Mapping the potential for decentralized energy generation based on renewable energy sources in the Republic of Croatia

There are regions in the Republic of Croatia (underdeveloped, devastated by war, depopulated, as well as islands and mountainous areas) which are still disconnected from the electricity network or where the current network capacity is insufficient. In addition, these regions have good renewable energy potential. Since the decentralized energy generation (DEG) covers a broad range of technologies, including many renewable energy technologies (RET) that provide small-scale power at sites close to the users, this concept could be of interest for these locations. This paper identifies the areas in Croatia where such systems could be applied. Consideration is given to geographical locations as well as possible applications. Wind, hydro, solar photovoltaic, geothermal, and biomass conversion systems were analyzed from a technological and economic point of view. Since the renewable energy sources (RES) data for Croatia are rather scarce, the intention was to give a survey of the present situation and an estimate of future potential for DEG based on RES. The energy potential (given as capacity and energy capability) and production costs were calculated on a regional basis and per type of RET. Finally, the RES cost–supply curves for 2006 and 2010 are given.     

Promoting renewable energy sources for heating and cooling in EU-27 countries

In addition to public policies aimed at improving the energy efficiency of buildings, EU authorities have also promoted the use of Renewable Energy Sources for heating and cooling uses (RES H&C). This paper analyses the main policy measures implemented in EU-27 countries up to 2009: i.e. subsidies, tax incentives, financial support and feed-in tariffs. Twenty-three Member States (MSs) have developed some of these policy measures.     

Mathematical modelling of electricity market with renewable energy sources

The paper addresses the electricity market with conventional energy sources on fossil fuel and non-conventional renewable energy sources (RESs) with stochastic operating conditions.A mathematical model of long-run (accounting for development of generation capacities) equilibrium in the market is constructed. The problem of determining optimal parameters providing the maximum social criterion of efficiency is also formulated.The calculations performed have shown that the adequate choice of price cap, environmental tax, subsidies to RESs and consumption tax make it possible to take into account external effects (environmental damage) and to create incentives for investors to construct conventional and renewable energy sources in an optimal (from the society view point) mix.     

Development of an ambient temperature alkaline electrolyser for dynamic operation with renewable energy sources

A comparison is made between the ambient and conventional temperature alkaline electrolysers in terms of operational system, voltage efficiency and corrosion rates. The capital, operational and maintenance costs are reduced by reducing auxiliary equipment as well as auxiliary utilities in the ambient temperature alkaline electrolyser. Also, since auxiliary electricity consumption is reduced, the alkaline electrolyser is capable for dynamic, continuous and fast-response operation with renewable energy sources. The ambient temperature alkaline electrolyser is capable for wider operational range and faster response time when powered by wind energy sources. Although the voltage efficiency for hydrogen production is increased by about 12% at the conventional operating temperature, corrosion rate of the electrode is increased by a factor of about 6.3. The voltage efficiency for hydrogen production, however, is increased by about 12% by employing electrocatalyst in the ambient temperature alkaline electrolyser, and there is benefit of enhancing lifetime durability of the electrode as well as cell components at relatively lower operating temperature.     

Sustainable application of renewable sources in water pumping systems: Optimized energy system configuration

Eighteen years ago, in Portugal, the expenses in a water supply system associated with energy consumption were quite low. However, with the successive crises of energy fuel and the increase of the energy tariff as well as the water demand, the energy consumption is becoming a larger and a more important part of the total budget of water supply pumping systems. Also, new governmental policies, essentially in developed countries, are trying to implement renewable energies. For these reasons, a case-study in Portugal of a water pumping system was analysed to operate connected to solar and wind energy sources.     

An econometric analysis of residential expenditures on energy conservation and renewable energy sources

Economic theory suggests that residential expenditures on energy conservation and renewable energy sources will be determined by the ability of households to purchase conservation inputs, their incentive to invest in conserving energy, the energy efficiency of existing homes and miscellaneous factors such as climate and age of the home-owner. Empirical analyses of energy-related expenditures reported on individual income tax returns confirm the importance of household income, energy price increases and climate conditions in determining energy conservation investments. Income tax credits are also found to have stimulated residential spending on conservation and renewable energy.     

Energy-based system well-being analysis for small systems with intermittent renewable energy sources

One of the fundamental requirements of a power system, especially in a small isolated power system (SIPS), is secure and reliable energy supply. In this paper, a novel Energy-Based System Well-being Analysis framework (EBSWBA) is presented to assess the reliability of systems containing renewable energy sources (RES), fossil-fueled sources and electricity storage. The framework combines the advantages of the well-known System Well-being Analysis (SWBA) and Expected Energy Not-Served (EENS) approaches, thus overcoming the weaknesses of the SWBA by considering all key factors that influence the system adequacy. Furthermore, two techniques are proposed for calculation of the EBSWBA indices: the Monte-Carlo Simulation (MCS) adopted for the EBSWBA framework, and the Contingency Enumeration for Small Isolated Power Systems (CESIPS) technique, which is derived from the Contingency Enumeration (CE) methodology. These techniques enable formation of probability distributions of the indices. The comparison of the results of classical SWBA and EBSWBA when applied to different SIPS architectures, operating schemes and load profiles demonstrates the superiority of EBSWBA over SWBA in terms of rendered information about the system state as well as in terms of computational efficiency, especially when the CESIPS technique is used for calculation of the EBSWBA indices.     

Exergy analysis of a passive solar still

This paper presents a steady-state and transient theoretical exergy analysis of a solar still, focused on the exergy destruction in the components of the still: collector plate, brine and glass cover. The analytical approach states an energy balance for each component resulting in three coupled equations where three parameters—solar irradiance, ambient temperature and insulation thickness—are studied. The energy balances are solved to find temperatures of each component; these temperatures are used to compute energy and exergy flows. Results in the steady-state regime show that the irreversibilities produced in the collector account for the largest exergy destruction, up to 615 W/m² for a 935 W/m² solar exergy input, whereas irreversibility rates in the brine and in the glass cover can be neglected. For the same exergy input a collector, brine and solar still exergy efficiency of 12.9%, 6% and 5% are obtained, respectively. The most influential parameter is solar irradiance. During the transient regime, irreversibility rates and still temperatures find a maximum 6 h after dawn when solar irradiance has a maximum value. However, maximum exergy brine efficiency, close to 93%, is found once T_col<T_w (dusk) and the heat capacity of the brine plays an important role in the modeling of collector–brine interaction. Nocturnal distillation is characterized by very low irreversibility rates due to reduced temperature difference between collector and an increase in exergy efficiency towards dawn due to ambient temperature decrease.     

Exergy analysis of synthetic natural gas production method from biomass

The paper presents the results of exergy analysis for a biomass-to-synthetic natural gas (SNG) conversion process. The presented study is based on wood gasification, which is analysed for different gasification conditions like temperature and/or pressure. The analysed temperature was varied in the range from 650 to 800 °C and the pressure range was from 1 to 15 bar. The main process units of biomass-to-SNG conversion technology are gasifier, gas cleaning, synthesis gas compression, CH₄ synthesis and final SNG conditioning. The results showed that the largest exergy losses take place in the biomass gasifier, CH₄ synthesis part and CO₂ capture unit. The overall exergetic efficiency of the biomass-to-SNG process was estimated in the range of about 69.5–71.8%.     

Potential of renewable energy systems in China

Along with high-speed economic development and increasing energy consumption, the Chinese Government faces a growing pressure to maintain the balance between energy supply and demand. In 2009, China has become both the largest energy consumer and CO₂ emitting country in the world. In this case, the inappropriate energy consumption structure should be changed. As an alternative, a suitable infrastructure for the implementation of renewable energy may serve as a long-term sustainable solution. The perspective of a 100% renewable energy system has been analyzed and discussed in some countries previously. In this process, assessment of domestic renewable energy sources is the first step. Then appropriate methodologies are needed to perform energy system analyses involving the integration of more sustainable strategies. Denmark may serve as an example of how sustainable strategies can be implemented. The Danish system has demonstrated the possibility of converting into a 100% renewable energy system. This paper discusses the perspective of renewable energy in China firstly, and then analyses whether it is suitable to adopt similar methodologies applied in other countries as China approaches a renewable energy system. The conclusion is that China’s domestic renewable energy sources are abundant and show the possibility to cover future energy demand; the methodologies used to analyse a 100% renewable energy system are applicable in China. Therefore, proposing an analysis of a 100% renewable energy system in China is not unreasonable.     

Application of geographical information systems to rural electrification with renewable energy sources

This paper approaches one of the main problems of rural electrification: the choice of the most appropriate technology for each case. The main objective of this project is to apply Geographical Information Systems (GIS) to divide the research zone into areas in that are more appropriate for either conventional or renewable technologies. The approaches for choosing among the different technologies are usually technical and economic; these may be jointly considered by the leveling electric cost (LEC). Determination of the LEC is a complex task that requires knowledge of the capacity factor. This paper shows the conclusions of the technical and economic parameter analysis involved in the determination of the LEC for each technology. This analysis has allowed us to carry out proposals of improvement in the methodology of the GIS of rural electrification. The resulting GIS has been verified in the municipality of Lorca (Murcia, Spain).     

Renewable energy sources in the Mexican electricity sector

This paper analyzes the role of renewable energy sources (RES) in the Mexican electricity sector in the context of the proposed renewable energy bill currently under consideration in the Mexican Congress. This paper was divided into three parts. The first part presents a chronology of institutional background related to the RES. This is followed by an analysis of the coordination and management system of the Mexican electricity sector, which can facilitate the promotion and integration of the RES without significant structural changes. Finally, the pros and cons of the renewable energy bill are analyzed in order to demonstrate the need for greater coherence between the bill and the coordination system of the sector. It is concluded that when inconsistency is eliminated, RES would strongly be promoted in Mexico.     

Renewable energy sources in the Colombian energy policy, analysis and perspectives

In this work; five basic elements for the formulation of a policy on renewable energy sources for Colombia, are discussed. A balance of the institutions of the energy sector related to the formulation, elaboration and execution of plans, programs and projects on renewable energy sources is carried out. The technology costs that take advantage of such sources are compared and the 967 Law issued in 2001 and its regulatory decree are analyzed. This law promotes the efficient and rational use of energy and also promotes the alternative energies.     

An assessment of exploiting renewable energy sources with concerns of policy and technology

In recent years, the Taiwanese government has vigorously promoted the development of renewable energy to engage the challenges of gradual depletion of fossil fuels and oil, as well as the intensification of the greenhouse effect. Since the Sustainable Energy Policy Principles were announced in 2008, Taiwanese government has declared that the development of renewable energy should take into account goals that pertain to energy, the environment, and the economy (3E goals). This study aims to assess the 3E goals and renewable energy sources regulated by the Renewable Energy Development Bill that passed in 2009. The fuzzy analytic hierarchy process (FAHP) is used to resolve the multi-goal problem for achieving our research purposes. That is, this research attempts to reveal the suitable renewable energy sources for the purposes of meeting the 3E policy goals. The results first show that environmental goal is the most important to the development of various renewable energy technologies in Taiwan, followed by the economic and energy goals. Additionally, hydropower, solar energy, and wind energy would be the renewable energy sources utilized in meeting the 3E policy goals.     

A server database system for remote monitoring and operational evaluation of renewable energy sources plants

The development of a server database system for monitoring and operational evaluation of remote Renewable Energy Sources (RES) plants is presented. Meteorological and operational parameters of multiple RES systems are measured and transmitted in real-time to a database (DB) server. An integrated data management system, comprised of programs running on the DB server, displays the received data on screen, stores them on local disk and inserts them in the DB in real-time. Remote clients access the DB using the TCP/IP protocol in order to create charts, calculate statistical and operational parameters regarding each RES plant and perform DB administration actions. The proposed system can be used for the exploration of the available RES potential during the design of RES systems, the development of statistical models describing the spatial variability of RES resources and the remote monitoring and control of RES plants.     

Exergy analysis of solar energy applications

Solar energy is a clean, abundant and easily available renewable energy. Usage of solar energy in different kinds of systems provides scope for several studies on exergy analysis. In the present work, a comprehensive literature review has been carried out on exergy analysis of various solar energy systems. The systems considered under study are solar photovoltaic, solar heating devices, solar water desalination system, solar air conditioning and refrigerators, solar drying process and solar power generation. The summary of exergy analysis and exergetic efficiencies is presented along with the exergy destruction sources.     

Building design: Realising the benefits of renewable energy technologies

The focus of the world's attention on environmental issues in recent years has stimulated responses in many countries which have led to a closer examination of energy conservation strategies for conventional fossil fuels. Buildings are important consumers of energy and thus important contributors to emissions of greenhouse gases into the global atmosphere. The development and adoption of suitable renewable energy technologies has an important role; a review of options indicates benefits and some problems. There are two key-elements to the fulfilling of renewable energy technology potential within the field of building design; firstly the instilling of appropriate skills and attitudes in building design professionals, and secondly the provision of the opportunity for such people to demonstrate their skills. This second element may only be created when the population at large, and clients commissioning building design in particular, become more aware of what can be achieved and what resources are required.     

PEM electrolysis for production of hydrogen from renewable energy sources

PEM electrolysis is a viable alternative for generation of hydrogen from renewable energy sources. Several possible applications are discussed, including grid independent and grid assisted hydrogen generation, use of an electrolyzer for peak shaving, and integrated systems both grid connected and grid independent where electrolytically generated hydrogen is stored and then via fuel cell converted back to electricity when needed. Specific issues regarding the use of PEM electrolyzer in the renewable energy systems are addressed, such as sizing of electrolyzer, intermittent operation, output pressure, oxygen generation, water consumption and efficiency.     

Algerian renewable energy assessment: The challenge of sustainability

Algeria plays a very important role in world energy markets, both as a significant hydrocarbon producer and as an exporter, as well as a key participant in the renewable energy market. Due to its geographical location, Algeria holds one of the highest solar potentials in the world. This paper presents a review of the present renewable energy situation and assesses present and future potential of renewable energy sources (RESs) in Algeria. This paper also discusses the trends and expectation in solar systems applications and the aspects of future implementation of renewable energies in the Middle East and North Africa (MENA) region status. The problem related to the use of RES and polices to enhance the use of these sources are also analysed in this paper. In addition the available capacity building, the technical know-how for each RES technology and localizing manufacturing of renewable energy equipments are defined. The co-importance of both policy and technology investments for the future Algerian markets of RES and competitiveness of the solar/wind approach is emphasized. Some examples of policy significantly impacting Algerian markets are reviewed, and the intention of the new Algerian RES initiative is discussed.     

The energy situation in OIC countries The possible contribution of renewable energy resources

The paper reviews the socioeconomic situation and energy utilization in Organization of Islamic Conference (OIC) countries which vary considerably. The review indicates that growing energy requirements are associated with economic development and population increase. Renewable energy utilization is indicated as an appropriate alternative for providing a considerable portion of future energy demand in certain energy-consuming sectors. When reviewing the present state of the art of major renewable energy technologies, particular attention is paid to both direct and indirect solar technologies. Possible adaption of renewables into the socioeconomic structures of OIC countries is discussed. The programme of action for renewables in the OIC is stressed, pointing to the priority attached to enhancing the renewable energy contribution.