• Energy Research
• 7. Clean energy close
• 12. Responsible consumption close
• IR close
• Renewable Energy close

Abstract In the present study, enhancing the heat transfer is experimentally investigated by the electro-hydrodynamics (EHD) through a single-pass air-cooled PV/T (Photovoltaic/Thermal System). The corona wind increases the heat transfer coefficient by producing a secondary flow and vortex, and consequently, increases the PV/T system efficiency. The effects of the corona wind are studied by changing the voltage values and the flow rates in the air channel. The results show that the corona wind is effective on enhancing the system performance; so that the heat transfer coefficient increases by 65% in natural flow regime by applying 11 kV voltage in the pilot setup. Totally, the thermal efficiency of the PV/T system increases up to 28.9%. Also, the effects of corona wind are studied by changing the amount of the applied high voltages and flow rates.

Abstract The aim of the present study is to provide an Atlas of IRAN Offshore Renewable Energy Resources (hereafter called ‘the Atlas’) to map out wave and tidal resources at a national scale, extending over the area of the Persian Gulf and Sea of Oman. Such an Atlas can provide necessary tools to identify the areas with greatest resource potential and within reach of present technology development. To estimate available tidal energy resources at the site, a two-dimensional tidally driven hydrodynamic numerical model of Persian Gulf was developed using the hydrodynamic model in the MIKE 21 Flow Model (MIKE 21HD), with validation using tidal elevation measurements and tidal stream diamonds from Admiralty charts. The results of the model were used to produce a time series of the tidal stream velocity over the simulation period. Moreover, to assess the potential of the wave energy in this site, a model was developed based on six-hourly data from a third generation ocean wave model (ISWM-Iranian Sea Wave Model) covering the period 1992–2003. To ensure the information provided to the Atlas is managed and maintained most effectively, all the derived marine resource parameters have been captured in a structured database, within a Geographical Information System (GIS), so enabling effective data management, presentation and interrogation.

Feed in tariff (FiT) is one of the most efficient ways that many governments throughout the world use to stimulate investment in renewable energies (REs) technology. For governments, financial management of the policy is very challenging as that it needs a considerable amount of budget to support RE producers during the long remuneration period. In this paper, we illuminate that the early growth of REs capacity could be a temporary boost and the system elements would backlash the policy if financial circumstances are not handled well. To show this, we chose Iran as the case, which is in the infancy period of FiT implementation. Iran started the implementation of FiT policy in 2015 aiming to achieve 5 GW of renewable capacity until 2021. Analyses show that the probable financial crisis will not only lead to inefficient REs development after the target time (2021), but may also cause the existing plants to fail. Social tolerance for paying REs tax and potential investors trust emanated from budget related mechanisms are taken into consideration in the system dynamics model developed in this research to reflect those financial effects, which have rarely been considered in the previous researches. To prevent the financial crisis of the FiT funding and to maintain the stable growth in long term, three policy scenarios are analyzed: continuation of the current program with higher FiT rates, adjusting the FiT rates based on the budget status, and adjusting the tax on electricity consumption for the development of REs based on the budget status. The results demonstrate that adjusting the tax on electricity consumption for the development of REs based on budget status leads to the best policy result for a desired installed capacity development without any negative social effects and financial crises.

Abstract This paper presents an unsteady, two-dimensional numerical model of a hybrid solar power generation system (STEG) that integrates photovoltaic (PV) and thermoelectric generator (TEG) technologies to harvest more solar energy under typical environmental and operating conditions. The model takes into account solar irradiation, wind speed and ambient temperature in addition to convective and radiative heat losses from the front and rear surfaces of the system. The governing equations are discretized using finite volume method and a fully implicit formulation is adopted for the time dependent terms. Results of each part of the numerical modeling were compared with the available experimental measurements and satisfactory agreements were observed. In addition, the effects of wind speed and ambient temperature, PN couples' height and external load resistance variations on the STEG performance are investigated. A monocrystalline photovoltaic cell (PV) is used and a commercial TE module is selected. Meteorological information of the 6th of July for the city of Shiraz, Iran with a latitude of 29.39 ° N are used which contain ambient air temperature and average wind speed. Computation is made with the developed code for a duration of 24 h. Results show that adding TE module at the back of PV can improve PV efficiency and PV electrical output power by 0.59% and 5.06%, respectively. Furthermore, it is found that as the wind speed increases, the PV efficiency improves and the TEG efficiency decreases. Also, a rise in the ambient temperature causes the PV efficiency to decrease but increases the TEG efficiency.

Abstract In this study, the combustion, performance, and emission results of the HCCI engine under different fuel and engine parameters conditions were examined experimentally and statistically. Engine speed, excess air ratio, and fuel types with different fusel oil concentrations were used as variable parameters. The engine speed was determined as 1000 and 1200 rpm, excess air ratio 1.7 and 2.1, and fusel oil ratio in fuel was determined as 15% and 30%. When the HCCI engine was operated with these input parameters, the effective torque indicated thermal efficiency, maximum pressure increase rate, COVimep, HC, CO, and NOx values were examined. Experiments were carried out in line with the determined experimental series, and the data obtained were analyzed. Optimization has been made to determine the optimum input parameters by inputting the targeted response parameters from the HCCI engine. After the optimization study, it was concluded that the optimum response parameters, engine speed was 1262.44 rpm, excess air ratio was 1.91631, and was obtained by using F30 fuel. Under optimum input parameters, the effective torque is 5.751 Nm, ITE 34.089%, MPRR 7.257%, COVimep 4.009%, CA50 7 ° CA, HC 454.185 ppm, CO 0.0727%, and NOx 0.000169486 ppm.

Abstract This study examines energy consumption of inputs and output used in kiwifruit production, and to find relationship between energy inputs and yield in Mazandaran, Iran. For this purpose, the data were collected from 86 kiwifruit orchards which were selected based on random sampling method. The results indicated that total energy inputs were 30285.62 MJ ha −1 . About 47% of this was generated by total fertilizer including farmyard manure, 28% from diesel fuel and machinery. About 70% of the total energy inputs used in kiwifruit production was indirect while only about 30% was direct. Econometric estimation results revealed that energy inputs of human labour, water for irrigation, total fertilizer and machinery contributed significantly to the yield. The impact of human labour energy (0.17) was found the highest among the other inputs in kiwifruit production. The results also showed that direct, indirect and renewable and non-renewable, energy forms had a positive impact on output level. Cost analysis showed that total cost of kiwifruit production was obtained as 6063.81 $ ha −1 . The productivity (4.05 kg $ −1 ) was obtained by dividing kiwifruit yield by total production cost.

Abstract Soybean residue (SR) is a main solid waste produced during the extraction of soybean oil with bulk volume. In addition to the use as vegetable protein feed, SR could also be used as feedstock for producing biofuels and carbon materials via pyrolysis. In this study, the pyrolysis behaviors of SR at varied temperatures and heating rates were investigated. The results show that the pyrolysis of the organic components in SR could reach completion even at 500 °C, due to the lower thermal stability of the organic component than that in the typical biomass. This also leads to the bio-oil with little heavy organics and also low carbon content of the resulting biochar, as the organic components decomposed to a significant extent while the charring reactions were insignificant. This leads to the biochar with low heating value and low energy yield when compared with that in the pyrolysis of typical biomass. In addition, the high content of proteins, amino acids and other nitrogen-containing nutrients make the SR derived bio-oil nitrogen-rich and a significant portion of nitrogen could also be retained in the biochar. These specialties have to be considered during their applications as either biofuels or functional carbon materials.

Abstract Renewable energy resources and technologies, especially solar thermal and photovoltaic systems, can provide advantageous and clean options for meeting electrical demands. The location and sizing of photovoltaic systems affect the system losses significantly. Here, a new hybrid framework for the optimal location and size for an off-grid solar/hydrogen energy system is proposed using an improved heuristic approach: improved harmony search and geographic information system (GIS). To determine the appropriate capacity and location for a grid-independent photovoltaic scheme in rural areas, a GIS module is used subject to several criteria: social, economic, technical, and environmental. The life cycle cost, the main objective function, is minimized and employed to assess the viability of the stand-alone photovoltaic scheme with hydrogen storage accounting for the reliability of the scheme. The system reliability is measured with the parameter loss of power supply probability. The proposed framework is useful, and is applied here to an actual case study in Iran for illustrative purposes. To validate the effectiveness of the proposed algorithm, the results obtained by proposed algorithm are compared with those of harmony search algorithm-based geographic information systems. The results of the simulation show the advantages of utilizing the proposed framework, based on improved harmony search and geographic information systems, for a grid-independent photovoltaic scheme considering both power quality and cost in remote and island areas.