A review of the day-ahead natural gas consumption in Denmark:starting point towards forecasting accuracy improvement

Natural gas consumption forecasting is crucial for transmission system operators,distribution system operators,traders,and other players in the market.This work...     

Effects of air psychrometrics on the exergetic efficiency of a wind farm at a coastal mountainous site – An experimental study

In this paper, the most important energy and exergy characteristics of wind energy were examined. Atmospheric variables as air temperature, humidity and pressure and their effects on the wind turbine output were investigated toward wind energy exploitation. It was shown that these usually disregarded meteorological parameters while planning new WFs (Wind Farms), in fact, do play an important role in the farm’s overall exergetic efficiency. The wind potential around a coastal mountainous area was studied based on field measurements. Understanding atmospheric parameters variation appears to be of great importance for estimating energy yield in rough terrain and in this paper special focus was given to that.     

Energy and exergy analysis of the Greek hotel sector: An application

Energy consumption in buildings vary significantly, depending on factors as the use of the building, the construction type, maintenance, existing heating, cooling and lighting systems and other types of services. Hotel buildings have high energy consumption rate, as a result of their unique operational characteristics. Energy consumption in hotels is among the highest in the non-residential building sector in absolute values. Available specific information on the energy characteristics, thermal performance, energy losses, electric loads, and comfort conditions play significant role for the sustainable development of hotel's systems. These data can also be used to identify whether there is space for improvement in new or existing hotels by comparing them against predicted or actual building energy performance. The aim of the present paper is to analyze the energy and exergy utilization in four hotels in Rethimno, Crete (Southern Greece) and in Kassandra, Halkidiki (Northern Greece).     

Integration of a light mobility urban scale hydrogen refuelling station for cycling purposes in the transportation market

Road transportation consists of a significant contributor to total greenhouse gas emissions in developed countries. New alternative technologies in transportation such as electric vehicles aim to reduce substantially vehicle emissions, particularly in urban areas. Incentives of using two-wheel electric vehicles such as bicycles in big cities centres are promoted by local governments, and in fact, some countries are already trying to adopt this transition. An interesting case consists of the use of hydrogen fuel cells in such vehicles to increase their driving range under short refuelling times. To this end, this paper investigated the social and financial prospects of hydrogen infrastructure for city-oriented fuel cell electric vehicles such as bicycles. The results of the research indicated that a light mobility urban hydrogen refuelling station able to provide refuelling processes at pressures of 30 bar with a hydrogen fuel cost of 34.7 €/kgH₂ is more favourable compared to larger stations.     

Exergy analysis of the energy use in Greece

In this work, an analysis is being done on the concept of energy and exergy utilization and an application to the residential and industrial sector of Greece. The energy and exergy flows over the period from 1990 to 2004 were taken into consideration. This period was chosen based on the data reliability. The energy and exergy efficiencies are calculated for the residential and industrial sectors and compared to the findings of a previous study concerning the exergy efficiency of the Greek transport sector. The residential energy and exergy efficiencies for the year 2003 were 22.36% and 20.92%, respectively, whereas the industrial energy and exergy efficiencies for the same year were 53.72% and 51.34%, respectively. The analysis of energy and exergy utilization determines the efficiency of the economy as a whole. The results can play an important role in the establishment of efficiency standards of the energy use in various economy sectors. These standards could be utilized by energy policy makers.     

A layer-recursive formula for the medium filter for volumeconductor problems in radially symmetric layered media [bioelectricityapplication]

Simplified algorithms for the computation of the filter coefficients used in solutions of the forward and inverse volume conductor problems in a multilayered cylindrical geometry are derived. The new algorithms are layer-recursive, as opposed to previous algorithms which were specific for the structure studied. The new algorithms not only eliminate the need to derive algebraically cumbersome filter expressions, but also speed up their numerical evaluation.     

The wind chill temperature effect on a large‐scale PV plant—an exergy approach

In this paper, a detailed exergetic analysis based on the variation of meteorological parameters was performed for a solar power generation system. All wind and solar energy and exergy characteristics were examined in order to identify the variables that affect the power output of the photovoltaic (PV) system. Atmospheric variables such as air temperature, humidity and wind speed and their effects, shadow effects, tracking losses, and low radiation losses of the PV power output were investigated aiming at identifying the real and net solar energy output. It was shown that some usually disregarded atmospheric variables in planning new PV plants, in fact, do play a significant role on the plant's overall exergetic efficiency as wind chill temperature. The solar potential around a windy coastal hilly area was studied and presented on the basis of field measurements and simulations. Understanding atmospheric parameters variation appears to be of great importance for estimating correctly and trustworthy the energy yield, and special focus was given to that in this paper. Copyright © 2012 John Wiley & Sons, Ltd.     

A linear programming approach for the optimal planning of a future energy system. Potential contribution of energy recovery from municipal solid wastes

In the present paper the mismatch between the energy supply levels and the end use, in a broader sense, was studied for the Hellenic energy system. The ultimate objective was to optimize the way to meet the country's energy needs in every different administrative and geographical region using renewable energy sources (RES) and at the same time to define the remaining available space for energy recovery units from municipal solid waste (MSW) in each region to participate in the energy system. Based on the results of the different scenarios examined for meeting the electricity needs using linear programming and by using the exergoeconomic analysis the penetration grade was found for the proposed energy recovery units from MSWs in each region.