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With the rapid development of electronic technology, the use of portable and wearable electronics hasbeen widely. In order to eliminate the dependency of low-power electronic devices on batteries and the associated requirement of periodic replacement, researchers have begun investigating methods of generating energy from ambient sources. An airflow energy harvester for human motion is typically composed of a spring-mass system with an air pump connected in parallel with a spring and a turbine. Recent studies have proposed some airflow energy harvesting devices. However, these studies are focused on structural design and little attention has been devoted to the energy conversion process. There are two processes for energy conversion: human motion to airflow energy, then airflow energy to electricity. Focus on the energy conversion, this paper proposes a way to evaluate the energy of the airflow from the perspective of damping at harmonic excitations. The model of an airflow energy harvester for human motion composed of a spring-mass system with an air pump connected in parallel with a spring and a turbine is built, and the balance force analysis is carried out. Comparing the mathematical models and the force analysis equations, the regular pattern of the damping change of the system during the vibration is defined. The simulation isperformed, the result indicates that the energy of the airflow which the vibration system provides is related to the damping of the system. This paper provides a new method toanalyzethe energy conversion process, which helps to measure the efficiency of the airflow energy harvester preferably.

Air pollution and increased CO2 concentration in atmosphere and other energy related issues caused a transformative shift in energy system which contributes to increased utilization of renewables as alternative to generate green energy carriers. The potential of renewable resources in different region and potential energy conversion have been largely considered by many researcher in many countries. The energy conversion technologies to produce heat, electricity, and transportation fuels have made impressive technical advances. Sweden has also been challenging with mitigation of CO2 emission and trying to shift into a fossil fuel free system in all energy sectors. This paper deals with the current status of fuel demand and supply in the transport sector in a County in Sweden. A scenario for a fossil fuel free transport sector at a regional level is developed to investigate the potential biofuel production from regionally produced straw. The results and analysis indicate that the potential for cereal based bioethanol production in the region is sufficient to meet the biofuel demand of the County. Using the fallow land for cereal cultivation, it is feasible to shift into a fossil fuel free transportation system where all passenger cars are fueled by bioethanol. The results and finding from the current paper will be used to develop further study on optimization of local biofuel production integrated with CHP plants considering application of other feedstock such as municipal wastes.

This paper constructed an energy configuration model with economic optimization in distributed energy system. On this basis, we carried out the sensitivity analysis of the price of large power grid, natural gas, cooling, heating and secondary power for the economic optimized results. And then, we have analyzed the critical value point of new energy conversion technologies appear or old disappear with the change of those energy price. In this paper, the secondary power price is same with the price of large power grid. In this study, an economic analysis of a distributed energy station project has been completed, which is a commercial complex in Shanghai. The results show that the power price have a biggest impact to -F value, and the influence of heating price is minimum, and supposing that self-generating electricity is grid-connected with no power injection. And at last, we find that the energy conversion technologies appear in different place of different scenario.

Energy is the blood of modern society and energy system plays an increasingly important role in urban development, especially in the background of a new round of energy reform. The construction of a new-generation of urban energy systems is becoming an important breakthrough to solve the bottleneck of urban development and to improve the quality of urban development in the future. From the perspective of the relationship between energy and cities, this paper analyzes the current situation and existing problems of urban energy system. Taking the research of energy system in Xiong’an New District as an opportunity, this paper explores the operation structure and implementation path of the new-generation urban energy system in Xiong’an New District. In this paper, it is considered that the new-generation energy system in Xiong’an New District will be electricity-centered, smart grid as the platform, energy transregional transmission combined with local development, optimal scheduling among multiple energy categories, and "source-grid-load-storage" high-efficiency interaction as well as the unified open market. The proposal of the new generation of urban energy system cannot only point out the direction for the planning and construction of the energy system in Xiong’an New District, but also help to solve the general problems in the urban energy system and promote the trend of energy transformation.

The integration of heat production from solar energy technologies can be realized by feeding in energy both at centralized or at multiple decentralized locations from the consumer side. As distribution networks serve as thermal transmission grids, the interaction between the energy feed in (i.e. production) and withdrawal (i.e. consumption) at multiple locations within distribution networks should be incorporated. Modelling the interactions between these subsystems is challenging. This paper aims to study the potential of district heating system with solar thermal based prosumers, by developing a modelling framework for design and simulation of such networks. Quantitative comparisons are made on the system performances, by addressing key technical configurations and constraints of thermal networks and temperature dynamics of energy sources. In this paper, a comprehensive design and simulation model is built to assess the performance of different scenarios of district heating system designs with solar thermal based prosumers. Design variations are carried out by selection of different buildings in the district as prosumers. The simulation model framework is setup in Matlab, with hourly time step. The distribution network model is formulated as a thermal hydraulic model representing detailed information on thermal and hydraulic losses on each pipe. It enables bidirectional flow from multiple sources integrated into the district heating network. Energy conversion technologies (solar thermal collectors) and heat demand are connected with the network model as source and sink. A natural gas boiler acts as an additional base load heat source. The design and simulation framework is applied to an artificial case study, composed of 20 buildings with mixed building stocks including office and residential buildings.

Electricity generation of renewable sources has got great development to reduce the usage of fossil fuels. Linear generator is a newly-developing orientation to utilize the power with reciprocating movement. In the paper, the structure and principle of the direct-driven linear generator (DLG) are introduced. The induction electromotive force is given in detailed based field & circuit method. Meanwhile, the paper introduces the design, fabrication and testing of a DLG prototype, theoretical model of the free-piston engine is presented, and the DLG operation driven by Simulated Power Source (SPS) is discussed. Furthermore, the performance of the system is investigated in detail under different conditions. The results show that, there is an optimal capacitance to get the highest coefficient, which is 25μF here. The frequency has obvious effect on the output at lower load resistance, but it has little effect on the efficiency, the efficiency depends more on the ratio of the load resistance and generator internal resistance. Lastly, according to the analysis results with the phasor algorithm analysis, the proposed model and analytical method are correct and effective. The DLG has a good application prospect in the energy conversion field.

The development of renewable energy is essential for relieving the pressure of increasing energy demand and reducing the greenhouse gas emission. The intermittency and uncertainty nature of renewable energy generation can lead to overproduction and consequently the curtailment of renewable energy. As the installed capacity of renewable energy increases, the curtailment problem is getting more serious. Thus it is of great significance to improve the integration of renewable energy from the perspective of economy and stability among various energy vectors. Power to gas (P2G) technology is a novel way to deal with the promotion of renewable energy integration, which can increase the coupling of electricity and gas by transforming extra renewable energy to storable hydrogen and methane. In this paper, the P2G technology is integrated to the multi-source microgrid (MSM), which includes wind power, electric boiler, micro turbine and gas boiler, and thermal storage, gas storage and electric energy storage are also included in the MSM. The MSM is modeled under the framework of energy hub, the optimal scheduling model of the MSM is based on the objective function of minimizing the total cost, consisting of energy cost of buying electricity and nature gas, as well as the penalty cost of wind power curtailment. A Monte Carlo simulation is used in this paper to analyze the uncertainty of wind power. The result of this paper shows that by optimizing the various energy flows and utilization of energy conversion, dispatch and storage technology in the MSM, the overall energy efficiency is significantly improved.

Thanks to various feed-in-tariff programs, aimed to the development of electric energy production from renewable sources, several biomass firing power plants have been realized in Italy in the last few years, contributing to the reduction of greenhouse gas emissions and fossil fuel energy dependence. In particular, during 2012 there was a rush for the completion of several renewable energy conversion power plants, leading up to 986 new plants to get the first connection to the grid (+81,3% with respect to 2011); among those, 80 new plants were solid biomass firing plants (+47,1% with respect to 2011) [1]. Linea Energia S.p.A., the Energy Business Unit of the multiutility company LGH, Linea Group Holding, which operates over the areas of Brescia, Cremona, Crema, Lodi and Pavia, gave its contribution in 2012 with the realization and start-up of two waste wood fueled energy conversion plants located in the Northern Italy, more exactly in Cremona and Rodengo Saiano (Brescia). This paper focuses on the operation and maintenance experience of the waste wood conversion power plant of Cremona, which is capable for a gross electric power production of up to 1.0 MW and a thermal power recovery of up to 5.5 MW. In the first part of this paper a description of the plant is presented, giving an insight of the engineered process. In the second part, the performance analysis of the energy conversion process is discussed by comparing actual performance of the system with the originally defined reference performance. In 2016, as a consequence of the operation of the unit in anomalous conditions (air entering in the system) the turbine blades got scaled. The output of the turbine progressively decreased but was then successfully re-established after an extraordinary maintenance carried out by the turbine supplier.

Smart energy systems are complex systems (i.e. composed of windmills, PV panels, solar collectors, heat pumps, CHP systems, etc) in which synergies rise through the ICT (Information and Communications Technology) based management and control of the whole system. In the development of efficient smart energy systems, a fundamental step is the optimization of total energy conversion, transmission and utilization processes within the whole system. To this extent, mathematical models can represent very useful tools for the simulation of the behavior of the system. In this paper, a library for the dynamic simulation of smart energy systems is presented. The library is implemented in Matlab ® /Simulink ® and each component (i.e. the energy conversion and distribution systems and the end-users) is developed through a modular approach. Therefore, the modules are designed by considering a standardized input/output and causality structure. Finally, the capabilities of this approach are evaluated through the application to the district heating and cooling network of the Campus of the University of Parma. The case study is based on a branch which feeds twelve buildings with a total heating volume of about 150 000 m 3 and peak thermal power demand of about 8 MW. Results reported in the paper demonstrate the effectiveness of this approach and the capability in term of system optimization.

At present, the accurate evaluation of the thermo-physical behaviour of multicomponent fluids represents a crucial element for studying and simulating low CO 2 emission energy conversion technologies. In order to extend the range of application of the available thermodynamic models, an intense experimental research activity has been performed in recent years. The main purpose of this paper is to describe the experimental and modelling procedures applied by the authors to measure and to analyse data extracted from the Vapour-Liquid Equilibrium apparatus recently installed at LEAP laboratory. This test rig allows the characterization of mixture phase equilibrium properties on the basis of the static-analytical method, within the pressure and temperature ranges of 0 – 20 MPa and -60 – 200 C. Finally, the paper reports the most relevant features and the main guidelines for the instruments calibration procedures.

In this paper, the possibilities and conditions for CCS applications in Finland are assessed. The study includes an overview of Finland's current climate and energy policy framework, mapping of large CO2 emission point sources and identification of possible CO2 transportation and storage alternatives. The future role of CCS in the Finnish energy system is further assessed with energy and emission scenarios created with a comprehensive model called TIMES-Nordic. There are several large CO2 emission sources in Finland that could be potential candidates for CCS, including steel works, power and heat generating plants, as well as oil refineries. In 2008, the 12 largest facilities in the Finnish emission trading registry accounted for 30% of the total CO2 emissions in Finland. Since the Finnish bedrock is not suitable for large-scale geological storage of CO2, captured CO2 would most likely have to be transported to the North Sea or Barents Sea for long-term storage. Most of the largest CO2 emitting facilities are located on the coast line of Finland, which facilitates transportation of CO2 by ship. The current Finnish climate and energy policy largely focuses on increasing the share of renewable energy and nuclear power in energy conversion, which leaves less room for CCS. The preliminary results from the scenario calculations indicate that the share of CO2 mitigation by CCS in Finland would be less than 10 Mt/a CO2 by 2050. However, Finland has also large, stationary CO2 emissions originating from biomass combustion in the pulp and paper industry. When assuming that biogenic CO2 emissions would be included into the emission trading system, the CCS potential rises up to 18 Mt/a CO2 by 2050.

With the economic development, the demond for energy is growing in China, and the traditional non-renewable energy makes the energy transformation is imminent.In this paper, based on the fully understanding of our existing energy structure, and from the perspective of supply and demand, the author analysis the changes in the structure of future energy and gives the suggestion.The paper argues that China's energy structure will gradually turn to be comprehensive and diverse, but the cost and market constraints will obstruct the promotion of renewable energy sources.Therefore, the traditional high-carbon energy is still the main form of domestic energy consumptionin a very long period of time.Only by improving technology and using of the macro-control can reduce the costs and regulate the import and export, which can achieve sustainable development of changing from a high-carbon energy to low carbon.

The paper presents a different approach on biomass combustion process modelling based on Bond Graph methodology. The main thermal-chemical processes used for biomass to energy conversion are oxidative. This study focused on oxidation process with heat generation using solid fuels. The important number of biomass categories and different conversion technologies influence the model input parameters in terms of temperatures, mass flows, heat exchange, requiring different models for combustion processes. The large range of biomass based products can be represented by carbon, hydrogen, oxygen, chlorine, sulphur, and nitrogen composition. In order to highlight the modelling method advantages, the research focused on wood biomass combustion. The product was represented by carbon, hydrogen, and oxygen composition given through their molar fraction. The paper presents the results on combustion process kinetics with respect to reactant and reactor input data, especially for the transitory regimes like ignition. The model provides information on time variation of the heat of reaction, reaction products concentration, and reactants concentration / accumulation, based on global mass and energy balance of the process.

As the further development of regional integrated multi-energy microgrid, the management of microgrid operators is getting more difficult because of different interest parts and data privacy preservation. Thus, an ADMM-based multiperiod optimal energy flow (MOEF) model is presented in this paper, which is meaningful to research collaborative operation scheduling of multi-energy microgrid. Since the MOEF model considering constraints of multi-energy networks and energy conversion units are highly nonlinear and nonconvex, a second-order cone relaxation and incremental linearization method are adopted to mathematically transform it into a solvable mixed integer second-order cone programming (MI-SOCP). A modified regional integrated multi-energy microgrid case is evaluated to demonstrate the effectiveness of the proposed model and method.

Proton exchange membrane fuel cell (PEMFC) has been recognized as the most promising energy conversion device due to its outstanding merits, such as high energy efficiency, low pollution, low operating temperature and low noise. Due to the complicated process of water production and transportation in porous media, the water concentration can affect the distribution of species and ionic conductivity, thus, the water management has been regarded as one of the most critical issues for PEMFC. In this paper, a three dimensional multiphase non-isothermal model for the PEMFC performance prediction has been developed to study the effect of ionomer volume fraction on the performance of PEMFC. The numerical results show that the ionomer volume fraction of catalyst layer has an appreciable effect on the performance of PEMFC and water distribution in porous electrodes, the higher ionomer volume fraction in catalyst layer can be helpful to avoid the flooding problem in porous electrodes.

This paper addresses from both macro- and micro- areal coverage in introducing hydrogen system in terms of cost and performance, where the produced hydrogen from surplus photovoltaic (PV) power is stored. Feed-in tariff in Japan had successful achievement for great expansion of renewable energy systems (RES), causing problematic operation due to excess power by overcapacity of RES. One of the candidate approaches to overcome this surplus energy by RES is Power to gas (P2G) system, using electrolysis cells (ECs), fuel cells (FCs) or co-firing in gas turbines, both for energy conversion as well as power balancing. Numerous studies had been investigated on P2G however, within our knowledge no study had been addressed the system from both coverages with different capacity and scales. We investigate micro level (zero emission building in our university) and macro level (Kyushu, one of big regions in Japan). We describe for macro side preliminary result on economic analysis of using surplus power of RES via production and storage of hydrogen while for micro side research design.

The previous works on the use of PEM Fuel Cell based power supply system for the operation of off-grid RBS (Radio Base Stations) sites showed a strong influence of system design parameters on the energy conversion performance. In this paper a perturbation of system design is performed through validated models to understand better the variability of performance over a full year operation. Results show that a ratio of energy produced by fossil over energy produced by renewables sources of 0.2 can be reached slightly increasing the photovoltaic plant size without affecting drastically the renewable exploitation. Moreover a positive Net Present Value can be achieved in comparison with the traditional diesel genset solution (from 260k€ to 350k€). The NPV value increases with the PV size and with a reduction of the battery size that leads to a steep reduction in the RES exploitation. Therefore, an optimum has to be sought as a compromise between the two aspects.

Recently, the concept of integrated energy distribution system (IEDS) has gained popularity both in academia and industry, it is characterized by the comprehensive integration of multi-energy carriers and flexible utilization of available resources including distribution generations (DGs). However, the stability problem caused by the intermittency of renewable energy and uncertainties of energy demands are among the main concerns that need to be regulated properly. To address this issue, a novel method of tie-line power optimization is proposed in this paper, where the synergies among various energy sectors are stressed. The model of regional energy station (RES) is studied to provide the model basis, which can be regarded as the coupling link of electric power system (EPS) and natural gas system (NGS). In this regard, the flexibility of energy conversion and dispatch can be utilized as a kind of controllable resources for the sake of tie-line power optimization. Therefore, the tie-line power can be regulated in a flexible way in response to the control signal from the dispatch center. Verified by numerical studies, the results show the efficiency and applicability of the proposed strategy.

Nowadays the global demand for energy is growing rapidly in China, which will be the world’s largest country of energy consumption, it is thus highly urgent to conduct the research and development of efficient renewable wave energy equipment, e.g. wave energy converter (WEC). So, this paper aims to numerically develop a new WEC suitable for wave conditions in Zhoushan sea area. The specific research contents include the following aspects: (1) theoretic design by using the floating pendulum to capture the wave energy; (2) Computational Fluid Dynamics (CFD) simulation which is based on 3-Dimensional unsteady Reynolds Average Navier-Storkes (RANS) equations to analyze the hydrodynamic performance of floating pendulor capturing wave energy. The initial design has been optimized to find the parameters of swing device floating in different output loads of energy capture, and to recognize the conditions of the device for subsequent energy conversion system design.

Improving the efficiency of organic Rankine cycle (ORC) is the ultimate goal of the researchers with thermodynamic background. As the “blood” of ORC, the working fluid plays a vital role to the improvement of the performance. The thermos-physical properties parameters, transport parameters and other parameters of working fluids could directly affect the efficiency, safety, stability and economy of ORC. With the increasing requirements on working fluids, it is difficult to find a pure working fluid not only with satisfied thermodynamic performance but also permissible enverimental protection and safety. In contrast, zeotropic working fluid, which is mixed with two or more pure working fluids, is easier to meet the requirements of thermos-physical properties, environmental and safety. But at the present stage, the application of zeotropic working fluids in ORC still adapted or employed the methodology originated from what we learn from pure working fluids. Under such circumstances, the temperature glide of zeotropic working fluids improves system efficiency while the composition shift would in turn reduce system efficiency. Thus, 3D-ORC is proposed in this paper to provide zeotropic working fluids a full play on performance improvement of energy conversion. The performance of 3D-ORC is calculated for the recovery of waste heat of internal combustion engines and compared with the simple ORC using pure and zeotropic working fluids. The results show that the performance of 3D-ORC is better than simple ORC under the same conditions.

Regenerative braking technique, which can improve the efficiency of energy conversion and increase the driving range, is one of the key technologies of core competitiveness of electric vehicles (EVs). In this paper, a novel control strategy of regenerative braking is proposed based on a novel definition method of braking intensity, which is applied to all braking condition. Then, according to the slope information, the dynamic distribution algorithm of the front and rear axle is presented. Next, based on logic threshold control algorithm with the input of z and I, the distribution relationship between electric and mechanical braking is determined. Finally, the effectiveness of the proposed control strategy has been validated in MATLAB/Simulink. Simulation results show that the modified control strategy is effective on road conditions with different slope.

The Wells turbine is a self-rectifying axial turbine widely used in wave energy conversion systems based on the Oscillating Water Column (OWC) principle. In these systems, the periodic movement of the water surface inside a chamber open to the sea determines an alternating flow of air inside a duct, where a Wells turbine can be used to convert flow energy into mechanical energy. The architectural simplicity and the reliability of the Wells turbine represent its strengths, while the limited operating range due to the aerodynamic stall of the blades at high flow rates is probably its greatest drawback, as it limits the performance of the entire system. In this paper, a computational investigation on the aerodynamic performance of a variable-pitch Wells turbine is presented. Fluid dynamics simulations were conducted using commercial CFD software and focused on defining machine performance at different flow rates and blade pitch angles. Numerical results obtained have been exploited to define a pitching law, applicable for a period of operation of the OWC system, which allows to adapt the blade’s setting angle to the variable relative flow, thus obtaining an extension of the machine’s operating range, and maximizing energy production.

This paper focuses on the coordinated operation of the electricity, gas and district heating systems in urban areas where multi-energy systems belong to a single entity. The energy conversions among these three systems are scheduled simultaneously so that the demands of the three systems could be met at the least operation cost and maximum social welfare. A nonlinear optimization problem is formulated considering the detailed network constraints in the integrated system. A case study is carried out to show the effectiveness and feasibility of the proposed approach.

Multi-vector energy systems take into account synergies between different energy vectors (cooling/heat/electricity/gas), which will increase the flexibility for equalising the fluctuations from the renewable energy, and thus facilitate the penetration of renewable energy. This paper focuses on developing whole-system analysis and planning methods of energy conversion and storage devices in multi-vector energy systems, to achieve an overall optimum of energy systems. Various energy conversion and storage devices (such as photovoltaic, CHP, gas boilers, battery energy storage systems (BESS), ice storage and so forth) are planned coordinately as an integrated whole. According to the electricity demand during the planning period and the power and energy balance between supply and demand, the size of energy conversion and storage devices are determined to improve the energy efficiency and the energy supply reliability, as well as mitigate carbon emissions.

The efficiency of a wave energy converter (WEC) device for wave energy conversion depends on many factors, among which the incident wave conditions. In this paper, the case of Moroccan Atlantic shoreline wave energy resource will be presented through the exploitation one year of data records in terms of wave height and period variations. It is found that with its 3 000km Atlantic coastline the global potential of offshore wave energy is nearly of 75 000MW which makes the country able to reinforce significantly its renewable energy resources. As a part of this work, the flow behavior inside the chamber of an oscillating water column (OWC) device has been analyzed by means of a numerical flow simulation code. The flow is set to be incompressible, three dimensional (3D), viscous and unsteady. The turbulence has been modeled with the classical (k-e) turbulent model. Computations have been carried out on the geometry of Pico plant built in Azores. Local flow characteristics have been determined in order to obtain an accurate understanding of the flow behavior inside the chamber.

MMC as a new type of voltage source converter is used more and more widely, its essence is a distributed storage system, there are many advantages by using the topological structure of MMC on power quality integrated control system, the power quality control system of voltage sag mitigation is the important use of MMC energy storage system for power quality compensation process. In this paper, based on the analysis of the topology of MMC, firstly analyzes the essence of energy conversion power quality integrated control system of voltage sag compensation, then the energy storage characteristics were calculated and analyzed, the performance index of voltage sag compensation, finally, the simulation method is used to verify the voltage sag compensation characteristics of power quality integrated control system.

There are interactive performances of climatic control within a car cabin in energy consumption, thermal comfort, and air quality. This paper presents sensitivity analysis of those performance indices coupled with mathematical models of air conditions within a car cabin. Through sensitivity analysis, controlled variables are identified for the most influence on energy consumption, thermal comfort, and air quality in effective climatic control. The performance indices are defined from energy consumption of air conditioning unit, predicted mean vote, and concentration of carbon dioxide while mathematical models of air conditions within a car cabin are developed to determine quantitative impact from controlled variables under given operating conditions. Good agreement of simulated results with experimental data is reported for model validation of a sedan car. Some conclusive comments in case studies are recommended from the proposed methodology. In parking, reducing windshield transmissivity by 5% using cover decreases predicted mean vote index by 0.9%. During driving, amount of supply air and temperature can be adjusted to improve thermal comfort whereas energy consumption increases. It is found that decreasing temperature by 5% is superior since corresponding impact on energy consumption is less than increasing amount of supply air by 5% while a predicted mean vote can be decreased by 20.4%. On the other hands, increasing amount of supply air is the most effective way when thermal comfort and air quality are needed to be improved. Increasing amount of supply air by 5% results in changes of the predicted mean vote index and concentration of carbon dioxide by -17.5%, and -0.74%, respectively.

Reciprocating internal combustion engines (ICE) are still the most used in the sector of the on-the-road transportation, both for passengers and freight. CO2 reduction is the actual technological driver, considering the worldwide greenhouse reduction targets committed by most governments. In ICE more than one third of the fuel energy used is rejected to the environment as thermal waste through the exhaust gases. Therefore, a greater fuel economy could be achieved, if this energy was recovered and converted into useful mechanical or electrical power. This recovery appears very interesting, in particular for those engines that run at almost steady working conditions, like marine, agricultural, industrial or long-hauling vehicle applications. In this paper, an ORC-based power unit was tested on a heavy duty diesel engine. Energetic and exergetic analyses have been carried out in order to assess the real performances of the ORC unit and to individuate differences with the theoretical ones. A single stage impulse axial turbine has been tested in this work, complete with an electric variable speed generator and an AC/DC converter. The tests demonstrated that the energy conversion chain is not negligible at all and an overall net efficiency of the power unit was around 2-3 % with respect to a 10% of thermodynamic efficiency.

Integration of renewable energy with energy conversion application for hot water production is a significant technology to be studied for industrial, commercial and residential proposes. It has been further enhanced since the international energy agency (IEA) puts effort to standardize such kind of technology. In this paper, a novel study has been carried out experimentally to control an indirect solar assisted heat pump (IDX-SAHP) system integrated with a latent heat storage (PCM) tank. The PCM heat exchanger tank was designed specially and controlled automatically which allowed storing excess energy during the day and releasing it when needed. In addition, a system control strategy has been purposely designed and implemented in a Building Management System (BMS) to ensure the stable and reliable system operations. The experimental results show that the PCM heat exchanger tank installation has a significant effect on the system operation stability and can improve the COP of the IDX-SAHP system at different weather conditions and a specified hot water load profile.

Piezoelectric floors generate many microwatts up to many watts per step, depending on space pedestrians’ frequency and piezoelectric technology. Although there are a number of earnest researches that have focused on harvesting power from piezoelectric floors tiles, the piezoelectric application is still hindered by many factors, which leads to the deprivation of the advantages of this technology. The research addresses how to get the Maximum benefits from piezoelectric energy harvesting floor in Buildings’ interior spaces, according to the various weight of every usage factors, and through the integration of different kind of piezoelectric technology capabilities. This Paper seeks to spread piezoelectric energy harvesting floor applications, through Facilitate how to conciliate and harmonize between the challenging requirement of usage factors and the application possibilities using a proposed tool. Feasibility study guide supported by various case studies that has been described as a benchmark for the future applications.

One third of the world's end energy consumption is used on heating purposes in the building sector. The larger part of energy used for heating comes from high exergy sources (e.g. coal or gas). Since living spaces are usually heated up to around 20 °C, application of low exergy sources (e.g. solar thermal energy or ground heat sources) is sufficient for low temperature district heating supply. The main target of the work carried out is to demonstrate the advantages of exergy-based assessment for increased efficiency of small scale district heating supply schemes. For this reason different supply scenarios, based on fossil and renewable energy sources, are investigated. The different renewable energy supply units are regarded individually or in two- or three-way combinations. In this study renewable and fossil-based supply are compared on the one hand and on the other hand the benefits of merging several renewable energy suppliers for a small building group with a high energy standard are identified. For evaluation and identification of the best supply solution, the exergetic-based assessment method is applied. Additionally simplified aspects of operational management and estimation of investment costs are used to compare the different supply solutions. The evaluation of the scenarios clearly shows that the combination of innovative supply strategies and exergetic assessment leads to a more “holistic understanding” of the energy conversion chain and offers prospects for optimized low temperature district heating supply. Furthermore economic considerations and an analysis of emissions are to be included in the evaluation. This paper represents modeling, simulation and exergetic analysis of renewable multi-generation units to low temperature district heating supply of a building group and covers a topic from IEA DHC Annex TS1 [1].

With the technology development of energy conversion, multi-energy flow containing electricity, gas and heat is becoming tightly integrated in regional integrated energy systems (RIESs). Interactions and complementarities of various energy systems can bring more environmental and economic benefits but also security problems. This paper studies a decomposed solution of multi-energy flow considering operational constraints, the energy coupling part is analyzed with the concept of energy hub (EH). Multi-energy flow calculation is verified in case study under conditions of different disturbance in EH, showing the necessarily of operational constraint concern. In addition, a multi-energy flow regulation is discussed utilizing gas load-pressure sensitivity analysis.

This paper focuses on a 1 kW-class looped three-stage thermoacoustically-driven cryocooler operating at liquefied natural gas temperature. In this configuration, three identical thermoacoustic engines and one pulse tube cooler are connected by different-diameter resonance tubes. Based on thermoacoustic simulation program, the integral system is designed to achieve high efficiency and large cooling power. Firstly, the optimized dimensions are presented. Acoustic power distribution is then demonstrated to better analysis the energy conversion and transmission process. After that, simulations are performed on the influence of the heating temperature and the mean pressure, which are found to be critical to system performance. The calculated system achieved a cooling capacity of 1170 W and total exergy efficiency of 14.95% at 110 K, showing a good prospect for small-scale NG liquefaction devices.

This paper presents an advanced optimization method for a PV-Wind energy conversion system. This method is based on the use of an advanced control strategies of the DC-DC and AC-DC regulator in PV-Wind standalone system. Within this topology a fuzzy logic control is applied to extract the maximum power point of the photovoltaic generator (PVG) and the wind generator (WG). Consequently an optimal sizing of the system by reducing their total cost is designed.

In the last decade, with increasing global energy demand, pollutant emissions’ level, resulting from the process of energy conversion has been increased significantly. With the intensifying activities of wood exploitation has also increased the wood-waste amount resulted from this process. The situation being given, in the present paper is shown the pollutant emissions impact upon environment, as a result of the conversion process from sawdust briquettes in thermal energy, taking an experimental approach. Meanwhile are presented also the results obtained by analyzing the impact of physical and chemical properties, for the available raw material, upon pollutant emissions quantity generated after combustion process.

In the present paper, the possibility of increasing the thermodynamic efficiency of an electric energy production plant, by using an advanced energy conversion system based on supercritical carbon dioxide (S-CO2) as working fluid, has been analyzed. Since the supercritical carbon dioxide cycles are being considered as a favorable candidate for the next generation of nuclear power plant energy conversion systems, a lead cooled fast reactor has been selected as reference in the present analyses. The main aim of the present study is to compare two different S-CO2 thermal cycles applied on the conversion system of a nuclear power plant. The reference Lead cooled Fast Reactor (LFR) used for the present analyses is the ALFRED reactor, which has a thermal power of 300 MW and it is considered the scaled down prototype of the industrial European Lead Fast Reactor (ELFR). Thermodynamic cycles selected for the present study are a Recompression Cycle and a Brayton Cycle with Regeneration. Each of them has been analyzed under several design conditions regarding the maximum pressure and the regeneration coefficient. Among different design conditions, the solution allowing the maximization of the overall efficiency has been identified. Thermodynamic analyses have been carried out with GateCycle™ v. 6.1.1, which is a General Electric software able to predict design and off-design performance of power plants.

Photovoltaic technology is a consolidated solution for electricity production in residential, commercial and industrial facilities. Despite that, the solar-to-electrical energy conversion is still low and many efforts are still needed in order to increase the panel efficiency. Since the photovoltaic modules performance decreases when the cell temperature increases, solutions have been investigated to cool down the panel with a refrigerated thermal plate installed on the PV rear surface. In standard applications, the photovoltaic thermal panel (PV/T) systems can produce both thermal and electrical energy and they are typically used for domestic hot water (DHW) production. Moreover, hybrid solar panels must be coupled with a heat pump system at the evaporator side, realizing a photovoltaic solar assisted heat pump (PV-SAHP) plant. Generally, a careful design of these integrated systems must involve accurate control strategy to optimize energy savings during operation. In fact, the behavior of the PV/T panels is heavily influenced by the very quick variation of the external conditions during daytime (mainly due to solar irradiation), affecting the working conditions of the other equipment. Therefore, models able to reproduce the dynamic behavior of the PV/T panels represent a flexible tool for developing innovative and user-adapted system control criteria, in a global system optimization perspective. In this context, the aim of the present paper is to describe a simplified numerical model able to reproduce the short time dynamic behavior of the PV/T panel. The model has been validated using experimental data which have been collected during outdoor tests conducted at the University of Genoa using a prototype realized by retrofitting a commercial PV collector. Several simulations have been performed by comparing the PV/T outlet temperature provided by the numerical model against experimental data.

This paper proposed a novel cascade integrated solar combined cycle system, in which concentration solar collector (e.g. parabolic troughs) as direct steam generator and non-concentration collector (e.g. evacuated tubes) are hybrid with combined cycle power plant. Cascaded integration of solar into the combined cycle is achieved in the proposed system. This study analyzes the thermodynamic and economic performance as well as energy conversion characteristics of the proposed hybrid system. The result indicates that the low-cost and high-efficiency solar heat-to-power conversions for this hybrid system are achieved.

Conventional exergy-based analyses reveal options for improving energy conversion systems, but they suffer from some limitations that are addressed by advanced exergy-based analyses. Advanced exergy-based methods are capable of (1) identifying interdependencies among plant components (endogenous/exogenous values), and (2) revealing the potential for improvement (avoidable/unavoidable values). Thus, data obtained from these methods pinpoint strengths and weaknesses of energy conversion systems and are of great importance when complex plants with a large number of interconnected components are considered. This paper presents one of the first applications of an advanced exergoeconomic analysis to a complex power plant. The plant includes a mixed conducting membrane for oxy-fuel combustion and CO2 capture. The results show that for the most influential components of the plant, the largest part of investment cost and of the costs of exergy destruction is unavoidable. Additionally, in most cases the interactions among the components are of lower importance and, for the majority of the components, the endogenous parts of the costs (related to the internal operation of each component) are significantly larger than the corresponding exogenous parts (related to component interactions). Nevertheless, relatively strong interactions have been found among the components that constitute the mixed conducting membrane reactor of the plant.

Concentrated Solar Power plants (CSP) provide several advantages to other energy conversion concepts. However, they are still not competitive in price, compared to conventional power plants. But there is still potential to reduce the cost. The higher heat conductivity of liquid metals leads to very high heat transfer coefficients - ten times higher as with molten salts. This big advantage could increase the efficiency and lower the cost of CSP plants. In order to optimize such a power plant regarding efficiency and cost, detailed information of each component of the system is necessary. This paper shows several system concepts in which liquid metals can be used as heat transfer fluid. In addition, several liquid metal pump types are investigated as well as thermal energy storage concepts. With the assumptions and boundary conditions taken in this model, direct thermal energy storage with liquid metal is prohibitive. But some innovative indirect storage systems with liquid metals show costs in the same range as with a 2-Tank molten salt storage. (C) 2015 The Authors. Published by Elsevier Ltd.

Organic or ‘plastic’ solar cells are attractive for solar photoelectric energy conversion applications where low cost (such as large area), lightweight, and flexible shape are desired. The photoelectric power conversion efficiencies of currently reported organic/polymeric photovoltaic materials are still relatively low (typically less than 10% under AM 1.5 and one Sun intensity), and the three major losses are still severe, i.e., the ‘photon loss’ due to mismatch of materials energy gaps versus the sunlight photon energies, the ‘exciton loss’ and the ‘carrier loss’ due to poor solid state morphologies of existing polymeric donor/acceptor binary systems. Therefore, both molecular frontier orbitals (HOMOs, LUMOs) and phase morphologies need to be engineered to further enhance the efficiency. In this paper, our recent efforts on frontier orbital and energy gap engineering and terminal functionalizations of conjugated polymer blocks, and a donor-bridge-acceptor type block copolymer approach will be reviewed. For instance, a new donor-bridge-acceptor or DBA type conjugated block copolymer system has been successfully synthesized, characterized, and solar cells based on the new materials has been preliminarily tested revealing better performance of the block copolymer system versus the donor/acceptor simple blend system. In addition, dye sensitized polymer and organic/inorganic hybrid nanostructure solar cells were also investigated as dyes absorb more sunlight photon and have more available energy levels and gaps that can better match the solar spectrum than traditional solar cells.

The present paper has the purpose of presenting a recreation and leisure environment designed for activities and expositions related to alternative energy generation concepts, mainly the ones of renewable nature, such as solar energy, contributing to its knowledge spreading. The developed environment is called Renewable Energy and Energy Efficiency Park, and will be built in the city of Tucurui, state of Para, Brazil.The park will be part of a Technology Facility near the Hydroelectric Power Plant of Tucurui, which is owned and operated by ELETROBRAS ELETRONORTE, and will be open to visitors of all ages, mainly to schools. The article describes the projects to be installed in the playground, which are: a small auto-race track for model cars with batteries recharged by photovoltaic solar energy, playground toys designed to produce energy when in use, an artificial lake decorated with toys driven by solar energy. The small speedway is intended for RC car races, with their batteries being charged by photovoltaic modules, through a charge controller and a lead-acid battery bank. The playground toys, such as slide, swing, teeter-totter and carousel are driven while the children enjoy themselves and the energy generated by their movement is displayed in a power indicator. These toys have electromechanical energy conversion systems made of speed multipliers, DC generators and electronic systems for power conditioning, using lead-acid batteries, converters and DC/AC inverters. The produced energy can be used to recharge the electronic portable devices of the visitors (such as cell phones, notebooks, tablets, and so on.) The artificial lake has toys driven by photovoltaic energy, and has also a photovoltaic pumping system, to return the water to an elevated reservoir and allow its recirculation through gravitational means to the small lake. As a result, it is expected that the activities will draw public attention to alternative means of producing energy, mainly using solar photovoltaic, and also to the need of a more rational energy use. It is also expected that the children be encouraged to understand the energy conversion processes, and be aware of the necessity of environment preservation.

We recently demonstrated at imec a relatively simple process sequence for the formation of copper based front contacts consisting of: i) defining the front contact pattern by laser ablation ii) plating of the contacts using Ni/Cu/Ag in a single plating sequence and finally iii) contact sintering. In this paper, we conduct a power loss analysis of the best 20.5% (confirmed by ISE CalLab) PERC solar cell produced on 125 mm magnetically pulled CZ (m-CZ) Si with Ni/Cu/Ag contacts. Based on this power loss analysis, we estimate potential improvements in cell design enabling >21% energy conversion efficiencies.

China's CO2 emission increase has attracted world's attention. This paper analyzed dominant factors that affect changes in China's CO2 emission from 1980 to 2007, which indicates that economic scale and energy saving are two major factors attributable to increase and decrease of CO2 emission, while energy conversion and population scale are less dominant factors. In the future, energy efficiency factor will still take the dominant position while energy conversion will play an increasingly important role, and economic growth rate and industrial structure transformation will become important restrictive factors while population reduction effect size will remain the least changeable factor.

The 73rd Conference of the Italian Thermal Machines Engineering Association (ATI) was held in Pisa (Italy) on September 12-14, 2018. The conference was organized by ATI and the University of Pisa. The main topic of this conference edition was: “Innovation and research for a sustainable energy future” In the last 10 years, the share of renewable sources in the energy mix of several countries has increased at a steady pace. This led to a revolution in the way energy conversion is conceived and distributed in comparison to a fossil based system. Nowadays, thinking about a 100% renewable energy system is no more just a dream. Nevertheless, the transition to this future implies several critical decisions from the technical and economic point of view. The 73rd ATI conference was the opportunity to discuss these topics, present new frontiers of the energy engineering research and promote the cooperation between researchers. The topics of the conference were: Heat Transfer and Fluid Dynamics, Energetics of Buildings, Air Conditioning and Refrigeration, Environmental Aspects of Energy Conversion, Renewable Energy, Advanced Energy Conversion and Storage Systems, Innovative Propulsion Systems and Internal Combustion Engines, Turbomachinery, Combustion and Fuels, Fluid Power. This issue of Energy Procedia includes all the papers presented at the conference, 143 in oral form and 20 in the poster session reserved to PhD students. The conference also included a plenary session and two panel sessions with outstanding keynote speakers from both academy and industry. The Guest Editors of the 73rd Conference of the Italian Thermal Machines Engineering Association

The hybrid power sources, particularly type renewable is one of advanced solutions in the field of energy including wind-photovoltaic type, designed to ensure reliability of system operation or chain energy conversion with better management and control. In this paper, we analyze the modeling and simulation of an energy conversion system based on a double-fed induction machine (DFIM) powered by a hybrid renewable source. The results obtained are very advanced and satisfactory.

This article evaluated the energy effeciency in Hebei Province using some indicators such as comprehensive energy consumption, efficiency of energy transformation. Then it makes a comparative analysis about the HeBei Province's status in the country's energy conservation. The final part of the paper predicts energy consumption indicators in HeBei province from 2009 to 2013.

Standalone solar power system provides simple yet flexible solution to certain applications which demand high mobility. This paper introduces the design of a single solar panel powered induction machine-driven water pump system, which is used in an on-board nanofilteration system. The system configuration is evaluated at the first stage to provide high ratio voltage step-up; and complementary PWM and space vector PWM scheme is chosen for dc-dc stage and dc-ac stage respectively; V/F based control scheme is designed and integrated with maximum power point tracking algorithm for the best use of solar panel. The control system is implemented digitally in a TMS320F2812 DSC. Meaningful mode of operation is tested and satisfactory experimental results are collected.

The pursuit of innovative architectural designs and the development of novel and integrated energy conversion, storage, and distribution technologies presents a challenge for existing building performance simulation (BPS) tools. No single BPS tool offers sufficient capabilities and the flexibility to resolve all the possible design variants of interest. The development of a co-simulation between the ESP-r and TRNSYS simulation tools has been accomplished to address this need by enabling an integrated simulation approach that rigorously treats both building physics and energy systems. The capabilities of this new modelling environment are demonstrated in this paper.