[en] Transformers are basically designed to operate under nominal voltage, rated frequency and also, pure sinusoidal load current. In recent decade, change in the type of loads and increasing use of power electronic devices with their nonsinusoidal current waveform has distorted the system voltage waveform as well. The losses of transformers include load and no-load losses. No-load loss continuously led to loss of energy in transformers that are connected to the network in all 24 h. With respect to high significance of energy and undesirable impacts of losses on the aging of transformers, the no-load loss is considered as a critical factor. Nowadays, it is necessary to apply a suitable method for calculation of no-load loss in presence of the voltage harmonics and over-excite conditions, especially for distribution transformers, as a result of harmonic increase in the voltage and current in the network and particular applications. In this paper, Finite Element Method (FEM) has been used to simulate nonsinusoidal voltage effects on no-load loss of transformers. Such simulation enables the software to simulate and analyze different electromagnetic parameters such as flux lines, flux density, losses, and etc under different input sources and with high accuracy. In addition, effect of nonsinusoidal voltages on no-load loss has been investigated by a typical experimental transformer using several practical tests. - Highlights: ► FEM has been employed to loss calculation of distribution transformer under distorted voltages. ► This method gives accurate results in comparison with standard or circuit based methods. ► A new version of 3D FEM has been used, this approach is electromagnetic based. ► In literature, FEM always used for study of transformer load loss and most of them based on magneto-static FEM. ► FEM results are validated by experiment for small test transformer

[en] In this paper we investigate the value of capture-readiness by modeling the cost effectiveness of various alternative technological options and focusing on different clean-coal technology pathways. The modeling framework developed is based on stochastic net present value calculations. It allows for consideration of path-dependent and technology-specific risk combinations inherent in the input and output commodities that are relevant for operating the plant. We find that capture-readiness competes with alternative options of power plant replacements and that capture-readiness is not necessarily preferable from an economic perspective. - Highlights: ► An NPV model with technology- and path-dependent risk-adjusted discount rates is developed. ► The relative value of CCS retrofits compared to new power plants is examined. ► The projects, risk structure is important to consider while discounting cash flows. ► CCS retrofits are found to be less attractive compared to new-build power plants. ► The merit of capture-readiness is questionable due to competing other technologies

[en] Many countries are pursuing greenhouse gas (GHG) mitigation policies resulting in the increase of use of renewable sources in the electricity sector to mitigate CO₂ emissions. Nuclear energy is a non-emitting CO₂ source that could be used as part of that policy. However, its main drawback is the high investment required for its deployment. On the other hand, wind power is the clean source preferred option to mitigate CO₂ emissions. However, due to its intermittence backup power is needed, in most of the cases it must be provided with combined cycle thermal plants using natural gas. This study performs an economical comparison of a hypothetical implementation of a nuclear strategy to meet the same CO₂ emissions reduction goal that has been obtained by the actual Spaniard strategy (2005–2010) based on wind power. The investment required in both strategies is assessed under different investment scenarios and electricity production conditions for nuclear power. Also, the cost of electricity generation is compared for both strategies. - Highlights: ► Wind power electricity cost including its backup in Spain is assessed. ► Nuclear power is proposed as an alternative to produce the same CO₂ reduction. ► Nuclear power requires less installed capacity deployment. ► Investment to produce the same CO₂ reduction is smaller using nuclear power. ► Electricity generating cost is less expensive using the nuclear option

[en] Multiple energy generating cycles such as tri-generation cycles, which produce heat and cold in addition to power through burning of a primary fuel, have increasingly been used in recent decades. On the other hand, advanced exergy analysis of thermodynamic systems by splitting exergy destruction into endogenous and exogenous parts identifies internal irreversibilities of each of the components and the effect of these irreversibilities on the performance of other components. Therefore, main sources of exergy destruction in cycles can be highlighted and useful recommendations in order to improve the performance of thermodynamic cycles can be presented. In the present work, a tri-generation cycle with 100 MW power production, 70 MW heat and 9 MW cooling capacity is considered. For this tri-generation cycle, effects of various thermodynamic parameters on the amount of endogenous and exogenous exergy destructions, exergy loss and the amount of fuel consumption, are investigated. The results indicate that, increasing compressor pressure ratio, pre-heater outlet temperature and excess air leads to better combustion and lower exergy loss and fuel consumption. Increasing the mass flow rate of steam generator, while keeping the cycle outlet temperature constant and considering cooling capacity variable, lead to increase the first- and second-law efficiencies of the cycle. - Highlights: ► Advanced exergy analysis is used to analyze a tri-generation cycle. ► Increasing compressor pressure ratio leads to lower exergy loss and fuel consumption. ► Exergy loss is lowered by increasing pre-heater outlet temperature. ► Increasing the air flow rate of the cycle improves the performance of the cycle

[en] Interest in energy savings in urban lighting is gaining traction and has become a priority for municipal administrations. LED (light-emitting diode) technology appears to be the clear future lighting choice. However, this technology is still rapidly developing and has not been sufficiently tested. As an intermediate step, alternative proposals for energy-saving equipment for traditional discharge lamps are desirable so that the current technologies can coexist with the new LED counterparts for the short and medium term. This article provides a comparative study between two efficiency and energy-saving systems for discharge lamps with metal-halide and ceramic technologies, i.e., a lighting flow dimmer-stabilizer and a double-level electronic ballast. - Highlights: ► It has been demonstrated the possibility of regulating ceramic metal-halide lamps with lighting flow dimmer-stabilizer. ► Electronic ballasts can save approximately double quantity of energy than lighting flow dimmer-stabilizers. ► The use of lighting flow dimmer-stabilizer is more profitable than electronic ballasts due to costs and reliability

[en] Biomass gasification using lattice oxygen (BGLO) of natural hematite coupling with steam was conducted in a fluidized bed reactor. The presence of hematite particles evidently facilitated to biomass gasification. Comparing with biomass steam gasification (BSG), carbon conversion and gas yield increased by 7.47% and 11.02%, respectively, and tar content lowered by 51.53%, in BGLO with an S/B of 0.85 at 800 °C. In this case, 62.30% of the lattice oxygen in the hematite particles was consumed in the biomass gasification. The reaction temperature, steam-to-biomass ratio (S/B) and reaction time on the performance of hematite particles were extensively investigated, in terms of gas distribution, heating value, yield and carbon conversion. With the reaction temperature increasing from 750 to 850 °C, the gas yield increased from1.12 to 1.53Nm³/kg, and carbon conversion increased from 77.21% to 95.49%. An optimal S/B ratio of 0.85 was obtained in order to maximize the carbon conversion and gas yield of BGLO. At this ratio, the gas yield reached 1.41Nm³/kg with carbon conversion of 92.98%. The gas concentration was gradually close to that of BSG at the end stage of BGLO due to the active lattice oxygen was depleted with the proceeding of reactions. - Highlights: • Biomass gasification using lattice oxygen (BGLO) was studied with hematite as oxygen carrier under steam atmosphere. • Lattice oxygen can improve evidently the gas yield and carbon conversion efficiency. • BGLO has major advantages of avoiding pure oxygen consumption and reducing tar. • Optimum operating conditions were 800 °C and steam-to-biomass ratio of 0.85

[en] Urban centers have a huge demand for electricity and the growing problem of the solid waste management generated by their population, a relevant social and administrative problem. The correct disposal of the municipal solid waste (MSW) generated in cities is one of the most complex engineering problems that involves logistics, safety, environmental and energetic aspects for its adequate management. Due to a national policy of solid wastes recently promulgated, Brazilian cities are evaluating the technical and economic feasibility of incinerating the non-recyclable waste. São José dos Campos, a São Paulo State industrialized city, is considering the composting of organic waste for biogas production and mass incineration of non-recyclable waste. This paper presents a waste-to-energy system based on the integration of gas turbines to a MSW incinerator for producing thermal and electric energy as an alternative solution for the solid waste disposal in São José dos Campos, SP. A technical and economic feasibility study for the hybrid combined cycle plant is presented and revealed to be attractive when carbon credit and waste tax are included in the project income. - Highlights: ► We model a hybrid waste-to-energy cogeneration system for the disposal of MSW. ► Reference model for MSW treatment consists of biogas burning and composting. ► Hybrid cogeneration solution is superior to the biogas burning reference model. ► Carbon credit and waste tax increase the attractiveness of the proposed solution

[en] In this paper, a novel approach for exhaust heat recovery was proposed to improve IC (internal combustion) engine fuel efficiency and also to achieve the goal for direct usage of methanol as IC engine fuel. An open organic Rankine cycle system using methanol as working medium is coupled to IC engine exhaust pipe for exhaust heat recovery. In the bottom cycle, the working medium first undergoes dissociation and expansion processes, and is then directed back to IC engine as fuel. As the external bottom cycle and the IC engine main cycle are combined together, this scheme forms a combined thermodynamic cycle. Then, this concept was applied to a turbocharged engine, and the corresponding simulation models were built for both of the external bottom cycle and the IC engine main cycle. On this basis, the energy saving potential of this combined cycle was estimated by parametric analyses. Compared to the methanol vapor engine, IC engine in-cylinder efficiency has an increase of 1.4–2.1 percentage points under full load conditions, while the external bottom cycle can increase the fuel efficiency by 3.9–5.2 percentage points at the working pressure of 30 bar. The maximum improvement to the IC engine global fuel efficiency reaches 6.8 percentage points. - Highlights: • A combined thermodynamic cycle using methanol as working medium for IC engine exhaust heat recovery is proposed. • The external bottom cycle of exhaust heat recovery and IC engine working cycle are combined together. • IC engine fuel efficiency could be improved from both in-cylinder working cycle and external bottom cycle. • The maximum improvement to the IC engine global fuel efficiency reaches 6.8 percentage points at full load

[en] Energy efficiency in buildings is an important objective of energy policy and strategy in Europe. A survey questionnaire was conducted among the 27 European Union Member States. This study aims to provide an overview of the current national regulatory framework focusing on three aspects: 1) integration of energy efficiency and renewable energy requirements, 2) translation of investments in energy saving into economic value, 3) commitment towards “nearly zero-energy” target. The study shows that European countries have adopted different approaches in the design of their national regulatory framework. This heterogeneity consists of four main factors: different authorities involved in energy regulations, traditional building regulations and enforcement models, different contextual characteristics, and maturity of the country in the implementation of energy efficiency measures. These differences are important to take into account country's profile in order to improve the sharing of best-practices and energy efficiency governance among European Union Member States. - Highlights: ► We analyze the legal status for energy efficient buildings in 27 European Countries. ► We examine building markets, renewable technology and “nearly zero-energy” targets. ► European Member States provide a heterogeneous environment to the recast of EPBD. ► National regulatory frameworks have evolved different structures and responsibilities. ► We provide directions in further enforcing energy efficiency in buildings regulation

[en] Utilising energy efficiency to lower energy demand in buildings is a key policy goal of the European Commission. This paper presents the results of bottom-up modelling to elucidate the impact of energy efficiency on the EU building stock up to 2050 under three different scenarios. The modelling is performed for eight individual EU countries and a ninth hypothetical entity that represents the remaining nineteen EU countries. The scenarios highlight the roles of different levels of efficiency improvements in the context of increasing floor area and the demand for energy services. From the results it can be concluded that the EC 2020 goals for primary energy savings can be met by focussing on a combination of minimum efficiency construction standards, improved conversion efficiency standards for final energy to useful energy, and a ≥2% annual improvement in end-use efficiency applied at the useful energy level. A comparison of the results obtained in the present study for Spain with the estimates of savings documented in the Spanish Energy Efficiency Action Plan indicate that the plan could lead to the closing of the energy efficiency gap for buildings in that country by 2020. - Highlights: ► Energy demand modelled in EU buildings of both the residential and service sectors. ► Three scenarios proposed for efficiency improvements up to 2050. ► Show that an annual improvement in efficiency of 2% would reduce energy demand by 50%. ► This efficiency target represents a significant challenge for energy policy makers