Center for Renewable Energy Sources CRES
Center for Renewable Energy Sources CRES
Karytsas S.,Center for Renewable Energy Sources CRES |
Choropanitis I.,Center for Renewable Energy Sources CRES
Renewable and Sustainable Energy Reviews | Year: 2017
The residential sector is responsible for 20% of the total energy consumption worldwide, with fossil fuels being its main energy source. Ground Source Heat Pump (GSHP) systems are an alternative option for heating, cooling and Domestic Hot Water (DHW) production in the residential sector, offering several advantages compared to conventional systems. Through a survey, this paper examines the views of people involved in the Greek GSHP sector, regarding existing and future adoption level of residential GSHP systems, dissemination barriers and actions that can contribute to their adoption. The conducted Categorical Principal Components Analysis (CatPCA) indicates that diffusion barriers can be classified to market and information barriers, regulatory and financial barriers, installation barriers and siting barriers, with a) lack of public awareness on the GSHP technology and its benefits, b) economic recession, c) lack of adequate subsidies or tax exemptions for the installation and d) installation cost being considered as the most significant ones. In accordance, diffusion actions that can contribute to the penetration of the technology can be categorized to regulatory and technology improvements, financial incentives and awareness activities, with tax reductions suited for GSHPs, public awareness activities on the technology and its benefits and training activities for installers being considered as the most important ones. © 2017 Elsevier Ltd
Parisio A.,KTH Royal Institute of Technology |
Rikos E.,Center for Renewable Energy Sources CRES |
Tzamalis G.,Center for Renewable Energy Sources CRES |
Glielmo L.,University of Sannio
Applied Energy | Year: 2014
In this paper we deal with the problem of efficiently optimizing microgrid operations while satisfying a time-varying request and operation constraints. Microgrids are subsystems of the distribution grid comprising sufficient generating resources to operate in isolation from the main grid, in a deliberate and controlled way. The Model Predictive Control (MPC) approach is applied for achieving economic efficiency in microgrid operation management. The method is thus applied to an experimental microgrid located in Athens, Greece: experimental results show the feasibility and the effectiveness of the proposed approach. © 2013 Elsevier Ltd.
Kotsiris G.,Agricultural University of Athens |
Androutsopoulos A.,Center for Renewable Energy Sources CRES |
Polychroni E.,Center for Renewable Energy Sources CRES |
Nektarios P.A.,Agricultural University of Athens
Energy and Buildings | Year: 2012
Green roofs cooling and thermal insulating features have been demonstrated in many research projects. However, all efforts mostly have assessed green roof thermal properties under steady state conditions or by computational modeling. The present study evaluated green roof thermal performance in terms of the thermal transmittance coefficient, in real scale and under dynamic conditions. For the study's purposes, five semi-intensive green roof systems were constructed on the roof of an outdoor test cell. It was found that the green roof with 8 cm thick rock wool substrate with 2 cm sod on top had a very low U-value. For the same level of substrate moisture content, the other two green roof systems made of 8 cm deep coarse aggregate substrates with 2 cm sod on top provided higher U-values. In contrast, deeper amounts of same substrates (20 cm) reduced the U-value. The relation between the estimated thermal transmittance and the substrate moisture content was investigated and found to be linear. The green roof systems were also simulated for a single-storey residential building in order to quantify their possible energy savings. The results from the simulation showed that shallow substrates conserve building energy mainly during the summer period of the year. Rock wool and deeper substrates showed significant cooling and thermal insulating features. © 2011 Elsevier B.V.
Carvalho A.D.,Polytechnic Institute of Coimbra |
Mendrinos D.,Center for Renewable Energy Sources CRES |
De Almeida A.T.,University of Coimbra
Renewable and Sustainable Energy Reviews | Year: 2015
The main purpose of this study is to assess the impacts in the European Union (EU) of a fuel switching strategy focused on the replacement of Natural Gas (NG) boilers by high efficiency Heat Pumps (HPs) supplied by electricity with a fast decreasing carbon content. Additionally, to illustrate the high performance of heat pumps, the experimental results of an advanced Ground Source Heat Pump (GSHP) system installed in a service building in Portugal are presented. Based on the analysis carried out, it was found that the large scale use of heat pumps for space heating in buildings can contribute to significant primary energy and CO2 emissions savings, when compared to NG boilers. In Europe, in 2050, through the replacement NG space heating in buildings by high efficiency heat pumps, around 60% of the primary energy required and 90% of the associated CO2 emissions can be saved. At global EU level, in 2050 the European NG dependency on external suppliers can be decreased to 50% and an additional contribution of 5.6% for Renewable Energy Sources (RES) share in the total final energy consumption can be achieved. Furthermore, HPs can also play an important role towards exploiting the increasing penetration of renewable electricity generation, effectively contributing to the replacement of fossil fuels and in particular to decrease the growing natural gas dependency of Europe from risky and unstable countries. © 2015 Elsevier Ltd. All rights reserved.
Patlitzianas K.D.,Center for Renewable Energy Sources CRES |
Skylogiannis G.K.,Center for Renewable Energy Sources CRES |
Papastefanakis D.,Center for Renewable Energy Sources CRES
Energy Conversion and Management | Year: 2013
Greece, as a member of the European Union (EU), has undertaken the obligation to meet the expected goals for the penetration of Renewable Energy Sources (RES) in the national energy balance in compliance with "20-20-20" goals (20% of the Gross Energy Consumption and 40% of the Gross Electricity Consumption should be covered by RES). Although the development of RES, and particularly of Photovoltaic (PV), in Greece during the last years has presented a satisfactory growth, the country is still far away from the above goals. The main reason for this delay is that - except the financial crisis - many licenses are inactive and waiting funding in order to be utilized. Additionally, the latest law (L.4152/2013) has forbidden the interconnection of new PV power Plants to the grid until the end of 2013. The above fact determines the significance of the existing PV Licenses in achieving the national goals. The aim of this paper is to present an integrated approach of qualitative judgments for the PV business opportunities through the assessing of the licenses' value in Greece. The approach, which is based on a Multi Criteria Decision Making (MCDM) theory of quantifying multiple qualitative judgments, takes into account the real factors which can affect the expected production and cost of the PV installation and therefore the RoI (Return of Investment). © 2013 Elsevier Ltd. All rights reserved.
Seferis P.,University of Strathclyde |
Strachan P.,University of Strathclyde |
Dimoudi A.,Democritus University of Thrace |
Androutsopoulos A.,Center for Renewable Energy Sources CRES
Energy and Buildings | Year: 2011
The need for environmental friendly and energy efficient building design has stimulated the design of new facade technologies, including various configurations of double skin facades. This paper investigates the thermal performance of a ventilated wall, both for heating and cooling. A thermal analysis was carried out, paying special attention to the characterization of the heat convection resulting from the buoyancy-induced flow in the open air channel which proved to be a critical aspect of the ventilated wall's behaviour. An integrated thermal and air flow model for the entire system was developed. A model of the ventilated wall construction was developed with the ESP-r simulation program and checked against experimental data from a real-scale test cell facility. The thermal benefits of adding a radiant barrier layer were also investigated. The results showed that this layer was beneficial in terms of the energy performance of the construction. Also, the comparison between the experimental and simulation model results showed satisfactory levels of convergence with the exception of the night hours during the summer period. A sensitivity analysis was also undertaken in order to investigate the main factors and the extent of their effect on the temperature variation inside the ventilated facades. © 2011 Elsevier B.V. All rights reserved.
Tzen E.,Center for Renewable Energy Sources CRES |
Papapetroub M.,WIP Renewable Energies
Desalination and Water Treatment | Year: 2012
The balance between water demand and availability has reached a critical level in many areas of Europe, the result of over-abstraction and prolonged periods of low rainfall or drought. Desalination of seawater and brackish water is one of the alternatives for ensuring a reliably supply of drinking water. Renewable energy sources (RES) coupled to desalination offers a promising prospect for covering the fundamental needs of power and water. Various initiatives and projects over the past few years have been covering the field of RE-desalination. The project entitled "Promotion of RES for Water Production through Desalination, ProDes" started on the 1st of October 2008 and it will run for two years. The ProDes project has been carefully designed in order to build on the past and exiting efforts and coordinate its activities with them in order to maximize the expected outcomes. The present paper presents the first results of the project and its general progress. © 2012 Desalination Publications.
Patlitzianas K.D.,Center for Renewable Energy Sources CRES
Renewable Energy | Year: 2011
Until now, there are some specific constraints that hinder development of solar energy in Egypt. However, Egypt has an adequate sunshine, an extended territory free of inhabitants and the "political will" of its government to reach a share of 20% from RES in the national energy balance by 2020. As a result, the business opportunities for solar energy development in Egypt are really significant. The scope of the paper is to provide insight to the possible investment opportunities of solar energy in Egyptian market, based on a current and wide analysis. Indeed, Egypt is an interesting example to show the practical possibilities of the development of Solar Energy in Southern Mediterranean countries. Based on the excellent collaboration between the European Commission and the Egyptian authorities, the current sector is of high interest for developing European entrepreneurship in Egypt. An appropriate approach was developed for the overview as well as analysis of the business opportunities in Egyptian solar energy market, under the umbrella of a Hellenic Aid programme (2009-2010). © 2011 Elsevier Ltd.
Schepers J.G.,Energy Research Center of the Netherlands |
Obdam T.S.,Energy Research Center of the Netherlands |
Prospathopoulos J.,Center for Renewable Energy Sources CRES
Wind Energy | Year: 2012
This paper describes an analysis of wake measurements from the research farm at the ECN Wind Turbine Test Site Wieringermeer. This research farm is owned and operated by the Energy Research Centre of the Netherlands. The farm consists of five research turbines that are oriented in a single line with a mutual distance of 3.8D(iameter). The turbines are variable speed and pitch controlled, and they have a diameter and a hub height of 80 m. The rated power of the turbines is 2.5 MW. Extensive machine measurements (power, loads, yaw angle and pitch angles) are carried out on these turbines. In parallel, meteorological measurements are done on a 108 m mast that is instrumented at three heights (hub height and hub height ± 70% span) with sonic anemometers and cups and wind vanes. This mast is located at a shortest distance of 2.5D from one of the turbines. Data have been collected over a period of almost 5 years, and they are used to study several phenomena mainly related to wake aerodynamics, e.g. power losses in the wake of up to four wind turbines and meteorological wake phenomena at different distances behind the turbines. Copyright © 2011 John Wiley & Sons, Ltd. Copyright © 2011 John Wiley & Sons, Ltd.
Patlitzianas K.D.,Center for Renewable Energy Sources CRES |
Christos K.,National Technical University of Athens
Energy for Sustainable Development | Year: 2012
The current paper deals with two major problems faced by small islands and isolated areas in Greece. The first is power supply and the second is water supply. The scope of the present paper is to investigate the potential of implementing JESSICA (Joint European Support for Sustainable Investment in City Areas) as a complementary financing instrument for provision of Renewable Energy Sources (RES) electricity and water supply on islands with urban and rural areas. The above analysis is presented through a real case on the Greek island Ios. Considering the intense tourism activity during summer, as well as the isolation characteristics of a big number of Mediterranean Islands, the present solution contributes significantly to the improvement of quality of life. In essence the investment contributes significantly to the overall development of the area fulfilling the three aspects of sustainable development (environmental, economic, and social). © 2011 International Energy Initiative.