George Xydis
Technical University of Denmark
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Publication
Featured researches published by George Xydis.
International Journal of Green Energy | 2013
Christopher J. Koroneos; George Xydis; A. Polyzakis
The efficient use of renewable energy sources (RES) is one of the major issues in the modern energy sector. The objective of this work was to examine the potential of wind energy, solar energy (e.g., photovoltaics), and biomass energy sources to meet the current energy use in the island of Lemnos in Greece. An optimization methodology was applied to the energy system of the island, where various RES are abundant and could be exploited to satisfy part of the islands energy needs. An optimization model has been developed having as an objective the satisfaction of Lemnos Island energy needs from RES taking into consideration a multiplicity of criteria such as environmental impacts, energy demand, energy cost, and resources availability. A series of solutions have resulted, based on deterministic model runs, providing decision makers the flexibility to choose the appropriate solution based on the given situation.
Indoor and Built Environment | 2009
George Xydis
In this paper, the availability of different Low Carbon Technologies (LCT) is examined using the method of Exergy Analysis. LCT utilization plays a significant role in the Urban Environment. In many areas, as in construction industry, in fuels and ‘‘conventional’’ energy production, in renewable energy sources (RES), and in transportation there is a focus on technologies that offer the greatest carbon-saving potential. RES offer different LCT as biomass-local electricity and heat generation, geothermal, hydro energy, solar photovoltaic, solar thermal electric (high-temperature generation), solar water-heating collectors, tidal energy, wave energy, and wind power. Continuously increased energy consumption over the last decades in all sectors indicates that a wider LCT utilization is needed. An initial analysis is presented and an availability analysis is been implemented in order to identify whether there is room for more improvement based on the plan for a cost-effective contribution to carbon saving in short and longer term. The ultimate aim of the present study is to analyze the exergy utilization of LCT in order to gain insights of their efficiency
International Journal of Sustainable Development | 2005
Christopher J. Koroneos; George Xydis
An optimisation methodology is applied on the islands of Kephalonia and Ithaca (Prefecture of Kephalonia) in Greece, where various Renewable Energy Sources (RES) can be found and could be exploited to satisfy part of their energy needs. These resources are examined and a case study is performed for Kephalonia that involves an application of specific mathematical tools that will lead to a set of energy solutions. Many scenarios of cases were examined where the requirements of certain end uses were increased and also cases where some of the renewable energy systems were not at the maximum of their potential.
ieee pes international conference and exhibition on innovative smart grid technologies | 2011
G. Romanovsky; George Xydis; Joseph Mutale
While there are presently different options for renewable and distributed generation (RES/DG) to participate in the UK electricity market, none of the market options is specifically tailored for such types of generation and in particular, the smaller (up to 5 MW) RES/DG. This is because the UK has a number of specific historical, technical and economic reasons that significantly influenced the ability of the smaller size RES/DG to participate in the electricity market and in provision of balancing services in accordance with the UK National Grid requirements. This paper discusses some perspectives and approaches aiming to help stand alone small size and clusters of RES and DG units to participate in the UK electricity market drawing on relevant experience from Denmark.
International Journal of Exergy | 2008
A.L. Polyzakis; Christopher J. Koroneos; George Xydis; A. Malkogianni
Economic and environmental considerations dictate the need for improved fuel utilisation in thermal power stations. To meet this goal, a design project was undertaken to assess the suitability for Combined Cycle application of different Gas Turbine (GT) cycles: Simple, Intercooled, Reheated, Intercooled/Reheated, Intercooled/Reheated/Regenerative cycle. Comparative figures for efficiency and performance were obtained. Exergy analysis will lead to an optimum plant. The proposed Combined Cycle plant would produce 300MW of power (200MW GT cycle and 100MW steam cycle). The reheated GT is the most desirable exergetically, mainly due to its high Exhaust Gas Temperature which results in high steam cycle thermal efficiency.
International Journal of Exergy | 2011
George Xydis; Christopher J. Koroneos; Evanthia A. Nanaki
In this work, the potential of the increase in exergy and energy efficiency of the Greek construction and Food, Drink and Tobacco (FDT) industries has been examined using energy and exergy analysis methodology. These two industries play a vital role towards sustainable development of the country. The continuous increase in energy use in these two industries during the years 1971?2000 shows that both remain steadily in an ascendant orbit. The aim was to analyse and compare the energy use and exergy consumption in the Greek construction and FDT industries to gain insights into each sectors efficiency of energy use.
International Journal of Energy Technology and Policy | 2008
George Xydis; Christopher J. Koroneos; A. Moropoulou
In the present paper, the potential of the Greek building sector is examined using the energy and exergy analysis methodology. The building sector can play a crucial role in the efforts towards sustainable development. The building sector plays a significant role in the Greek economy as it engages more than 310,000 employees and 32,500 engineers (2003). The building sector has been one of the most rapidly developing sectors of the Greek economy in the last few years. The construction sector contributes significantly to the gross national product in 2005 (10%), notably higher when compared to 1997 (6.4%). Continuously increased energy consumption in the construction sector over the past 40 years (1961&-2001) shows that this industry remains steadily in the ascendant. The aim of the present study is to analyse the energy and exergy utilisation in the Greek building sector in order to gain awareness of the sectors efficiency.
Archive | 2018
Evanthia A. Nanaki; George Xydis
Abstract Anthropogenic activities resulting to the emissions of greenhouse gases (GHGs) to the atmosphere have increased the challenges faced from climate change. The increased need to mitigate the impacts of climate change has brought focus on the adverse impacts of fossil-fuel-based energy on the environment. Renewable energy sources that include biomass, hydroelectric, wind, solar, and geothermal systems and are carbon neutral, releasing relatively no emissions, are a viable solution. This chapter describes the renewable energy potential of EU-28 countries, current trends, and future prospects of energy systems in 2050. Furthermore, this chapter assesses from a technological and economical point of view a strategy for integrating renewable sources into isolated energy systems—located in Cyclades group of islands. The design of renewable energy systems involves three major technological changes: energy savings on the demand side, efficiency improvements in the energy production, and the replacement of fossil fuels by various sources of renewable energy. Based on the case of Cyclades group of islands, this chapter analyzes the problems and perspectives of converting the present energy system of Greek islands into a 100% renewable energy system.
Science of The Total Environment | 2017
George Xydis; Stelios Liaros; Konstantinos Botsis
The study is a qualitative approach and looks into new ways for the effective energy management of a wind farm (WF) operation in a suburban or near-urban environment in order the generated electricity to be utilised for hydroponic farming purposes as well. Since soilless hydroponic indoor systems gain more and more attention one basic goal, among others, is to take advantage of this not typical electricity demand and by managing it, offering to the grid a less fluctuating electricity generation signal. In this paper, a hybrid business model is presented where the Distributed Energy Resources (DER) producer is participating in the electricity markets under competitive processes (spot market, real-time markets etc.) and at the same time acts as a retailer offering - based on the demand - to the hydroponic units for their mass deployment in an area, putting forward an integrated energy-food nexus approach.
International Journal of Green Energy | 2016
George Xydis
ABSTRACT The wind potential around an intensely mountainous area has been studied and an experimental analysis is presented the output of which could be used in the wind farm planning procedure aiming at maximization of the wind power production output of an area. The wind speed of a chosen site of Central Greece was studied based on field measurements around a large mountainous area of Central Greece. Understanding flow in the foothills and the wider area of the mountains is of great importance for estimating wind resource in rough terrain. In this article, special focus was given to the speed-up effect and forced air flow around mountainous masses.