Browsing by Author "Melikoğlu, Mehmet"

Now showing 1 - 11 of 11

Citation - WoS: 198
Citation - Scopus: 275
Analysing Global Food Waste Problem: Pinpointing the Facts and Estimating the Energy Content
(de Gruyter Open Ltd, 2013) Melikoglu, Mehmet; Lin, Carol Sze Ki; Webb, Colin; Energy Systems Engineering
Food waste is a global problem. Each year food worth billions of dollars is wasted by the developed economies of the world. When food is wasted, the problem does not end at that point. More than 95% of the food waste ends at landfill sites, where converted into methane, carbon dioxide and other greenhouse gasses by anaerobic digestion. The impact of food waste to climate change is catastrophic. Food waste problem tends to increase in next 25 years due to economic and population growth mainly in Asian countries. In addition, when food wastes buried at landfill sites their energy content is lost. Although food waste is a huge problem, its global size and extent has recently become a hot topic in the academic community. This paper summarises the size of the global food waste problem together with the estimation of the amount of energy lost when food wastes dumped at landfill sites. Calculations in this study also revealed that energy lost at landfill sites equals to 43% of the delivered energy used for the preparation of foods in the US, 37% of the hydroelectric power generation of Japan, and more than 100% of the current annual renewable energy demand of UK industries.
Citation - WoS: 13
Citation - Scopus: 15
Bioethanol Production and Potential of Turkey
(Gazi Univ, Fac Engineering Architecture, 2011) Melikoglu, Mehmet; Albostan, Ayhan; Energy Systems Engineering; Energy Systems Engineering
The ever increasing demand in global energy consumption makes it inevitable for the development of new energy resources. Turkey imports nearly all of its petroleum and this causes major economical problems. In Turkey, a major cereal producer, production of energy crops will decrease the dependence of petroleum and greenhouse gas emissions. In this context, bioethanol production in Turkey becomes a major alternative to petroleum. According to the results find in this study, with the current agricultural output, none of the crops can be adequate for bioethanol production even 100% of crop harvests were utilized. However, with 4% and 7% of current wheat harvest bioethanol required for the production of E5 and E10 can be achieved. In addition, by utilizing the unused land available for agriculture and planting potato, sugar beet, and wheat (each 100%), 5.8, 8.7 and 13.7 billion litres of bioethanol can be produced and this production will be more than enough to supply Turkey's current demand for gasoline.
Citation - WoS: 36
Citation - Scopus: 47
Demand Forecast for Road Transportation Fuels Including Gasoline, Diesel, Lpg, Bioethanol and Biodiesel for Turkey Between 2013 and 2023
(Pergamon-elsevier Science Ltd, 2014) Melikoglu, Mehmet; Energy Systems Engineering
In Turkey, more than 90% of passengers and goods are transported by roads. In order to flow this immense traffic nearly 2.7 million m(3) of gasoline, 11.5 million m(3) of diesel, and 5.2 million m(3) of liquefied petroleum gas (LPG) was consumed in 2011. Starting from 2013, Turkey plans to blend biofuels to gasoline and diesel gradually reaching to 10% (volume) by 2020. Turkey's economy has been growing at unprecedented rates since 2003. As a result, both diesel and LPG consumption reached to record levels. Yet, gasoline demand decreased almost linearly in the same period. Accordingly, forecasting road transportation fuel demand becomes more difficult and yet more important than ever before. Gasoline, diesel, LPG, bioethanol and biodiesel demand has been forecast for the first time in this study using semi-empirical models in the view of Turkey's Vision 2023 goals, Energy Market Regulatory Authority targets, and European Union directives. The models suggested that in 2023, annual gasoline consumption in Turkey could decrease below 2.0 million m(3), whereas, diesel and LPG consumption could rise to 16.4 and 8.8 million m(3), respectively. Consequently, 0.3 million m(3) of bioethanol and 1.4 million m(3) biodiesel could be required to fulfil the official targets in 2023. (C) 2013 Elsevier Ltd. All rights reserved.
Citation - WoS: 38
Citation - Scopus: 38
Hydropower in Turkey: Analysis in the View of Vision 2023
(Pergamon-elsevier Science Ltd, 2013) Melikoglu, Mehmet; Energy Systems Engineering
Turkey is a recently developed country, a regional power in the Middle East and an economic powerhouse of the region. Turkey's electricity demand is continuously increasing due to fast economic growth coupled with the country's vibrant young population. It is envisaged that this demand would keep on increasing almost exponentially in the next decade according to the recently avowed Vision 2023 agenda. According to which, the Turkish government ambitiously wants to provide 30.0% of the country's electricity demand from renewable energy sources by 2023. Turkey has vast renewable energy potential including hydro, geothermal, solar and wind. However, historically there is only one playmaker that is hydropower. Thus a detailed review of the current status and future prospects of Turkish hydropower market is urgently needed to generate a roadmap for the Vision 2023 agenda. This paper was intended to provide that vital information. Currently, more than 25.0% or 57.5 TWh of the country's electricity demand is supplied from hydropower. According to official projections this would increase to approximately 116.0 TWh in 2023. In this study, hydropower's supply rate of Turkey's annual electricity demand was assessed based on the official projections and a forecast was generated. Results showed that between 22.0% and 27.0% of Turkey's annual electricity demand should be supplied from hydropower in 2023. Therefore, between 22.5 TWh and 45.0 TWh of electricity should be generated from renewable energy sources other than hydropower to provide a total of 30.0% renewable energy based electricity generation in 2023. (C) 2013 Elsevier Ltd. All rights reserved.
Citation - WoS: 60
Citation - Scopus: 68
Kinetic Studies on the Multi-Enzyme Solution Produced Via Solid State Fermentation of Waste Bread by aspergillus Awamori
(Elsevier Science Bv, 2013) Melikoglu, Mehmet; Lin, Carol Sze Ki; Webb, Colin; Energy Systems Engineering
The aim of this study was kinetic analysis of the multi-enzyme solution produced from waste bread via solid state fermentation by Aspergillus awamori. It was found that at normal temperature for hydrolysis reactions, 60 degrees C, the activation energies for denaturation of A. awamori glucoamylase, 176.2 kJ/mol, and protease, 149.9 kJ/mol, are much higher than those for catalysis of bread starch, 46.3 kJ/mol, and protein, 36.8 kJ/mol. Kinetic studies showed that glucoamylase and protease in the multi-enzyme solution should have at least two conformations under the two temperature ranges: 30-55 degrees C and 60-70 degrees C. Thermodynamic analysis showed that, deactivation of glucoamylase and protease in the multi-enzyme solution can be reversible between 30 degrees C and 55 degrees C, since Delta S is negative and Delta H is positive. On the other hand, for glucoamylase and protease, both Delta S and Delta H are positive between 60 degrees C and 70 degrees C. This means that the deactivation of both enzymes in the multi-enzyme solution is spontaneous in this temperature range. It was also found that the glucoamylase produced in the solid state fermentation of waste bread is more thermally stable than the protease in the mixture. Consequently, the protease had little or no effect on the stability of the glucoamylase. Furthermore, the half-life of the glucoamylase produced from waste bread pieces was much higher than that produced from wheat flour. This is an important finding because the mode of production, via solid state fermentation, appears to have increased the thermostability of the enzyme significantly. (C) 2013 Elsevier B.V. All rights reserved.
Citation - WoS: 64
Citation - Scopus: 72
Modelling and Simulation of a Hybrid Solar Heating System for Greenhouse Applications Using Matlab/Simulink
(Pergamon-elsevier Science Ltd, 2013) Kiyan, Metin; Bingol, Ekin; Melikoglu, Mehmet; Albostan, Ayhan; Energy Systems Engineering; Department of Mechanical Engineering
Solar energy is a major renewable energy source and hybrid solar systems are gaining increased academic and industrial attention due to the unique advantages they offer. In this paper, a mathematical model has been developed to investigate the thermal behavior of a greenhouse heated by a hybrid solar collector system. This hybrid system contains an evacuated tube solar heat collector unit, an auxiliary fossil fuel heating unit, a hot water storage unit, control and piping units. A Matlab/Simulink based model and software has been developed to predict the storage water temperature, greenhouse indoor temperature and the amount of auxiliary fuel, as a function of various design parameters of the greenhouse such as location, dimensions, and meteorological data of the region. As a case study, a greenhouse located in Sanhurfa/Turkey has been simulated based on recent meteorological data and aforementioned hybrid system. The results of simulations performed on an annual basis indicate that revising the existing fossil fuel system with the proposed hybrid system, is economically feasible for most cases, however it requires a slightly longer payback period than expected. On the other hand, by reducing the greenhouse gas emissions significantly, it has a considerable positive environmental impact. The developed dynamic simulation method can be further used for designing heating systems for various solar greenhouses and optimizing the solar collector and thermal storage sizes. (C) 2013 Elsevier Ltd. All rights reserved.
Citation - WoS: 70
Citation - Scopus: 86
Stepwise Optimisation of Enzyme Production in Solid State Fermentation of Waste Bread Pieces
(inst Chemical Engineers, 2013) Melikoglu, Mehmet; Lin, Carol Sze Ki; Webb, Colin; Energy Systems Engineering
When it is not consumed, bread presents a major source of food waste, both in terms of the amount and its economic value. However, bread also possesses the characteristics of an ideal substrate for solid state fermentation. Yet nearly all wasted bread ends up in landfill sites, where it is converted into methane by anaerobic digestion. Governments are finally taking action and, according to the EU Landfill Directive, for example, biodegradable municipal waste disposed into landfills must be decreased to 35% of 1995 levels, by 2020. Solid state fermentation of waste bread for the production of value added products is a novel idea, which could help with the achievement of this target. In this study, glucoamylase and protease production from waste bread pieces, via solid state fermentation, was investigated in detail. The optimum fermentation conditions for enzyme production were evaluated as, 20 mm particle size, 1.8 (w/w, db) initial moisture ratio, and duration of 144h. Under these conditions, glucoamylase and protease activities reached up to 114.0 and 83.2 U/g bread (db), respectively. This study confirms that waste bread could be successfully utilised as a primary raw material in cereal based biorefineries. (C) 2013 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
Citation - WoS: 56
Citation - Scopus: 61
Use of Waste Bread To Produce Fermentation Products
(Elsevier Academic Press inc, 2013) Melikoglu, Mehmet; Webb, Colin; Energy Systems Engineering
[No Abstract Available]
Citation - WoS: 61
Citation - Scopus: 78
Vision 2023: Assessing the Feasibility of Electricity and Biogas Production From Municipal Solid Waste in Turkey
(Pergamon-elsevier Science Ltd, 2013) Melikoglu, Mehmet; Energy Systems Engineering
Turkey imports most of its energy. However, according to the recently avowed Vision 2023 agenda the country also plans to produce 30% of its electricity demand from renewable energy sources by 2023. Meanwhile, each year around 25 million tonnes of municipal solid waste (MSW) is generated nationwide. Not only MSW pollutes the environment handling, processing and storage requires precious labour and capital. In that context, a synergistic solution can be created between MSW management and energy supply. In this study, economics and environmental impacts of electricity generation from MSW via (i) direct combustion and (ii) biogas harnessing in 81 cities of Turkey is analysed in detail for a period between 2012 and 2023. Firstly, it is estimated that nationwide 8500 GWh of electricity could have been generated by direct combustion of MSW in 2012. This is predicted to rise 9700 GWh in 2023. It is calculated that 3100 million m(3) of methane would be emitted from the landfills of Turkey in 2012. If no action taken this would rise to 3600 million m(3) in 2023. Furthermore, it is estimated that by capturing 25% of this methane via landfill bioreactors 2900 GWh or 0.5% of Turkey's annual electricity demand could be supplied in 2023. Simulations also showed that by realizing apposite landfill investments by 2023 annual energy savings worth 200-900 million (sic) could be generated from MSW. Consequently, this could lead to greenhouse gas emission savings up to 11.0 million tonnes of CO2 per annum. (C) 2012 Elsevier Ltd. All rights reserved.
Citation - WoS: 61
Vision 2023: Feasibility Analysis of Turkey's Renewable Energy Projection
(Pergamon-elsevier Science Ltd, 2013) Melikoglu, Mehmet; Energy Systems Engineering
Electricity consumption of Turkey at the year 2023 is estimated to be around 530,000 GWh. Turkey plans to supply 30% or 160,000 GWh of this demand from renewable energy sources according to the recently avowed government agenda Vision 2023. However, the current installed renewable energy capacity is around 60,000 GWh. Detailed literature analysis showed that only wind and solar energy potential in Turkey can solely supply this demand. In this study, two different scenarios were generated to analyse the cost and environmental impacts of supplying this demand. Scenario 1, which is derived from the official Vision 2023 targets, suggests supplying this demand from wind, solar, geothermal energy and hydropower. The total projected cost based on Scenario 1 is estimated to be $31.000 billion and annual greenhouse gas emissions of 1.05 million tonnes of CO2 equivalent. According to Scenario 2 or the contrary setup it is assumed that the required demand gap could not be supplied from new renewable energy investments but equally from coal and natural gas. The projected cost is estimated to be around $8.000 billion and annual greenhouse gas emissions at appalling 71.30 million tonnes of CO2 equivalent. Assuming carbon tax at the year 2023 to be $50 per tonne of CO2 emitted, supplying the demand from renewable energy sources according to Scenario 1 would generate savings worth nearly $2.175 billion from environmental taxes annually. Thus, making the payback time of the renewable energy investments less than 15 years. (C) 2012 Elsevier Ltd. All rights reserved.
Citation - WoS: 77
Citation - Scopus: 84
Vision 2023: Forecasting Turkey's Natural Gas Demand Between 2013 and 2030
(Pergamon-elsevier Science Ltd, 2013) Melikoglu, Mehmet; Energy Systems Engineering
Natural gas is the primary source for electricity production in Turkey. However, Turkey does not have indigenous resources and imports more than 98.0% of the natural gas it consumes. In 2011, more than 20.0% of Turkey's annual trade deficit was due to imported natural gas, estimated at US$ 20.0 billion. Turkish government has very ambitious targets for the country's energy sector in the next decade according to the Vision 2023 agenda. Previously, we have estimated that Turkey's annual electricity demand would be 530,000 GWh at the year 2023. Considering current energy market dynamics it is almost evident that a substantial amount of this demand would be supplied from natural gas. However, meticulous analysis of the Vision 2023 goals clearly showed that the information about the natural gas sector is scarce. Most importantly there is no demand forecast for natural gas in the Vision 2023 agenda. Therefore, in this study the aim was to generate accurate forecasts for Turkey's natural gas demand between 2013 and 2030. For this purpose, two semi-empirical models based on econometrics, gross domestic product (GDP) at purchasing power parity (PPP) per capita, and demographics, population change, were developed. The logistic equation, which can be used for long term natural gas demand forecasting, and the linear equation, which can be used for medium term demand forecasting, fitted to the timeline series almost seamlessly. In addition, these two models provided reasonable fits according to the mean absolute percentage error, MAPE %, criteria. Turkey's natural gas demand at the year 2030 was calculated as 76.8 billion m(3) using the linear model and 83.8 billion m(3) based on the logistic model. Consequently, found to be in better agreement with the official Turkish petroleum pipeline corporation (BOTAS) forecast, 76.4 billion m(3), than results published in the literature. (C) 2013 Elsevier Ltd. All rights reserved.