Sedat Keleş

Energy utilization, environmental pollution and renewable energy sources in Turkey.

In this study, energy utilization 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 utilization, 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 the lignites are characterised by high ash, sulfur and moisture content. Because of increasing energy consumption, environmental pollution is becoming a serious problem in the future for 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 these renewable energy sources. Especially hydropower, biomass, geothermal, solar and wind energy should be considered and seriously supported by governments and private sectors. � 2003 Elsevier Ltd. All rights reserved.

Comparing multipurpose forest management with timber management, incorporating timber, carbon and oxygen values: A case study

Abstract This paper comparatively examines two forest management planning approaches: multipurpose forest management and traditional timber management, with carbon, timber and oxygen production objectives in mind. The effects of both approaches on carbon and oxygen values were estimated with an oxygen and carbon flow matrix, while timber production was modelled through a growth and yield model. The estimated values were simultaneously integrated into a linear programming model developed for this study. The objective was to maximize the net present value (NPV) of the profits of timber, oxygen and carbon under the constraints of an even flow of timber production and ending forest inventory for each planning approach. The results showed that the ecological and environmental regulations in multipurpose management substantially decreased the NPV of timber production even though they increased the NPV of carbon and oxygen flow. The results also indicated that over a 100 year planning horizon the total NPV of all forest ecosystem values including carbon, timber and oxygen is almost the same (only 1.9% reduction in multipurpose management approach) in both management approaches. Although multipurpose management creates more NPV of carbon and oxygen than timber management does, the latter provides better results in terms of timber production. It is therefore important to take into account the NPV of all apparent and quantifiable forest values in preparing forest management plans, particularly in developing new management planning approaches.

Pyrolysis of Woody Biomass for Sustainable Bio-oil

Abstract Fast pyrolysis utilizes biomass to produce a product that is used both as an energy source and a feedstock for chemical production. Considerable efforts have been made to convert wood biomass to liquid fuels and chemicals since the oil crisis in the mid-1970s. Virtually any form of biomass can be considered for fast pyrolysis. The effect of the wood composition and structure, heating rate, and residence time during pyrolysis on the overall reaction rate and the yield of the volatiles are discussed. In this study, fast pyrolysis of hazelnut cupula was investigated experimentally in a fixed-bed reactor under various conditions. Hazelnut cupula, an agricultural by-product, was selected as raw material for pyrolysis experiments. The fixed-bed fast pyrolysis experiments have been conducted on a sample of hazelnut cupula in a fixed-bed reactor to determine, in particular, the effects of pyrolysis temperature, heating rate, particle size, and sweep gas flow rate on the pyrolysis product yields. The reactor was heated at a heating rate of 200°C per minute to a pyrolysis temperature of 400, 500, 600, and 700°C. Experiments show that pyrolysis yields and conversion efficiencies depended mainly on pyrolysis temperature and 600°C was the most suitable for decomposition of the hazelnut cupula to reach a maximum oil yield.

Effect of aspect, tree age and tree diameter on bark thickness of Picea orientalis

Abstract The volume of bark is a function of bark thickness and tree diameter, thus bark and tree volume calculations depend on accurate determination of bark thickness. Bark thickness is affected by a number of inherent and external factors. The purpose of this study was to examine the factors affecting bark thickness and to derive models predicting bark thickness for Picea orientalis (L.) Link. This study indicated that bark thickness at breast height was strongly correlated with geographical aspect, tree age and diameter classes, and bark thickness increased as tree age or diameter class increased in sunny or shady aspect. Diameter over bark at breast height explained 50% of the variations in double bark thickness at breast height on shady aspects and 68% of the variations in double bark thickness of P. orientalis at breast height on sunny aspects. By adding tree age to the functions, the coefficient of determination increased by 1–2%. Thus, not only tree ages and diameters, but also the aspect in which trees grow should be taken into account to calculate the amounts of wood and bark in P. orientalis.

The Role of Biomass in Greenhouse Gas Mitigation

Abstract Biomass can play a dual role in greenhouse gas mitigation related to the objectives of the UNFCCC, i.e., as an energy source to substitute for fossil fuels and as a carbon store. However, compared to the maintenance and enhancement of carbon sinks and reservoirs, it appears that the use of biomass has so far received less attention as a means of mitigating climate change. Modern biomass options offer significant, cost-effective and perpetual opportunities toward meeting emission reduction targets while providing additional ancillary benefits. Moreover, via the sustainable use of the accumulated carbon, biomass has the potential for resolving some of the critical issues surrounding long-term maintenance of biotic carbon stocks. In the case of Turkey, energy consumption and environmental pollution are increasing rapidly due to its economic growth. As for the energy consumption, in parallel to the demand for heat and electricity, greenhouse gas emissions (GHGs) from energy use increase accordingly. In this regard, biomass and other renewables are becoming an attractive solution to the GHG mitigation for Turkey and other countries throughout the world. Finally, wood products can act as substitutes for more energy-intensive products, can constitute carbon sinks, and can be used as biofuels at the end of their lifetime.

Use of Biomass as a Transitional Strategy to a Sustainable and Clean Energy System

Abstract Attempts to establish regenerative energy sources are still being rejected. Only since the oil crises, have regenerative energy sources been included in energy policy discussions. Compared with conventional sources of energy, used a much longer period of time, there appears to be a considerable lack of knowledge on regenerative sources of energy. It is another aspect that present-day supply of energy is based on a centralized structure. In contrast, renewable sources of energy, such as irradiation and energies arising from it like wind, ambient heat, and bioenergy, have a very low energy density and therefore require a decentralized supply structure. In addition, fluctuations caused by the seasons and different weather conditions, and the fact that renewable energy sources are tied to a certain place, are another challenge to this new structure of supply. On the other hand, with more than 26% of the state covered by forests, Turkey is a country rich in timber, with a considerable yield of wood. It is therefore obvious to exploit this national potential for energy production. However, only a short time ago, increasing efforts were started for utilizing biomass for electric power generation and as raw material for high-quality gaseous and liquid fuels. For this purpose, conventional technologies, such as gas turbines, are partly being used, which work highly efficiently, with low investments even today. In order to use new technologies for electric power generation, the mainly solid biomass has to be converted into liquid or gaseous energy resources by means of bio-conversion.

Spatiotemporal Changes in Landscape Pattern in Response to Afforestation in Northeastern Turkey: A Case Study of Torul

Abstract Monitoring and understanding of land use/forest cover dynamics as well as the factors affecting the changes in land use/forest cover are necessary for the sustainable management of natural resources. This study analyzes the spatial and temporal changes in land use and forest cover patterns in a typical mountain forest area in the Torul State Forest Enterprise area of Northeastern Turkey. The investigation evaluates the temporal changes of the spatial structure of forest conditions through the spatial analysis of forest-cover type maps from 1984 and 2005 using GIS and FRAGSTATS. The evidence presented here showed that there were drastic changes in the temporal and spatial dynamics of land use/forest cover, and between 1984 and 2005 there was a net increase of 19.9% in total forested area. Productive forest area increased by 3161 ha, although degraded forest area increased 9216 ha. In examining the changes of crown closure and development stages of the forest ecosystem during the study period, the forest stand area with low crown closures increased. The regenerated area increased because of regeneration activities while the other development stages were left to grow to older development stages in the period. These results regarding the crown closure and development stage show that forest quality has increased, and this is partly due to emigration of the rural population in Torul. In terms of spatial configuration, the landscape structure in Torul, the State Forest Enterprise area, changed substantially over the 21-year study period, resulting in fragmentation of the landscape as indicated by large patch numbers and smaller mean patch sizes, owing to heavy timber subtraction, illegal cutting, and uncontrolled stand treatments.

Forest optimisation models including timber production and carbon sequestration values of forest ecosystems: a case study.

The integration of carbon sequestration value of forest ecosystems into forest management planning models has become increasingly important in sustainable forest management. This study analyses the economic effects of different minimum cutting ages on timber and carbon sequestration values for a Scots pine forest clumped mainly in older age classes in northeast Turkey. The analysis is performed by formulating three optimisation models. The objective of each model is to maximise net present value (NPV) of harvested timber, net present value of carbon sequestration and the total net present value of timber production and carbon sequestration, respectively. Results showed that increasing the minimum cutting ages by 10 years increased the NPV of timber by 10.5%. However, the current minimum cutting ages were optimal for maximizing the NPV of carbon and the sum of the NPV of timber and carbon benefits. In addition, the model outputs were found to be quite sensitive to unit carbon prices.

Sustainable Agriculture and the Production of Biomass for Energy Use

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The effects of land-use and land-cover changes on carbon storage in forest timber biomass: a case study in Torul, Turkey

This study presents spatial and temporal changes of carbon storages of forest timber biomass in a typical forest management unit of the northeastern part of Turkey. The effects of land-use and land-cover changes on the amount of carbon storage are analyzed. Temporal changes of carbon storage of the area were estimated using forest inventory data. The spatial distribution of carbon densities was mapped using Geographic Information Systems (GISs). As an overall change between 1984 and 2005, there was a net increase of 12,379 ha in forested areas. The results indicated that the total amount of carbon stored in the above- and belowground forest ecosystems increased nearly by 47% from one period to the next mainly due to increase of forest area and the quality of forest ecosystem structure.