Gunnur Kocar

The potential of biogas energy

Biogas technology has been known about for a long time, but in recent years the interest in it has significantly increased, especially due to the higher costs and the rapid depletion of fossil fuels as well as their environmental considerations. The main objective of the present study is to investigate the potential of biogas energy in the 15 European Union (EU) countries and in Turkey, which is seeking admission to the EU and is trying to meet EU environmental standards. Biogas energy potential of the 15 EU countries is estimated to be about 800 PJ. Besides this, Turkeys annual animal waste potential is obtained to be about 11.81 million tons with a biogas energy equivalent of 53.6 PJ. It is expected that this study will be helpful in developing highly applicable and productive planning for energy policies towards the optimum utilization of biogas energy.

Comparison of Vacuum Cooling with Conventional Cooling for Purslane

Vacuum cooling technology is a proven technology widely applied on precooling of leafy vegetables, mushrooms, baked goods, fish, sauces, cooked foods, and particulate foods. Vacuum cooling is known as a rapid evaporative cooling technique for moist and porous products. Vacuum cooling has some advantages, such as shortened processing time, extended product shelf life, and improved product quality and safety. The aim of this paper is to apply the vacuum cooling technique to the cooling of purslane and show the pressure effect (for 0.7 kPa, 1 kPa, 1.5 kPa) on the cooling time and temperature decrease. Another purpose of this article is to compare conventional cooling (cooling by refrigerator) with vacuum cooling. It has been seen that purslane can be cooled much more rapidly and efficiently with vacuum cooling than with conventional cooling.

A Heuristic Approach to Design and Analyze the Hybrid Electric Vehicle Powertrain and Energy Transmission Systems

The Hybrid Electric Vehicle (HEV) powertrain, and an efficient power conversion and energy transmission process, are significant factors to reduce conventional fuel consumption and vehicle gas emission. The scale of gas emission of an HEV depends on an efficient design process for the powertrain and an optimal energy management system. Therefore, this paper models an efficient powertrain and energy transmission process for both series and parallel HEVs, which can contribute to the emission reduction process. Different power conversion stages, energy transmission paths, emissions, and a systems response corresponding to the driver’s profile are analyzed systematically. Finally, the emission of the proposed system is compared with the European standard of vehicle gas emission .

Economic challenges of hybrid microgrid: An analysis and approaches for rural electrification

This paper focuses on the integration of three renewable resources: biogas, wind energy and solar energy, utilizing solar PV panels, a biogas generator, and a wind turbine, respectively, to analyze the technical and economic challenges of a hybrid micro-gird. The integration of these sources has been analyzed and optimized based on realistic data for a real location. Different combinations of these sources have been analyzed to find out the optimized combination based on the efficiency and the minimum cost of electricity (COE). Wind and solar energy are considered as the primary sources of power generation during off-peak hours, and any excess power is used to charge a battery bank. During peak hours, biogas generators produce power to support the additional demand. A business strategy to implement the integrated optimized system in rural areas is discussed.

Influence of thermal and alkali pretreatment to solubilisation and biomethane production of garden waste

The objectives of this study were to determine the effect of pretreatment to the garden wastes under thermal and alkali conditions and to evaluate biochemical methane potential. In thermal pretreatment different temperatures and application times were examined and solubilisation improved by heating. Soluble chemical oxygen demand (sCOD) concentration upgraded by increasing temperature with different time intervals. 90°C and 2–hour pretreatment time enabled maximum solubilisation of COD for garden waste. For carbohydrate solubilisation, 50°C and 8–hour application time showed the best performance. Alkali pretreatment also stimulated solubilisation of COD, carbohydrates and total nitrogen which concluded with biochemical methane potential tests. Alkali pretreatment (1% NaOH) increased the overall biomethane production by about 30% compared to the garden wastes without pretreatment. According to this study, the highest methane yield (397.7 ml/gVS) was obtained with 1% NaOH pretreatment to garden waste without pH adjustment.

Exergy assessment of biodiesel production process: application

This study deals with the exergetic assessment of the biodiesel production process from canola oil (CAO). In this regard, exergy analysis is applied to the process of methyl ester obtained from CAO first. The energy and exergy relations used in the analysis are presented next. The performance of the whole biodiesel system along with its main components is then evaluated using energy and exergy analysis methods. Finally, the biodiesel production from CAO is assessed using these analysis methods, while the results obtained are discussed. The overall mean energy and energy efficiencies of the biodiesel production process in the period studied are found to be 96·50 and 75·60% respectively. It is expected that the results of this study will be helpful in developing highly applicable and productive planning for biodiesel production.