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Improvement of thermal performance of a solar air heater can be obtained by enhancing the rate of heat transfer. Thermal efficiency of matrix solar air heater is higher in comparison to conventional type. Number of studies has been reported in the literature on the performance of matrix air heater with different material packing and elaborated various parameters such as design; heat transfer enhancement, flow phenomenon and pressure drop in the duct. Majority of the studies revealed an increase in the thermal efficiency for matrix collector as compared to conventional plane solar air heater. This review paper presents an extensive study of the research carried out on matrix solar air heater. Based on literature review, it is concluded that the solar air heaters performed well when packed with porous medium and this is due to the geometrical parameters of porous material. In addition double pass porous bed solar air heaters performed better than single pass. Various types of matrix materials used in the literature and correlations developed for heat transfer and friction factor by different researchers have been presented. Much attention has been devoted in this paper to portrait the development of various types of solar air heaters over the years. The merits and demerits of different models evolved by many researchers have been critically analyzed. Finding in a nut shell is that the drawbacks associated with conventional nonporous solar air heaters such as high heat loss to the ambient, decreased convective heat flow from plate to air, etc. can be overcome by the use of an effective design of porous bed solar air heater. [ABSTRACT FROM AUTHOR]

Given that the first industrial revolution was based on Steam Engine (coal as energy source), and the second on oil and electricity, where both these revolutions are actually "high carbon" revolutions, it is logical to expect that the third industrial revolution should be based on systems of renewable energy sources (RES), in order to minimize the problems arising from climate changes and to achieve sustainable development. However, the usage of the RES technologies and daily/weekly storage of energy and their connection to smart grids is not enough for the expected third industrial revolution. The start of this revolution would require technologies that have a great potential for further development and ability to supply, at any time, the necessary energy and power to a settlement/city, as well as drinking water, meeting the peak load requirements, continuously throughout the year, and independently of external sources of energy and drinking water. This would be provided from intermittent RES energy (solar, wind, etc.) and sea or other unclean source of water as natural resources. In that context, this paper presents a radically new technological solution: Key Engine which uses only natural resources: the sun, sea and gravity, in order to continuously and simultaneously supply a consumer with energy, power and drinking water. This solution has all the essential features required to start a third industrial revolution. The basic unit of Key Engine consists of the solar thermal (ST) generator with parabolic trough collectors through which sea water flows directly, absorbing thermal energy of solar radiation. After the separation of steam from seawater, the steam drives turbines and generators and produces electricity that is delivered to Pump Storage Hydroelectric (PSH) facility with seawater, which balances the daily and seasonal surpluses and shortages of energy, thus ensuring a continuous supply of electric power and energy to a consumer. At the same time, the water that comes out of the turbine, passes through the water treatment unit and is stored in drinking water reservoir, enabling continuous supply of the same consumer with drinking water. The paper presents theoretical aspects of Key Engine, model for optimal sizing and practical formulas for the calculation of characteristic values of the system, which could be the basis for further scientific research, development and innovative solutions that would help engineers in practice for numerous and diverse applications of Key Engine. In order to verify the derived mathematical relationships and models for optimizing the Key Engine in real conditions, the case study of the island of Vis in the Adriatic Sea, Croatia, has been considered, along with total annual irradiance of 1575 kW h/m 2 a, total annual electric energy consumption of 20 GW h and drinking water consumption of 453,382 m 3 . The obtained results: power of ST generator of 52 MW, working volume of the upper reservoir of 7 hm 3 , total annual electric energy production of 62 GW h/a, and drinking water production of 480,754 m 3 /a, clearly show that the new technology can fully meet the needs of the considered consumer for energy and drinking water. As the basic idea of Key Engine relies on the use of natural resources, i.e. RES energy and sea, the paper presents only the starting solution, whereby, apart from the sun, RES can be wind, or other renewable sources, that can perform separation of vapor from seawater and thus produce drinking water, as well as energy simultanously. Also, energy storage may not be performed solely by the PSH technology, but also by any other technology that can provide seasonal balancing of energy. All this suggests that the Key Engine can be understood as an open-source for RES technology development and thus bring changes in all three aspects of sustainable development: economy, society and environment. [ABSTRACT FROM AUTHOR]

Introduction of renewable energy sources (RES) in insular areas is growing on different islands of various regions in the world and the large-scale deployment of renewables in island power systems is appealing to local attention of grid operators as a method to decrease fossil fuel consumption. Planning a grid based on renewable power plants (RPP) presents serious challenges to the normal operation of a power system, precisely on voltage and frequency stability. Despite of its inherent problems, there is a consensus that in near future the RES could supply most of local needs without depending exclusively on fossil fuels. In previous grid code compliance, wind turbines did not required services to support grid operation. Thus, in order to shift to large-scale integration of renewables, the insular grid code ought to incorporate a new set of requirements with the intention of regulating the inclusion of these services. Hence, this paper discusses grid code requirements for large-scale integration of renewables in an island context, as a new contribution to earlier studies. The current trends on grid code formulation, towards an improved integration of distributed renewable resources in island power systems, are addressed. The paper also discusses advanced grid code requirement concepts such as virtual wind inertia and synthetic inertia for improving regulation capability of wind farms and the application of energy storage systems (EES) for enhancing renewable generation integration. Finally, a comparative analysis of insular grid code compliance to these requirements is presented in the European context. [ABSTRACT FROM AUTHOR]

Development of alternative energy sources has become a necessity as fossil energy resources are declining. At the same time, energy demand is rapidly increasing, putting the world on the verge of a global energy crisis. Moreover, the extensive use of conventional energy sources is polluting the environment and causing global warming. On the other hand, wind and other renewable energy sources are viable and clean alternatives to fossil fuels. Low operating cost and extensive availability make wind one of the most advantageous and effective renewable energy sources. This paper provides an exposure to the necessity for deployment of renewable energy sources and the worldwide installed capacity of wind power as well as a review of various wind technologies in conjunction with their applications and devices of operation. Furthermore, this paper discusses the cost of electric generation in wind power plants as well as the economic and environmental policies that advocate the installation of wind energy systems. [ABSTRACT FROM AUTHOR]

Renewable energy hybrid power systems have been proven through their ability to address the limitations of single renewable energy system in terms of power efficiency, stability, and reliability while operating at minimum cost. In this regards many research and practical experiences have been done. The present paper reviews the different hybrid PV–Wind renewable energy hybrid systems used for electrical power generations. Different criteria of sizing the different system components of hybrid renewable energy power plant at the most preferable logistical environmental and economical considerations have been discussed. Also, the paper discussed some of the optimization approaches which are used to compare the energy production cost and performance of different hybrid system configurations using simulation techniques. Based on the fact that, potential of the wind and solar energy is not equal in Oman, this paper will discuss the optimum sizing process of two proposed hybrid PV–Wind plants in Oman. [ABSTRACT FROM AUTHOR]

The main goal of this paper is to argue for the necessity and significance of studying the distributional employment impacts of renewable and new energy development (RNE). Based on the comprehensive review of the methodology and conclusions of existing literatures, this paper builds up an extended input–output model to study RNE’s distributional employment impacts on gender and personnel structure. The case study of China׳s power sector in this paper affirmed earlier doubts that RNE development will indeed aggravate the gender inequality problem and add to the level of mismatch between the structure of labor demand and supply, causing structural unemployment problems. The quantitative analysis in this paper outlined here implies that from 2011 to 2020 the development of RNE will bring about 7 million employment gains, but only 81.8% of which can be realized due to the mismatch problem. The study of China may alert other countries to be less-optimistic about RNE’s employment impacts and reaffirm the need to carry out the distributional employment impacts analysis. This paper concludes with policy suggestions such as providing suitable training and equal promotion opportunities for women, offering courses and vocational trainings to RNE-related majors, in order to reduce the structural unemployment problem and further speed up the development of RNE. [ABSTRACT FROM AUTHOR]

Abstract: Prince Edward Island (PEI) is the smallest province in Canada measuring about 5700 km2 in area with a population of around 130,000 people. Small family farm operation is part of the Island's way of life. However, the dairy industry in North America is undergoing significant structural change. Statistics show a significant decline in the small dairy farms industry, while the number of large operations has been increasing. Advantages for large operations include purchasing energy in large quantities with better price margins and the inherent economy of scale created by such breaks. One strategy for small-scale farms to become competitive is to reduce their energy-related operational costs and greenhouse gas emissions. This can be achieved through taking energy efficiency steps, reducing overall energy consumption and generating energy through renewable energy resources and technologies. This paper uses a case study of a small dairy farm in Oyster Bed Bridge, PEI to gain insight into the direct use of energy within small dairy farms. An energy audit methodology is used to determine the energy intensity of the farm as well as energy efficiency opportunities. The paper also assesses the feasibility of meeting part of the energy demand of the farm with renewable energy generation. Energy efficiency recommendations for the case study farm include lighting retrofitting and regular maintenance of refrigeration condenser units. Renewable energy generation findings include the potential use of an anaerobic digester or a 25 kW wind turbine to generate the majority of the operation's energy. [Copyright &y& Elsevier]

Abstract: The global demand for energy is currently growing beyond the limits of installable generation capacity. To meet future energy demands efficiently, energy security and reliability must be improved and alternative energy sources must be investigated aggressively. An effective energy solution should be able to address long-term issues by utilizing alternative and renewable energy sources. Of the many available renewable sources of energy, solar energy is clearly a promising option as it is extensively available. Solar power, especially as it reaches more competitive levels with other energy sources in terms of cost, may serve to sustain the lives of millions of underprivileged people in developing countries. Furthermore, solar energy devices can benefit the environment and economy of developing countries. This paper illustrates the need for the utilization of alternative energy sources, evaluates the global scenario of installed generation systems, reviews technologies underlying various solar powered devices, and discusses several applications and challenges in this area. In addition, this paper addresses the costs of deployment, maintenance, and operation, as well as economic policies that promote installation of solar energy systems. [Copyright &y& Elsevier]

Abstract The Association of South East Asian Nations (ASEAN) is a diverse region characterized by rapid economic growth, demographic change and urbanization. The dominance of energy supply from non-renewable resources in the region means that the increasing energy demand has implications for energy security, as well as adverse local and global environmental effects. Climatic conditions in the region are favorable for renewable energy (RE) resources, especially but not only wind and solar technologies. ASEAN countries differ strongly in terms of their national policy frameworks and progress in renewable energy development; the overall target of 23% renewables by 2025 is very ambitious under current policy frameworks. This paper identifies a gap between these national policies and local governance, especially in urban areas, which requires attention to ensure future target fulfilment. By employing a new combined correlation and decomposition approach at country and city levels, we investigate the determinants of RE expansion and explore the trend drivers in ASEAN countries from 1995 to 2013. An Impact Matrix is developed to position and interpret the relative push (e.g. policy) and pull (e.g. market) impacts on RE development, and to derive policy recommendations for countries and sectors. The results highlight that urban areas should be the focus of RE policy and governance in addition to rural areas. The tremendous impact of economic growth creates a great impetus for renewable energy development, but urbanization is the second pull for renewable energy extensions. Since the two effects are located in the first quadrant of the Impact Matrix, if strategists affect these factors, they will create the most powerful incentive for renewable energy growth. This confirms that if the strategic aim is to promote renewable energy market development, through policy and governance measures, the focus should be on urban areas, non-electricity sectors and the demand side. [ABSTRACT FROM AUTHOR]

The goal of this paper is to analyze recent developments in the renewable energy sector in the Western Balkans – Albania, Bosnia and Herzegovina, Croatia, Kosovo, Macedonia, Montenegro, Serbia, and Slovenia. In order to achieve this goal, existing knowledge gaps regarding the use of renewable energy as a share of the region׳s final energy consumption had to be filled in. This was done by creating a reliable model for the calculation of these shares for the years 2010 and 2011. The results were then put together with the official data for the years 2009, 2012, and 2013, and a linear trend forecast was included based on the combined data. In this way it was possible to make an estimation of the time frame in which the countries with positive linear trend results would reach their renewable energy use targets. The results of the analysis show inconsistent development of renewable energy sources for countries outside of the EU. Combined with political challenges, such as the natural gas crisis of 2009, this creates increased volatility in the proportion of renewable energy in final energy consumption. Additionally, regulatory and market issues ranging from a lack of appropriate legislation and complicated administrative procedures, to poor coordination between various institutions act as barriers to increased investment in renewable energy. [ABSTRACT FROM AUTHOR]

Inter-area low frequency electromagnetic oscillation (LFEO) in inter-connected power systems is one of the major barriers to improve the dynamic performance of power systems, since they could either limit the amount of power transfer on the tie-lines or endanger the dynamic stability of the power systems. With the high penetration of wind and photovoltaic (PV) power plants in power systems, LFEO is becoming a problem worth more attention in renewable energy age and must be better solved in order to accept more wind and PV power in power systems. Wide-area damping control (WADC) has gained popularity in suppression of inter-area LFEO recently. Many control strategies have been developed on WADC design. This paper aims to provide a general review on practical issues, typical WADC off-line and adaptive design methods and engineering cases regarding WADC implementations. These practical issues include design flow, mode analysis, choice of actuator and feedback signal, system identification and the effect of time delay. In terms of designing WADC controllers, both offline and adaptive methods have been reviewed and compared. Finally, WADC engineering cases all around the world are summarized. [ABSTRACT FROM AUTHOR]

Iran is rich in energy resources and oil has dominated the politico-socio-economic life of this country, but nevertheless Iran has no documented policy and vision for its massive resources. This poses a major challenge to policy makers and the society. It is necessary to have a clear picture of Iran׳s energy status in recent years showing the flow of energy supply, demand, consumption, import and export to know how the energy situation in Iran is and identify its weaknesses and strengths. This paper is the first step in that direction and presents an overview of Iran energy situation and the potential and current state of renewable energy application. The status of energy in Iran is compared to world’s energy status via five key factors, and finally this comparison shows hints for designing roadmap of energy for Iran to attain sustainable and secure energy in long term. The novel contribution of this work is the STEEP analysis of Iran energy situation for designing the long-term supporting mechanisms for sustainable and secure energy for Iran based on Social (S), Technological (T), Economical (E), Environmental (E) and Political (P) criteria. [ABSTRACT FROM AUTHOR]

Renewable energy is one of the most popular topics in utilization of the electric energy resources. There are various types of alternative energy, which can be used as electrical energy. However, the suitableness of the green energy in a certain country is depending on some criteria such as geographical location, the availability of energy and so on. In order to establish the renewable energy, a well-planned strategy and management must be acquired. The main objective of this paper is to analyse the causal relation of some important criteria of project planning and development of a wind energy project in Malaysia. By using a system dynamic approach, it is found that government policies, investment of renewable energy, energy demand, geographical location and fund management are the most important criteria that need to be considered among others. The diagram of causal relationship with reinforcing and balancing loop shows that the application of renewable energy in Malaysia is promising. In addition, the information of the criteria relationship is further investigated by using the stock flow diagram. From the diagram, the factors that affect project's expenditure could be analysed. This is very important to a developing country where more budgets can be allocated for other facilities, cultures, infrastructure, science, and technology development. By utilise the renewable energy in Malaysia, the carbon dioxide emission can be reduced and contribution to a sustainable and long term alternative energy resources country. [ABSTRACT FROM AUTHOR]

The paper provides a comprehensive analysis of the projects aiming the use of renewable energy sources (RES) in Romania, taking into account both the convertible energy potential of this country, as well as the requirements for meeting European Union sustainable energy development targets by 2020. We analyze the current state of renewable energy production facilities in Romania, in correlation with the data collected from 89 energy projects financed through the Operational Sectoral Program Increase of Economic Competitiveness since 2007 until 2013, more than a half of them aiming the development of new RES energy facilities. We also analyze the data quantifying the efficiency of specific investments in renewable energy, in comparison with EU average statistical data and provide some concluding remarks about the difficulties faced by investors during project implementation, given the particularities of the country related with this field. [ABSTRACT FROM AUTHOR]

Abstract: Since the beginning of the last century, energy affairs have always been taken into global consideration due to their effects on economies, policies, security and the environment. Fossil fuels have been the first recourse for global energy supply needs (80% of total energy consumption); nonetheless, owing to the production of greenhouse gases, they are gradually being replaced with renewable energy resources. In addition, renewable energy resources are perpetual, unlike fossil fuels, which may be exhausted in less than one century. From 2005 to 2010 (coinciding with Iran's fourth development program), renewable energy resources enjoyed a double-digit global growth rate as a result of environmentally friendly perception and a reduction in equipment price. Some policies and strategies were globally adopted to support renewable energy resources (Feed-In-Tariff, subsidies, etc.). Iran began utilizing renewable resources from the early 1990s and set targets and policies for renewable energy resource utilization in the fourth development program. However, Iran's trend has not aligned with global trends, and it appears that its enormous fossil fuel reserves overshadow the growth of renewable energy resources in the country. In this paper, the status, achievements and policies of Iran during the fourth development program will be discussed and compared with global trends. [Copyright &y& Elsevier]

Abstract: Korea relies on imported fossil fuels to meet its energy consumption demands. As such, there is a need to investigate alternative energy resources such as renewable energy. In this paper, assessments of the potential of various ocean renewable energy resources in the sea around Korea; potential sources of energy including wave energy, tidal energy, tidal current energy and ocean thermal energy. Tidal energy and tidal current energy are likely to play an important role in meeting the future energy needs of Korea, whereas the potentials of wave energy and ocean thermal energy for the same are relatively low. The level of technical development and the renewable energy market in Korea is currently in an early stage. The government will have to be more aggressive in the promotion of renewable energy to achieve sustainable development in Korea. [Copyright &y& Elsevier]

Abstract: This paper presents the opening talk that briefly surveys the present (May 2011) situation in sustainable energy development. Recent estimates and forecasts of the oil, gas, coal resources and their reserve/production ratio, nuclear and renewable energy potential, and energy uses are surveyed. A brief discussion of the status, sustainability (economic, environmental and social impact), and prospects of fossil, nuclear and renewable energy use, and of power generation is presented. Comments about energy use in general, with more detailed focus on recently emerging game-changing developments of postponement of “peak oil”, nuclear power future following the disaster in Japan, and effects of the recent global economy downturn of global sustainability, are brought up. Ways to resolve the problem of the availability, cost, and sustainability of energy resources alongside the rapidly rising demand are discussed. The author’s view of the promising energy R&D areas, their potential, foreseen improvements and their time scale, and last year’s trends in U.S. government energy funding are presented. [Copyright &y& Elsevier]

The article reports on issues concerning the increasing dependence on nuclear energy for producing electric power and as a potential energy source. Though nuclear energy is considered as a potential energy source to replace the dependence on imported oil, however widespread safety deficiencies in nuclear installations raises the possibility for eventual phase-out of nuclear power. The article report on nuclear power's limited overall potential as it cannot practically displace all the oil used for generating purposes like transportation sectors and others.

Scenarios for the future of renewable energy through 2050 are reviewed to explore how much renewable energy is considered possible or desirable and to inform policymaking. Existing policy targets for 2010 and 2020 are also reviewed for comparison. Common indicators are shares of primary energy, electricity, heat, and transport fuels from renewables. Global, Europe-wide, and country-specific scenarios show 10% to 50% shares of primary energy from renewables by 2050. By 2020, many targets and scenarios show 20% to 35% share of electricity from renewables, increasing to the range 50% to 80% by 2050 under the highest scenarios. Carbon-constrained scenarios for stabilization of emissions or atmospheric concentration depict trade-offs between renewables, nuclear power, and carbon capture and storage (CCS) from coal, most with high energy efficiency. Scenario outcomes differ depending on degree of future policy action, fuel prices, carbon prices, technology cost reductions, and aggregate energy demand, with resource constraints mainly for biomass and biofuels. [ABSTRACT FROM AUTHOR]