It is believed that Iran is not only rich in fossil fuels, but also in renewable energies. The potential of renewable energies is estimated at many times that of fossil fuels.An effort has been made in recent decades to introduce renewable energies to Iran's basket of energy. Iran is a leader amongst Persian Gulf countries in diversifying its energy basket by introducing renewable energies. Exploitable capacity of hydropower which was 6043 megawatt in 2005 is planned to reach 34351 megawatt in the future. About 92 windmills with a total capacity of 47580 kilowatt are generating electricity in the four provinces of Khorassan, Gilan, Qazvin and East Azarbayjan, while additional capacity of 41680kilowatt is planned as well. Also, units for generating about 176 kilowatt of solar electricity have been erected in rural areas. About 612250 KWh of electricity has been generated during 1997-2005.Besides, about 3788 solar thermal heaters have been installed in rural areas. A geothermal plant with the capacity of 55 megawatt is under construction in two phases in Meshkinshahr. Despite ongoing efforts to develop renewable energies, the subsidy on fossil energies is the major obstacle for the development of renewable energies in Iran. Technical potential of solar heating is estimated at 91000 terawatt hours. Economic potential of solar heating-assuming an interest rate of 14% and electricity price of 5 US cent per KWh-is estimated at the equivalent of 60 million kilowatt of electricity. The elimination of subsidies on fossil fuel prices will facilitate the development of renewable energies. To develop such energies, in case fossil fuel subsidies are not abolished, requires making available credit to the sector at a preferential interest rate.

The sun is the main source of energy that provides light and heat energy. With the advancements in the power electronic components, grid-tied solar PV Systems are readily available for distributed generation to meet the energy requirements of the customers. The objective of this study and analysis is to predict the potential for solar PV systems and solar thermal energy exploration and the potential for mitigating CO2 emissions and economic benefits. A case study is carried out at Shimoga Milk Union Limited (SHIMUL) Dairy, Machanahalli, Shimoga, Karnataka, India, which handles 75 lakh liters of milk, consumes 2,03,524 units of electricity and 1350 tonnes of steam per month. Analysis has been made on the integration of a 600 kW solar PV system with grid and solar water heaters with the necessary infrastructure for supplying electrical and thermal energy. The study Yields the result that a solar PV System produces 60,000 units per month reduces 29.5% of electrical energy imported from the grid and 50 evacuated tube flat plate collector type solar water heaters of 1000-liter capacity to supply the 50,000 liters of hot water to the boiler at 65˚C reduces input of fuel by 23%, reduces the annual reduction of CO2 emission by 1626 tonnes. Return on Investment for solar PV Systems and solar thermal systems is 4.25 years and 2.7 years, respectively. The analysis extended for each of the various fuels typically used in boilers to produce steam. The procedure developed for estimating the potential for economic and environmental benefits using renewable energy sources for the dairy industry could be extended to any of the industrial sectors that need electrical and thermal energy.

Desalination of the brackish water using a passive solar still with a Phase change materials (PCMs) put under the basin liner of the distillation device is dealt with the help of transient mathematical models. To achieve an optimal system, genetic algorithm is used. In order to estimate the desalinated water in a year, the mass of fresh water in two days of midsummer (7 August) and the midwinter (4 February) was calculated as the typical days in summer and winter. It is assumed that the average amount of water produced in these two days will be repeated for all days at the year. The results showed that mass reduction of saline water is lead to Increase of desalinated water mass. A salt hydrate PCM that its thermal conductivity and density were 0. 69 􀭵 􀯠 . 􀯄 and 1505 􀭏 􀭥 􀯠 􀰯 respectively was selected as the optimal PCM. This type of PCM had a higher thermal conductivity and density than other PCMs. The melting point of this type of PCM is 58° C, which is close to the maximum temperature that saline water reaches in the summer. According to considered limitations for inputs of genetic algorithms, water mass, PCM mass and thickness of the glass, 20 kg, 3. 14 kg and 2. 15 mm were selected respectively. The maximum amount of annual produced freshwater In optimal mode obtained 1632 kg per square meter of desalination.

Solar thermal energy is an abundant and unique source of renewable energy and it will become an attractive and competitive option with the common equipment’s if these systems are incorporated with storage units. Packed bed storage system is one of the techniques to store the solar thermal energy which can be used for greenhouses heating, crop drying and space heating due to its simple mechanism and economic feasibility. In this study parameters affecting on PBSS performance and parameters which used for their performance evaluation has been explained. After that we focused on economic evaluation and some of PBSS applications. Between two types of stationary beds and fluidized beds, although the fluidized beds have higher rate of heat and mass transfer but they have more technical problems in design and construction. Between two types of radial flow and axial flow, the radial flow systems can achieve the same efficiency as axial flow system at higher cost. Among solid materials which can be used in stationary beds, cast iron has the highest level of energy density but gravel has recommended because of less refund return period than cast iron. Some of articles mentioned that sand performance is better than the others. Rectangular geometry for cross section of storage unit provides the lowest cost, but it makes high-pressure drop due to corner effects. In a study which use PBSS for greenhouse planting during the night, they see that if the system works for three months, refund return period will be five years.

This research proposes and evaluates an enhanced open-loop photovoltaic evacuated tube solar thermal collector hybrid energy system based on the developed multi-objective energy management strategy that manages and coordinates the hybrid system with a randomly unreliable grid power source to meet the health center's energy demand using TRNSYS software. A technical assessment of the system shows that the system is capable of meeting system load with a solar fraction of 67% even on days with an overcast sky level of radiation as low as 250 W/m2 and only 37.5% grid power availability. Overall, the system has a solar fraction of 80%. The implication of an 80% solar fraction is the large environmental benefit of reducing emissions and improved system economic viability, indicating that the formulated energy management achieves the goal of promoting renewable energy sources in the hybrid system. An economic analysis of the system revealed that it has a payback period of 6.9 years and Net Present Value of $36,985 at the end of the project's lifetime. This demonstrates that the upgrade of the traditional hybrid PVT with an evacuated tube collector operated based on the developed energy management strategy has met the goal of minimising emissions with significant environmental and economic savings.

In the preset study, the performance of a solar assisted heating, ventilation and air conditioning (HVAC) system in an operating theater building was studied. The yearly performances of the existing HVAC system and the system with the added solar collectors were simulated in terms of energy consumption and provided air conditions using a transient system simulation software (TRNSYS). In the modified system, the solar collectors feed a liquid-to-air heat exchanger, which is defined to be replaced with the main heater of the HVAC system during the day times throughout the year. Three solar integrated HVAC system configurations consisting of three types of standard liquid flat-plate collectors namely, Configuration A: unglazed, Configuration B: glazed painted, and Configuration C: evacuated tube solar collectors were examined to determine the most proper configuration in terms of the energy consumption and provided air conditions. Based on the simulation results, all the configurations examined are capable of providing proper air into the space. However, the energy performance of the configurations indicates that the Configuration A has the priority in terms of energy consumption level and is recommended to be implemented in the existing HVAC system.

Research Problem: The development of modern technologies has become a global common infrastructure and priority due to its environmental, economic and social advantages. Due to the increase in population and expansion of the man-made environment and turning to architecture and interior design, the demand for energy for various purposes is increasing day by day. Therefore, the intelligent use of renewable energy plays an important role in improving the sustainability and energy efficiency in architectural design. Research Question: What effect does the geometry of the window and the use of optical shelves have on the reception and optimal use of natural light? Research Method: The purpose of the present research is the feasibility of using new technologies, including optical racks, in architectural design, emphasizing the approach of increasing the efficiency of renewable energy (sunlight) in Arian Tower, Hamedan.  Research method: Applied research has a quantitative nature and data analysis method is combined, descriptive-analytical and simulation. Collecting information is done by field surveys in the space of Aryan Tower and collecting data with devices such as lux meters. By using Design Builder and Ecotect software, the role of light shelves on providing natural lighting in Arian Tower is investigate The Most Important Results and Conclusion: The investigations carried out on the building unit show that the internal parts of the plan do not receive any natural light and this problem causes the increase in energy consumption. It is because the lamps are turned on to provide lighting. By installing a light ledge, which is one of the methods of using renewable energy, an attempt was made to bring the light to the depth of the plan, and this system performed well in performing its task and received the Green Star certificate. Finally, it was concluded that the use of optical shelf has a significant effect in reducing the cold and heat load and especially increasing the lighting load.

Given the economic and environmental importance ascribed to agriculture, there has been a rising focus on adopting greenhouse technology and renewable energy sources as sustainable and eco-friendly in this sector. Due to this emphasis, the current study utilized mathematical modeling of response surface methodology to analyze and optimization of the photovoltaic-thermal system’s performance of data obtained from a greenhouse. Through the use of Design Expert software and optimal factorial design, optimized treatments were achieved. The studied factors were time (ranging from 10 am to 3 pm), fluid types (pure water, SiO2, Al2O3, SiO2, and Al2O3- SiO2), nanoparticle concentrations (0.1%, 0.3%, and 0.5%) and the photovoltaic-thermal system location (inside and outside the greenhouse). The main objective of the optimization conditions was to maximize the energy parameters. The response optimization design was then examined for power, electrical efficiency, thermal efficiency, and total efficiency. The results demonstrated a strong correlation between the statistical model and the collected data (R2>0.90). Based on the experimental design factors, it was determined that the environmental condition of the system and the type of nanofluid had the most significant impact on the response. After implementing the design, the proposed optimal solution, with a desirability of 99%, involved utilizing a 0.5% concentration of Al2O3- SiO2 nanofluid in the system located outside the greenhouse at 3 pm.

The increasing population and rising demand for water and energy supply, along with the exacerbation of environmental pollution effects on natural and human resources, demonstrate the vital need for a cohesive movement toward the water, energy, and environment Nexus (WEEN). Since the electricity generation industry has a significant share in water and fuel consumption and CO2 emissions in Iran, in this study, the application of a combined renewable system in the Zarand Steam Power Plant was evaluated based on the Nexus approach. Solar system designing and carbon balance evaluation during plant lifetime was conducted via PVSyst software in 2021. Also, an environmental model of ReCipe was applied to evaluate the effect of carbon reduction on the ecosystem. The results have shown that replacement of at least 1% of the nominal capacity of the fossil power plant with renewable sources, will significantly prevent 1249/46 t CO2 emission annually in this power plant which is equivalent to 362/160 m3 fossil resources storage and 373/73 TOE.year-1 energy savings. Also, the results showed that in addition to protecting valuable natural resources, the combined cycle will lead to a significant reduction in water demand equivalent to 3660 m3 having the capacity of supplying underground water resources. Considering the benefits of saving water and energy resources and reducing carbon emissions, from the NEXUS approach, in addition to managing energy supply through replacing resources and using water and heat recovery technologies, applying energy demand management policies based on energy efficiency and its environmental effects is suggested..