نشریه انرژی های تجدیدپذیر و نو
سال هشتم شماره 2 (پیاپی 16، پاییز و زمستان 1400)

The cooling energy has covered most portion of building energy consumption in hot and arid climates. Accordingly, suppling of required energy for cooling systems as well as passive solutions to reduce air temperature are so noticeable. As an effective factor, Phase change materials through changing phase save energy and help to improve natural ventilation as well as thermal comfort. These materials have various types base on their chemical structure and melting point. In this way, optimal PCM selection base on their application and melting point is very important; so that, improve natural ventilation and cooling energy in buildings. This study investigates the properties and behavior of phase change materials for their implementation in building passive cooling systems as well as natural ventilation by reviewing and analyzing valid researches and documents in hot and dry climate of Yazd city. Finally, due to PCMs type, their application, and climate condition, optimal PCM has been found; so that, provide thermal comfort, energy consumption reduction, and natural ventilation. As a result, PCM with melting point of 28 ° C can put the environmental temperature in the thermal comfort zone; besides, improve thermal comfort conditions and natural ventilation.

This paper investigates smart home energy management in consideration of tradeoffs between residential privacy and energy costs. A multi-objective approach that minimizes energy costs and maximizes privacy protection is proposed. This approach leads to a multi-objective optimization problem in which the two objectives addressed in separate dimensions. PSO algorithm that employs a stochastic search used for power scheduling of home appliances and uses deterministic battery control developed accordingly. The proposed approach can avoid some drawbacks faced by conventional weighted-sum methods for multi-objective optimization. Simulations reveal that the proposed approach can maintain a reasonable energy cost while robustly preserving user privacy at a sensible level, finally the numerical results shown and analyzed.

The use of renewable energy sources is important today due to the reduction of fossil fuel sources and the increase in environmental pollution. Biodiesel is one of the types of renewable energies. By 2020, 20% of the fuel used is from renewable sources, Biodiesel is one of the most important strategies to complete these choices and achieve the goal. Biodiesel as biofuel can be used in diesel engines in combination with pure diesel and thus improves combustion conditions and reduces emissions. Biodiesel is produced from different biomass in different ways and processes, this depends on the potential of the area in question and the availability of bio-resources. On the other hand, the technology used in biodiesel production is also important. Given the technology and biomaterials used to produce biodiesel, economic cost and production efficiency will be achieved. Therefore, in the face of increasing demand for biodiesel production, it is important to provide a suitable way to commercialize the biodiesel production process. In this regard, different methods of biodiesel production from different sources are investigated in this research, in order to find the appropriate method for achieving a biodiesel production process. Based on the results of this study, biodiesel production depends on the conditions and availability of primary biofuels, but in general biodiesel production from non-food sources with alkali catalysts are of commercial importance in the process of trans-esterification; this method produces high-efficiency biodiesel (about 98%) and is economically superior to other methods.

Ground Source Heat Pump (GSHP) systems are growing technologies that are widely used to collect energy for different uses. This widely usage can be due to their high efficiency, considerable energy storage potential, and low operating cost. In this paper, a ground source heat pump, which its ground heat exchanger is embedded in the building concrete pile, is going to be analyzed. Building piles, also known as energy piles, reduce the cost of drilling boreholes. In this study, Computational Fluid Dynamics (CFD) is used to evaluate and understand how energy piles work and the effects of some parameters such as thermal conductivity coefficient of the pile, pile diameter, pipe diameter and pile loops are investigated by using it. The results show that the increase of each of these parameters results in rising GSHP efficiency. Furthermore, increasing the number of the pile loops can affect the pressure drop and the power needed for fluid flow. The results of this work can be used for designing or optimizing the performance of the GSHP systems with the ground heat exchanger embedded in the building concrete pile.

The birth rate is higher then the death rate, so the population is growing every day. The waste produced is a function of the population and is on the rise. Most of the waste produced is related to the kitchen, which accounts for approximately 20-65% if the waste. In Iran, 70% of municipal waste is organic matter. One of the main reasons for not separating waste is the hack of material value. Wealthy people are willing to pay extra to reduce the number of garbage transfers. Consumption of energy carriers is directly related to wealth. The rich and large families produce more waste then the rest of society. The per capita waste generation in Boukan city is 793 grams. The rate is higher than the national per capita The birth rate is higher then the death rate, so the population is growing every day. The waste produced is a function of the population and is on the rise. Most of the waste produced is related to the kitchen, which accounts for approximately 20-65% if the waste. In Iran, 70% of municipal waste is organic matter. One of the main reasons for not separating waste is the hack of material value. Wealthy people are willing to pay extra to reduce the number of garbage transfers. Consumption of energy carriers is directly related to wealth. The rich and large families produce more waste then the rest of society. The per capita waste generation in Boukan city is 793 grams. The rate is higher than the national per capita The birth rate is higher then the death rate, so the population is growing every day. The waste produced is a function of the population and is on the rise. Most of the waste produced is related to the kitchen, which accounts for approximately 20-65% if the waste. In Iran, 70% of municipal waste is organic matter. One of the main reasons for not separating waste is the hack of material value. Wealthy people are willing to pay extra to reduce the number of garbage transfers. Consumption of energy carriers is directly related to wealth. The rich and large families produce more waste then the rest of society. The per capita waste generation in Boukan city is 793 grams. The rate is higher than the national per capita and should be eliminated by biogas method and become an opportunity. Choosing a place to build a biogas plant is very important because choosing the wrong place will increase the cost of biogas. It will have negative effects in terms of environmental hazards. According to the selected parameters, near Qormish village is the best place to build a power plant. Among the parameters, human factors are the most important parameter. Fruit is the largest waste of the rich.

Tidal energy is one of the different types of energy sources. Unlike many types of renewable energy, tidal currents are a kinetic and potential source of energy arising from the influence of the Earth's gravitational force. Tidal is one of the few predictable energies in the world that has made it attractive to today's world; So that if it is inhibited, tidal energy can be produced at predetermined times. This type of energy is not able to meet all the needs of the world, but it is a starting point for expanding and acquainting the world with clean and accessible energy. In this paper, we first discuss the emergence and history of tidal energy using and then other methods of tidal energy extraction was introduced, especially one of the new and developing methods called Bluetec, and finally the performance of the tidal power plant was investigated.

Today's world is moving towards the use of clean and renewable resources due to the limitation of fossil resources fuels and the environmental problems caused by the consumption of non-renewable fuels. Solar energy is one of these sources that has particular importance due to its proper distribution around the world and its compatibility with the environment. Drying the agricultural products under the sunlight is one of the first uses of this energy. The use of this method leads to the high losses, low efficiency, and poor quality of dried product. To overcome these problems, researchers have designed, built and studied the variety of greenhouse solar dryers. In this study according to different criteria, the introduction and classification of greenhouse dryers have been studied and there is attempt to provide the complete aquantane with this technology for reader. In general, this article is a comprehensive resource for researchers, farmers, and investors that it has been compiled to improve the expansion and industrialization of this science.

Nowadays, with the significant increase in the activities and budgets of governments and companies in research, installation and operation of renewable energy systems, the total cost of production of renewable energies are drastically reduced. Currently, Investing in the biomass-based power plant leads to waste management, the production of electricity as well as generation many employments. Therefore, several policies and incentives have been proposed in different countries. In this article, the various technologies of energy extraction from biomass resources and comparative studies of the worldwide development of biomass-based power plant are conducted. The current state of operation of these power plants, jobs and investments, levelized cost of energy, and the future goals and development policies of this technology in different countries are introduced. The results represents that in Iran, despite the existence of valid upstream regulation, there has been no firm determination to develop these power plants. However, according to the goals of the countries in the region such as Pakistan and Turkey, facilitation laws and financial incentives should be adopted in Iran.

Polycrystalline silicon wafers are produced by carbothermic reduction of silicon oxides in electric arc furnaces. Leader silicon wafer producer companies use emerging production technologies to reduce the production cost of silicon wafers. These efforts lead to reduce the production cost of silicon wafers by 66%. Emerging technologies for production of kerfless silicon wafers with the low thickness are studied in this paper. Using of these technologies in comparison with the conventional production methods lead to reduce the production cost remarkably. These emerging technologies improved the value chain of silicon wafers of solar cell panels. Conventional methods of silicon wafers manufacturing produce high amount of kerf. Wafers produced with these emerging methods have good technical specifications such as thickness, total thickness variation and mechanical properties. These are drivers of the future of this technology.

According to energy economists, increasing efficiency and utilizing renewable energy sources, especially solar energy, is the most effective way to achieve sustainable development goals, provide economic benefits, increase energy security and reduce environmental pollution. In the present study, technical and economic evaluation of the role of investment in the construction of solar power plants (photovoltaics) on sustainable development of Boroujerd city was used using engineering economics method and economic analysis method and RETScreen software. The results show that the assumed photovoltaic power plant has an economic justification with an assumed megawatt period with a return on investment of 4.3 years, an internal rate of return of 28.1%, a net present value of 645.24 billion rials and a profit-to-cost ratio of 9.8. This power plant will produce 2197 MWh of electricity per year (about 0.39% of the total electricity required by the city) and 257 similar power plants are needed to provide the total electricity consumption of Boroujerd city. With the construction of this power plant, the annual emission of greenhouse gases equal to 365.2 barrels of crude oil has not been reduced. Also, this one-megawatt power plant saves 8.5 billion rials per year in fossil fuel, water and greenhouse gas emissions. This amount is equal to 11.7% of the initial construction costs of this power plant, which in addition to selling electricity generated, has positive social effects on society. With the approximate extension of this power plant to a power plant that provides the total consumption of Boroujerd city, 21955.65 billion Rials will be saved in the above cases every year. It is proposed that the government and the Ministry of Energy support the existing solar potentials in the city by providing the necessary funds and facilities for the construction of solar power plants (photovoltaics) with a capacity of one megawatt. Also, by doing this, a lot of savings will be made in the consumption of fossil energy resources, water and greenhouse gas emissions, and the interests of future generations of sustainable energy conservation and development in this city will be realized.

With the growing level of welfare and economic development of societies, sustainable energy supply as a driver of growth has become one of the fundamental human challenges. In recent decades, excessive consumption of fossil fuels has raised concerns about energy security and climate change. Therefore, the use of renewable and sustainable energy sources has become a priority. One of the renewable sources of energy that has high conversion efficiency is hydrogen and fuel cell technology. Electricity generation from other renewable sources such as wind, solar, hydropower, and geothermal has several limitations due to their dependence on environmental and climatic conditions. Among the introduced green options, hydrogen has converted to an option that meets the essentials of sustainable development for energy production and storage because of its abundance and diversity of production sources. Hydrogen is an attractive energy carrier for electricity generation and transportation applications due to its high potential energy efficiency and low emissions. Currently, most of the hydrogen needs (more than 90 percent) are produced from hydrocarbon sources. The global demand for hydrogen is about 70 million tons, of which more than 90 percent is spent on refining fossil fuels and producing chemicals. In this research, the hydrogen production and storage processes have been studied.

The purpose of this research is to design energy storage tanks using phase change material (PCM) in air conditioning system that PCM is part of the heat pump system and is connected directly to the air conditioner. From simulation and modeling methods through coding in software, parametric analysis, as well as introduction and suggestions for use a suitable PCM to store and reduce energy consumption in the building and check the performance of the heat exchanger in the latent heat storage using phase change materials is effective, are discussed. In this paper, first the thermal and refrigeration loads calculated using Carrier software and in the following, the cooling and heating process is simulated. Finally, from the phase change material in different modes used for energy storage in cooling and heating processes and is simulated in EES software. After modeling analysis with a minimum temperature of -5°C and maximum temperature 38°C considered and in different situations, the most suitable option for PCM tank mode in the heating process at the inlet temperature 35°C using 20 pipes in each row and PCM tank mode in the cooling process at the inlet temperature 10°C and selected using 22 tubes in each row.

One of the applications of solar energy is solar absorption cooling system in air conditioning systems. Energy for these systems is supplied using a solar system. In this research, two different problems have been investigated by changing the conditions of an absorption system. So, the pressure in the low pressure region in one of the problems and the pressure in the high pressure region in the other problems is constant. Therefore, the best operating mode can be investigated for the selected system. According to the conditions of this problem, the best operation conditions for this selected solar absorption system were evaporator temperature of 7°C and heat flux of 530W/m2. Finally, some important parameters of the solar collector (glass cover thickness, distance between the absorber pipes, distance between the absorber plate and the glass cover, specific heat capacity of the fluid, heat transfer coefficient of air, heat transfer coefficient of fluid) are optimized to supply the required load of the absorption system. According to the results, the glass cover thickness, the distance between the absorber plate and the glass cover, and the heat transfer coefficient of the fluid are in the optimal conditions. But, the heat absorbed in the collector can be increased by about 10% by changing the distance between the absorber pipes, the specific heat capacity of the fluid, and the heat transfer coefficient of the air. Also, the present results error were about 1% and 1.5% for modeling of the solar collector and the absorption system, respectively.

In recent years, increasing demand for electricity, along with pollution and the depletion of fossil fuels, has encouraged countries around the world to use renewable energy. Small hydropower plants are one of the newest renewable power plants that can be built on small rivers without the need for a dam. In this article, the construction of these power plants, feasibility studies and related economic analyzes, and finally, the work done and their potential capacities, in Iran, will be discussed. The results show that there is a lot of potential for these power plants in many countries of the world, especially developing countries. Easier construction and operation, less environmental problems and the ability to participate in the microgrid are the most important advantages of these power plants. Furthermore, the construction of these power plants in rural areas and away from the network can lead to job creation; Pursue economic benefits and reduce the dependence of these areas on the main power system. Advances in research in recent years have made small hydropower plants a mature and versatile technology that, if technical, social, and environmental barriers are removed, along with appropriate legislation and incentive policies, can play a significant role in meeting the demand for electricity from renewable resources.

One of the concerns in the current world is the depletion of non-renewable energies reserves. In the urban space, the factor affecting such energies are educational buildings with high energy consumption. Green roof system is a suitable solution to improve energy consumption in these buildings. This research aims to optimize energy consumption in educational buildings and with descriptive-analytical research method, has addressed the issue of green roof system with Minimum load on the roof structure and its impact on energy consumption of these buildings. Also, a sample of primary school in Isfahan city with a simple roof was simulated in terms of energy consumption by Design builder software. After that, this primary school was simulated again with all main information about green roof system. Finally, the results show that green roof system with grass vegetation that has shallow depth of root and growing medium, has caused a minimum load on the roof structure and optimized energy consumption of cooling and heating systems of this educational building and reduced the total energy consumption of this building by 4.8% during one year.

Most of the regions with high solar potential for the development of photovoltaic systems are arid and deserted regions such as the Middle East and North Africa. In such regions, dust activities affect the output of photovoltaic panels critically. With the goal to investigate dust activities in Iran and the parameters affecting dust accumulation on the surface of photovoltaic panels, the current article conducted a comprehensive review of the related documents. Studies carried out in this regard, showed that in the recent years, the frequency and severity of dust activities in Iran have been significantly increased. The reasons for such changes and the main origins of dust activities in Iran were described in detailed. Furthermore, the physical and chemical properties of dust particles collected from the surface of panels in different regions were determined. Moreover, by reviewing the literature, the parameters affecting dust accumulation on the photovoltaic panels were categorized and the impact of each of these parameters were described in detail. The results of the current study can serve as a thorough reference for researchers, designers, and engineers in regions struggling with dust events.

The purpose of this study is to identify the possibility, barriers and requirements of utilization renewable energy in the greenhouses of branch flowers) flowers and ornamental plants( of Khuzestan province. Due to high energy consumption and high costs in greenhouse production, this study was conducted to evaluate the possibility, barriers and requirements of using renewable energy. The research method was applied and survey and to do it, a researcher-made questionnaire, the validity and reliability of which was determined, was distributed among 165 greenhouse users of branch flowers in Khuzestan province as a statistical sample. Validity was obtained through the Patel of Experts and reliability was obtained through the Cronbach's alpha coefficient. Based on the research findings, all the requirements for the use of renewable energy were identified. Also, based on the results, 42.1% with a frequency of 59 people expressed the possibility of using renewable energy in greenhouses at a moderate level. Findings showed that there is a significant relationship between educational, technical, economic, social, policy and cultural requirements with the possibility of using renewable energy. The findings also showed that there is a significant relationship between educational, technical, economic, social, policy and cultural requirements with the possibility of using renewable energy. Further factor analysis of barriers to the use of renewable energy showed that educational and managerial poverty, poor support services, incompatibility with greenhouse conditions, lack of financial support, lack of technical facilities and lack of knowledge and awareness are the most important barriers and non-use of these energies.