Search results for "energy [jet]"
showing 10 items of 1760 documents
Assessing the gasification potential of five woodchips species by employing a lab-scale fixed-bed downdraft reactor
2015
Abstract This paper is aimed to assess the performance of air blown fixed-bed downdraft gasification of local lignocellulosic biomasses which in perspective of Southern Norway are both available and sustainable. Long rotation forest crops birch, oak and spruce, coupled with energy crops poplar and willow were used as feedstocks. The gasification conditions undertaken were widely varied in-terms of air (∼3.20–4.20 N m3/h) and fuel flow (∼1.70–2.10 kg/h) so that the corresponding equivalence ratio (ER) differed (0.19–0.80) and ultimately reflected to other operational parameters such as bed temperature (∼550–760 °C maximum), producer gas yield (∼1.50–2.30 N m3/kg, wet base), cold gas efficien…
Stationary battery systems in the main world markets: Part 1: Overview of the state-of-the-art
2017
The role of energy storage systems (ESSs) is becoming more and more important in modern power grids, mainly because of the higher penetration of intermittent renewable energy sources (RESs), such as solar and wind power, spurred by advantageous support policies carried out in several countries. The fluctuation nature of the energy produced by RESs is indeed leading to emerging power quality issues or to renewable curtailments. ESSs can be used to balance generation and demand of electricity over time, allowing a higher penetration of RESs into the power network. The energy storage industry is evolving rapidly, and new electrochemical technologies are entering the market. Besides, most elect…
Techno-economic sizing of off-grid hybrid renewable energy system for rural electrification in Sri Lanka
2015
Abstract Off-grid hybrid renewable-energy-based power systems for rural electrification have become an attractive solution for areas where grid electricity is not feasible. Hybrid energy systems use several energy technologies, and the selection of proper technologies with optimum sizing of the selected components has become very important. The objective of this study has been to investigate the optimum configuration of a hybrid system that can supply electricity to a rural community in Sri Lanka. A rural village in Siyambalanduwa (Sri Lanka) comprising approximately 150 households with a resultant daily electricity demand of 270 kWh and a nighttime peak of 25 kW has been studied. This regi…
Design of a grid connected inverter for sustainable small wind farms
2016
The actual definition of sustainability is nowadays widely accepted. It provides a very general indication on what it is, but it reveals unable to assert how it should be reached. However, if one considers the multiplicity of human activities that have led to talk of real process of human settlement on the environment, it is then understood how it is close to the particular mankind activities. Then the task of providing a guidance on what to do within the sustainability concept is delegated case by case. In this paper, with reference to wind renewable source, The Authors give some indications in the design of a voltage source inverters aimed to optimal use of the wind source. In particular …
Studies Energy Efficiency of the Renewable Sources use Considering Climate in Latvia
2015
AbstractThe paper discusses problems of energy supply of buildings using renewable sources given the local climatic conditions. The meteorological conditions in Latvia and Riga for last year were analyzed. In paper shows examples of energy efficient buildings allowing that to provide comfort temperature and indoor air quality. The structure and composition of local building materials, providing good thermal insulation are described. The heating systems for test buildings using renewable energy sources were investigated. The assessment of the energy efficiency of the “air-air” and “air-water” heat pumps is studied.
Supercharging the Double-Fueled Spark Ignition Engine: Performance and Efficiency
2017
Internal combustion engine development focuses mainly on two aspects: fuel economy improvement and pollutant emissions reduction. As a consequence, light duty spark ignition (SI) engines have become smaller, supercharged, and equipped with direct injection and advanced valve train control systems. The use of alternative fuels, such as natural gas (NG) and liquefied petroleum gas (LPG), thanks to their lower cost and environmental impact, widely spread in the automotive market, above all in bifuel vehicles, whose spark ignited engines may run either with gasoline or with gaseous fuel. The authors in previous works experimentally tested the strong engine efficiency increment and pollutant emi…
A model for reactive power tracing by addition of fictitious nodal injections
2012
Abstract This paper proposes an efficient solution to the problem of reactive power flow tracing in electrical transmission networks. For such systems, the tracing techniques used for active power flows cannot be used straightforwardly, due to reactive power variations induced by the line reactances, these variations often being comparable to the powers delivered to the loads. In other words, as is well known, in transmission systems the reactive flows are strongly influenced by the inductive and capacitive effects of the network, making the tracing of power flow and allocation of losses more critical. In this paper, after discussing some methodological aspects, an approach based on the use…
Effects of double ground faults in Wind Farms collector cables
2015
Medium Voltage collector cables of Wind Farms have metal shields connected to the grounding systems of the towers and of the connection station. Thanks to this bonding, when a ground fault occurs, the fault current splits itself among all the grounding systems of the wind farm, this causing a reduction of the ground potential rise at the fault location. Nevertheless, in presence of double ground faults, very high ground potential rises occur at the two fault locations and safety against electric shock is not always assured. In order to study this issue, the paper presents a model for simulating in a simple way the effects of double ground faults occurring in Medium Voltage collectors of ext…
Transition of a Distribution System towards an Active Network. Part I: Preliminary Design and Scenario Perspectives
2011
In an European perspective, the focus of Smart Grids initiatives (SET Plan - Strategic Energy Technology Plan) is strictly linked with the main commitment to achieve the goals of the Climate and Energy Package 20-20-20, at the light of the three main pillars of the European energy policy: competitiveness, sustainability and security of supply. Smart grid technologies will enable load levelling of the electrical grid, allowing a power company to run cleaner power sources - such as hydroelectric, wind, or solar - while reducing the need to use carbon-emitting gas, coal, or oil plants to meet peak demand. In this framework the proposed paper refers about the technical economical feasibility st…
A comparison of two innovative customer power devices for Smart Micro-Grids
2015
The paper presents a comparison of two prototypes of innovative Customer Power Devices designed for applications in Smart Micro-Grids. The devices are both equipped with Energy Storage Systems, consisting in Lithium batteries and have been assembled, independently, by the DIAEE of the University of Rome 'La Sapienza' and the DEIM of the University of Palermo in collaboration with the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA). In the paper, the characteristics and the operating modes of the devices are examined and some consideration on their application in Low Voltage Smart Micro-Grids are provided. © 2015 IEEE.