Kamil Kaygusuz

Renewable energy potential and utilization in Turkey.

Abstract Renewable energy sources have been important for humans since the beginning of civilisation. For centuries, and in many ways, biomass has been used for heating, and cooking. Many centuries ago, mankind was already utilizing the clearly visible power of water for mechanical drive purposes, as was also the case with wind. Today, water mills are still used in our villages, although their numbers are going to diminish. On the other hand, Turkey is an energy importing country with more than half of the energy requirement being supplied by imports, and air pollution is becoming a great environmental concern in the country. In this regard, renewable energy resources appear to be one of the most efficient and effective solutions for sustainable energy development and environmental pollution prevention in Turkey. Turkeys geographical location has several advantages for extensive use of most of the renewable energy sources. Because of this and the fact that it has limited fossil fuel resources, a gradual shift from fossil fuels to renewables seems to be serious and the sole alternative for Turkey. This article presents a review of recent studies on the renewable energy sources, their potential and present use in Turkey.

Thermal energy storage system using stearic acid as a phase change material

Abstract The thermal performance and phase change stability of stearic acid as a latent heat energy storage material has been studied experimentally. The thermal performance and heat transfer characteristics of the stearic acid were tested and compared with other studies given in the literature. In the present study, parameters such as transition times, temperature range and propagation of the solid–liquid interface as well as the effect of the heat flow rate on the phase change stability of stearic acid as a phase change material (PCM) were studied. The experimental results showed that the melting stability of the PCM is better in the radial direction than in the axial direction. The variation in the melting and solidification parameters of the PCM with the change of inlet water temperature is also studied. We observed that while the heat exchanger tube is in the horizontal position, the PCM has more effective and steady phase change characteristics than in the vertical position. The heat storage capacity of the container (PCM tube) is not as good as we expected in this study and the average heat storage efficiency (or heat exchanger effectiveness) is 50.3%. This indicates that 49.7% of the heat is actually lost somewhere.

Thermal performance of palmitic acid as a phase change energy storage material

Abstract Experimental investigation of palmitic acid as a phase change material (PCM) for energy storage has been conducted in this study. The performance and heat transfer characteristics of a simple tube-in-tube heat exchanger system were studied, and the obtained results were compared with other studies given in the literature. The present study included some parameters, such as transition times, temperature range and propagation of the solid–liquid interface, as well as the heat flow rate characteristics of the employed cylindrical tube storage system. The experimental results show that the melting front moves in the radial direction inward, as well as in the axial direction from the top toward the bottom of the PCM tube. It was observed that the convection heat transfer in the liquid phase plays an important role in the melting process. The flow rate and inlet temperature of the heat transfer fluid to the PCM tube in the experimented range has an insignificant effect on the phase change processes. On the other hand, the melting and solidification times of the PCM can be reduced significantly by placing the tube containing the PCM in a horizontal position rather than a vertical one. The heat storage capacity of the PCM tube is not as good as we expected in this study, and the average heat storage efficiency (or heat exchanger effectiveness) is 53.3. It means that 46.7% of the heat actually is lost somewhere.

Biomass energy potential in Turkey

Biomass energy includes fuelwood, agricultural residues, animal wastes, charcoal and other fuels derived from biological sources. It currently accounts for about 14% of world energy consumption. Biomass is the main source of energy for many developed and developing countries. In Turkey energy wood is available in the form of forest chips, fuelwood, wood waste, wood pellets, and it is also produced to a very limited extent from willow crops in short rotation forestry. The major part of wood harvested in the forest area (approximately 10million ha) ends up as energy wood directly or indirectly after having been used for other purposes first. An overview of biomass potential and utilization in Turkey is presented. In 1999, the biomass share of the total energy consumption of the country is 10 percent. The level of fuelwood use together with that of other agricultural and animal wastes is compared with the commercial energy use within the countrys global energy balance. The possibilities of increasing fuelwood production through afforestation programmes and substitution for commercial fuels are discussed. Biogas utilization in the rural regions is also reviewed, emphasizing its possible contribution.

The Viability of Thermal Energy Storage

With rising energy costs and an increasing demand for renewable energy sources, thermal energy storage (TES) systems are becoming an interesting option. TES is a key component of any successful thermal system and a good TES should allow minimum thermal energy losses. In this study, various ways of thermal conservation are outlined and discussed, both theoretical and experimental. In this respect, the TES systems and their practical applications and some selection criteria have also been given.

Thermal performance of myristic acid as a phase change material for energy storage application

Thermal performance and phase change stability of myristic acid as a latent heat energy storage material has been studied experimentally. In the experimental study, the thermal performance and heat transfer characteristics of the myristic acid were tested and compared with other studies given in the literature. In the present study is included some parameters such as transition times, temperature range, and propagation of the solid–liquid interface as well as heat flow rate effect on the phase change stability of myristic acid as a phase change material (PCM). The experimental results showed that the melting stability of the PCM is better in the radial direction than the axial direction. The variety of the melting and solidification parameters of the PCM with the change of inlet water temperature is also studied. The results show that the better stability of the myristic acid was accomplished at low inlet water temperature compared with the obtained results at high inlet water temperature. We also observed that while the heat exchanger tube is in the horizontal position, the PCM has more effective and steady phase change characteristics than in the vertical position. The heat storage capacity of the container (PCM tube) is not as good as we expected in this study and the average heat storage efficiency (or heat exchanger effectiveness) is 54%. It means that 46% of the heat acrually lost somewhere.

Some fatty acids used for latent heat storage: thermal stability and corrosion of metals with respect to thermal cycling

The present study includes thermal stability of some fatty acids as phase change materials (PCMs). The selected fatty acids were stearic, palmitic, myristic and lauric acid with melting temperatures between 40–63°C and industrial-grade with 90–95 % purity. Latent heat storage capacity and phase transition temperature of the PCMs were determined by Differential Scanning Calorimetry (DSC) technique as a function of after repeated thermal cycles such as 40, 410, 700 and 910. The present work also comprises the investigation of corrosion resistance of some construction materials to the fatty acids over a long period. The containment materials tested were stainless steel (SS 304 L), carbon steel (steel C20), aluminium (Al) and copper (Cu). Gravimetric analysis as mass loss (mg/cm2), corrosion rate (mg/day) and a microscopic or matellographic investigation were performed for corrosion tests after 910 thermal cycles. DSC measurements showed that all fatty acids investigated as PCMs have a good thermal stability as a function of latent heat and phase transition temperature range for an actual middle-term thermal energy storage utility. However, in long-term solar thermal applications, the palmitic acid and myristic acid may be considered more suitable PCMs than the others. From the gravimetric and metallographic results, it can be concluded that stainless steel (SS 304L) with chromium oxide (Cr2O3) surface layer and Al with aluminium oxide (Al2O3) surface layer are essentially compatible with the investigated fatty acids. Carbon steel (Steel C20) and Cupper (Cu) are only preferantially compatible with PCMs.

Renewable energy and sustainable development in Turkey

Achieving solutions to environmental problems that we face today requires long-term potential actions for sustainable development. In this regard, renewable energy resources appear to be the one of the most efficient and effective solutions. So clean, domestic and renewable energy is commonly accepted as the key for future life for Turkey. Turkeys geographical location has several advantages for extensive use of most of these renewable energy sources. Because of this and the fact that it has limited fossil fuel resources, a gradual shift from fossil fuels to renewables seems to be serious and the sole alternative for Turkey. This article presents a review of the present energy situation and sustainability, technical and economical potential of renewable energy sources and future policies for the energy sector in Turkey. Also, potential solutions to current environmental problems are identified along with renewable energy technologies. Throughout the paper several problems relating to renewable energy sources, environment and sustainable development are discussed from both current and future perspectives. The renewable energy potential of the country and their present use are evaluated here based on the available data. The present study shows that there is an important potential for renewables in Turkey.

Environmental impacts of energy utilisation and renewable energy policies in Turkey

Abstract This paper extensively concentrates on energy and environmental impacts only. Energy utilisation and its major environmental impacts are discussed from the standpoint of sustainable development, including anticipated patterns of future energy use and subsequent environmental issues in Turkey. Several aspects relating to energy utilisation, renewable energy, energy efficiency, environment and sustainable development are examined from both current and future perspectives. Turkey is an energy-importing country; more than half of the energy requirement has been supplied by imports. Domestic oil and lignite reserves are limited and lignites are characterised by high ash, sulphur and moisture content. Due to increasing energy consumption, air pollution is becoming a great environmental concern for the future of the country. In this regard, renewable energy resources appear to be the one of the most efficient and effective solutions for sustainable energy development and environmental pollution preventation in Turkey. Turkeys geographical location has several advantages for extensive use of most of these renewable energy sources.

Thermal and heat transfer characteristics in a latent heat storage system using lauric acid

The thermal and heat transfer characteristics of lauric acid during the melting and solidification processes were determined experimentally in a vertical double pipe energy storage system. In this study, three important subjects were addressed. The first one is temperature distributions and temporal temperature variations in the radial and axial distances in the phase change material (PCM) during phase change processes. The second one is the thermal characteristics of the lauric acid, which include total melting and total solidification times, the nature of heat transfer in melted and solidified PCM and the effect of Reynolds and Stefan numbers as inlet heat transfer fluid (HTF) conditions on the phase transition parameters. The final one is to calculate the heat transfer coefficient and the heat flow rate and also discuss the role of Reynolds and Stefan numbers on the heat transfer parameters. The experimental results proved that the PCM melts and solidifies congruently, and the melting and solidification front moved from the outer wall of the HTF pipe (HTFP) to the inner wall of the PCM container in radial distances as the melting front moved from the top to the bottom of the PCM container in axial distances. However, it was difficult to establish the solidification proceeding at the axial distances in the PCM. Though natural convection in the liquid phase played a dominant role during the melting process due to buoyancy effects, the solidification process was controlled by conduction heat transfer, and it was slowed by the conduction thermal resistance through the solidified layer. The results also indicated that the average heat transfer coefficient and the heat flow rate were affected by varying the Reynolds and Stefan numbers more during the melting process than during the solidification process due to the natural convection effect during the melting process.