methodology has been applied to the optimization of the set-point of an internal combustion engine based plant used to satisfy an hospital energy load, under different seasonal load conditions (winter, summer and transitional seasons) and energy prices. Two different optimization criteria are considered, namely economical optimization and primary energy consumption minimization. It is then demonstrated that the model can be effectively applied to analyze the cost and profit in energy conversion in power plants, related to electricity price, fuel price, running of turbine and auxiliary equipment, service power consumption. In particular; the chosen test case demonstrates not only the model reliability but also the economical and thermodynamic convenience of using the model itself to optimize the plant.

Safety, security, and sustainability of energy supply chains are among the main concerns of industrialized countries, and, therefore, distributed generation has significantly increased its share of the energy market, thanks to the possibility to simultaneously meet electrical, thermal and cooling demand, thus increasing the overall source-to-final-use conversion efficiency. The efficiency of a distributed generation system is influenced both by the individual performance of the plant components as well as by their interconnection, and is very sensitive to the control strategy adopted in the different plant sections. This last remark is particularly relevant for distributed generation systems, that are subject to rapid gradients in both the thermal and electrical loads, and in the values of the energy vector. In this respect, the introduction and the correct management of energy storage systems is a key point for trigeneration plants. In fact, energy storage brings on the one side advantages as for the reduced components sizes, but more importantly allows for a substantial decoupling of the thermal and electrical demands, making load following less of a stringent requirement. An optimization methodology, based on energy fluxes simulation, and on the application of the graph theory as in previous works by some of the authors, is used to identify the optimal set-points for each component. The optimization algorithm searches for the plant management envelope that minimizes a prescribed objective function. Specifically, two different optimization criteria are considered: i) economic optimization that minimizes the total daily operating cost and ii) primary energy use optimization, that minimizes the total daily amount of primary energy used by the plant. Since the paper focus is on the effects of energy storage, the trigeneration plant behavior will be analyzed both in terms of economical results and in terms of efficiency and primary energy use.

In this paper we introduce an enhanced methodology to determine the optimal control strategy for a complex trigeneration plant. The plant is designed to meet the thermal and electrical loads of a user and is connected to the electrical grid. We consider a single working-day and the plant set-points are determined on an hourly basis minimizing total energy cost, plant maintenance costs, and costs associated to switching on and off the power plant components. To realistically simulate the behavior of large power plants, a constraint on the minimum duration of on and off intervals is considered for each plant section.The problem in study is discretized in time and plant states, represented as weighted graph, and the strategy that minimizes the total cost is determined using backward dynamic programming, whose computational effort is compatible with real practical applications.Validity and usefulness of the proposed methodology are demonstrated optimizing the set-point of a combined heat, power and cooling system, under different seasonal load conditions and energy prices. We demonstrate that an optimized strategy would reduce the total daily cost from 8% to about 100%, depending on seasonal load, with respect to rule based control strategies, such as heat-tracking and electrical tracking. Crown Copyright (C) 2014 Published by Elsevier Ltd. All rights reserved.

In the last decade, the service sector had a very rapid growth, due to the so-called “tertiarisation” of the economy. Accordingly, the energy consumption, mainly attributable to public and private buildings, is rapidly growing, thus making buildings energy saving one of the main issues of the energy policy at regional, national and international levels. To this aim, we developed an effective methodology to improve energy efficiency of the service sector buildings. This may represent a handy great opportunity to save natural and economic resources, especially where the buildings structure and the technical systems are old, the maintenance activities are not carefully carried out or a systematic energy management is not applied. Nevertheless, actions in this direction are often considered too expensive and complicated, if compared with residential energy optimization, because of the big extension, the variety of activities and the high number of occupants typical of the service sector buildings. The developed approach for energy audits aims to investigate the energy aspects of existing non-domestic buildings in a structured way, in order to clearly identify their energy saving potential and to improve their energy performances. The main goal of the study is defining a general methodology to analyze the current energy use and consumption considering a limited number of their peculiar elements such as dimensions, activities, users behavior, technical systems data and energy bills. Furthermore, these informations are completed by an appropriate energy measuring campaign. All the possible energy uses in service buildings are taken into account (i.e. lighting, ventilation, air conditioning, hot water production). The results obtained from the analysis allow to evaluate a global level of building energy efficiency, and to identify those single areas, specific systems or everyday activities where energy is wasted. These considerations also provide basis for programming cost-effective energy saving action plans. The effectiveness of the proposed methodology is demonstrated through a case study for an Administrative Center building in Rome, Italy. Results demonstrate the methodology reliability and the cost reduction potentialities.

The rising energy costs, the growing concern about globalcompetition and environmental issues and theapproaching exhaustion of world energy resources areurging national governments and industrial companies toimprove energy management.

Methodology Development for a Comprehensive and Cost-Effective Energy Management in Industrial Plants 17 control system is proposed.The methodology supports to identify maintenance condition through energy consumption characterization, predicting and control (Cesarotti et al., 2010).In (Sarimveis et al., 2003) an example of power systems management optimization through mathematical programming tools is presented.In other terms, the availability of optimization tools for the energy plant operation (i.e. the possibility of optimally determining when boilers, turbines, chillers or other types of machinery shall be set on or off or partialized) may lead to energetic, economic and environmental savings.In scientific literature, several criteria for the optimization of combined cooling, heating and power systems in industrial plants are available based on different management hypotheses and objective functions.The goal of the models is to optimize the operation of the energy system to maximize the return on invested capital.Many of these models do account for load operations but use simple linear relationships to describe thermodynamic and heat transfer process that can be inherently non-linear.In (Arivalgan et al., 2000) a mixed-integer linear programming model to optimize the operation of a paper mill is presented.It is demonstrated that the model provides the methods for determining the optimal strategy that minimize the overall cost of energy for the process industry.In (Von Spakovsky et al., 1995) the authors use a mixed integer linear programming approach which balances the competing costs of operation and minimizes these costs subject to the operational constraints placed on the system.The main issue of the model is the capability to predict the best operating strategy for any given day.Nevertheless, the model validity is strictly dependent on the linear behaviour of the plant components.In (Frangopoulos et al., 1996) the authors have employed linear programming techniques to develop an optimization procedure of the energy system supported by a thermoeconomic analysis of the system and modelling of the main components performance.In (Puttgen & MacGregor, 1996) a linear programming based model maximizing the total revenue subject to constraints due to conservation of mass, thermal storage restrictions and shiftable loads requirement is developed.Finally, thermoeconomics offers the most comprehensive theoretical approach to the analysis of energy systems where costs are concerned.It is based on the assumption that exergy is the only rational basis to assign cost.In other terms, the main issue is that costs occur and are directly related to the irreversibility taking place within each component.Accordingly thermoeconomics could represent a reliable approach to the optimisation of energy plants operation involving thermodynamic and economical aspects (Tstsaronis & Winhold, 1985), (Temir & Bilge, 2004), (Tstsaronis & Pisa, 1994).However, these studies have paid little attention in integrating the different individual energy management functions into one overall system.From this point of view, in this chapter we provide a comprehensive integrated methodology for implementing an automated energy management in an industrial plant.

The application of high temperature fuel cells in stationary power generation seems to be one of the possible solutions to the problem related to the environment preservation and to the growing interest for distributed electric power generation. Great expectations have been placed on both simple and hybrid fuel cell plants, thus making necessary the evolution of analysis strategies to evaluate thermodynamic performance, design improvements and acceleration of new developments. This paper investigates the thermodynamic potential of combining traditional internal combustion energy systems (i.e. gas turbine and internal combustion engine) with a Molten Carbonate Fuel Cell (MCFC) for medium and low-scale electrical power production with low CO2 emissions. The coupling is performed by placing the fuel cell at the exhaust of the thermal engine. As in MCFCs the oxygen-charge carrier in the electrolyte is the carbonate ion, part of the CO2 in the gas turbine flue gas is moved to the anode and then separated by steam condensation. Plant performance are evaluated in function of different parameters to identify optimal solutions. The results show that the proposed power system can be conveniently used as a source of power generation.

As a consequence of the increasing importance of environmental issues, natural gas has emerged as one of the most promising energy sources for internal combustion engines, in the short medium term, because its usage leads to cleaner combustion, lower CO2 emissions, and energy source diversification. However, considering that automotive DI gas engines are rather new, only limited experience exists on the optimum configuration of the injection system and the related strategy. To facilitate the development of these applications, computer models are being developed.In a previous paper, a phenomenological-3-D integrated approach to simulate gas injection has been presented and validated. This model has been implemented in a modified version of the KIVA 3V code. In this paper the model is used to perform the analysis of an impinging gas jet. The interaction between impinging jet and airflow plays a fundamental role in mixture formation and thus on the evolution of combustion process and pollutant formation. This is particularly true if considering stratified charge engine with late cycle injection. In this paper three wall jet treatments are considered: two different laws of the wall and a no-slip simulation in order to evaluate their feasibility in capturing the jet evolution. Numerical results are validated by comparison against experimental data found in literature. (c) 2010 Elsevier Inc. All rights reserved.

The use of natural gas (instead of liquid or solid fuels) is nowadays drawing an increasing interest in many applications (gas turbines, boilers, internal combustion engines), because of the greater attention to environmental issues. To facilitate the development of these applications, computer models are being developed to simulate gaseous injection, air entrainment and the ensuing combustion.This paper introduces a new method for modelling the injection process of gaseous fuels that aims to hold down grid requirements in order to allow the simulation also of other phenomena, like combustion or valve and piston motion, in reciprocating internal combustion engines. After a short overview of existing models, the transient jet model and the evaluation of inflow conditions are described in detail. Then a basic study of the grid effects on the jet evolution is presented. The model is updated and validated by comparing numerical results with available experimental data for two different operating conditions: a subsonic and a supersonic under-expanded case. The model demonstrates to be fast enough to be used in a multi-dimensional code and accurate enough to follow the real gas jet evolution. Copyright (C) 2009 John Wiley & Sons, Ltd.

Direct injection of gaseous fuel has emerged to be a high potential strategy to tackle both environmental and fuel economy requirements. However, since the electronic gaseous injection technology is rather new for automotive applications, limited experience exists on the optimum configuration of the injection system and the combustion chamber. To facilitate the development of these applications computer models are being developed to simulate gaseous injection, air entrainment, and the ensuing combustion. This paper introduces a new method for modeling the injection process of gaseous fuels in multidimensional simulations. The proposed model allows holding down grid requirements, thus, making it compatible with the three-dimensional simulation of an internal combustion engine.

The increasing energy demand along with the growing concern for environmental issues make energy saving one of the main tasks of present times and it is likely to become even more important in the next decades, as the economic growth is being pursued in developing countries, as China, India and Brazil. As a consequence, researchers, industries and politicians are required to make significant efforts in this field. More and more stringent regulations on pollution and CO2 emissions have been issued, which means limiting energy consumption. However, even if policy is an important tool, it cannot be the only one and it is necessary to spread the knowledge on energy systems, energy saving options and energy use rationalisation (Lopes et al., 2005). This is a prerequisite to make right choices for a more efficient use of energy, even if these choices are not mandatory from a “legal” point of view. Being obvious that this knowledge should be transferred to all the population layers, it is important that the main energy users, as industry, realize that energy is not merely an overhead, as part of business maintenance, but actually a raw material resource required to run the business. Energy management programs should, therefore, become an integral part of the corporate strategy, to increase the business’ profitability and competitiveness. Moreover, knocking down energy costs most of the times means reducing demand on the world’s finite energy sources, cutting pollution and creating a healthier working environment. The main example in this context is Japan, as the Japanese economy is the most energy efficient in the industrialized world and their improvements in energy efficiency enabled the Japanese industry to increase its output of 40% by spending the same energy in 2001 as in 1973 (Van Schijndel., 2002; Kamal, 1997). In general, the application of good energy management practices and energy-efficient equipment allow a readily achievable, costeffective, 20% reduction in industrial consumption (Smith et al., 2007) Energy saving can be realised through different actions on both the utilisation and the production sides (Agency for Natural Resources and Energy, 2004; Meier, 1997). However, it is really a complex task, as many factors influence energy usage, conversion and consumption and these factors are strictly connected to each other. For example, when 9