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This article assesses the current technical and economic potential of three bioenergy production systems (cassava ethanol, jatropha oil and fuelwood) in semi-arid and arid regions of eight sub-Saharan African countries. The results indicate that the availability of land for energy production ranges from 2% (1.3 Mha) of the total semi-arid and arid area in South Africa to 21% (12 Mha) in Botswana. Land availability for bioenergy production is restricted mainly by agricultural land use, but also by steep slopes and biodiversity protection. The current total technical potential for the semi-arid and arid regions of the eight countries is calculated to be approximately 300 PJ y−1 for cassava ethanol production, 600 PJ y−1 for jatropha biodiesel or 4000 PJ y−1 for fuelwood. The analysis of economic potentials shows that in many semi-arid regions, cassava ethanol, jatropha oil and fuelwood can compete economically with the reference energy sources. However, fuelwood, jatropha oil, and cassava ethanol production costs in most arid regions of sub-Saharan Africa are often above average national market prices of gasoline, diesel, and fuelwood. Nevertheless, for example, in arid Kenya 270 PJ could be produced annually with fuelwood at production costs of less than 3 US$ GJ−1. Despite high production costs, it is important to investigate and invest in sustainable bioenergy production in semi-arid and arid regions of sub-Saharan Africa because of its potential to drive rural economic and social development.

Abstract This study aims to analyze the innovation strategies for the green supply chain management with QFD (quality function deployment) multidimensionally. The novelty of the study is to define the criteria of green supply chain for each stage of QFD and propose a hybrid model by IVIF (interval-valued intuitionistic fuzzy) DEMATEL (decision making trial and evaluation laboratory) and IVIF MOORA (Multi-Objective Optimization by Ratio Analysis) respectively. The results demonstrate that understanding the customer expectations with customer relation management is the most important innovation strategy for the green supply chain management in energy industry with the consecutive stages of QFD whereas benchmarking the competitive market environment has relatively the last seat in the ranking. Hence, it is recommended that energy companies should have an effective customer relationship management. In this context, these companies should make a detailed analysis to learn what their customers directly expect from them. With the help of this issue, these companies should generate their product and services based on these expectations. Additionally, it is also stated that new service and product development is also essential for energy companies to improve their innovativeness. For this purpose, a research and development department should be created, and the qualified people should be employed. Additionally, different opinions should be collected from various parties, such as customers, employees, and suppliers. Since customers who are satisfied will prefer these companies, the energy companies can catch the opportunity to increase their market share.

The global demand for wood pellets used for energy purposes is growing. Therefore, increased amounts of wood pellets are produced from primary forestry products, such as pulp wood. The present analysis demonstrates that substantial amounts of alternative, low-value wood resources are available that could be processed into wood pellets. For three resources, test batches have been produced and tested to qualify for industrial pellet standards. These include: primary forestry residues from premerchantable thinning operations, secondary forestry residues from pole mills and post-consumer wood wastes from discarded wooden transport pallets. The total wood potential of these resources in the southeast of the U.S. (Florida, Georgia, North Carolina, South Carolina), was estimated to be 1.9 Tg y(-1) (dry) available at roadside (excluding transport cost) for 22 $ Mg-1 (dry) increasing to over 5.1 Tg y(-1) at 33 $ Mg-1 (dry). In theory, 4.1 Tg y(-1) pellets could be produced from the estimated potential. However, due to the geographically dispersed supply of these resources, the cost of feedstock supply at a pellet plant increases rapidly at larger plants. It is therefore not expected that the total potential can be processed into wood pellets at costs competitive with those of conventional wood pellets. The optimal size of a pellet plant was estimated at between 55 Gg y(-1) and 315 Gg y(-1) pellets depending on the location and feedstock supply assumptions. At these locations and plant sizes, pellets could be produced at competitive costs of between 82 $ Mg-1 and 100 $ Mg-1 pellets. (C) 2014 Elsevier Ltd. All rights reserved.

This paper assesses the learning potential of dedicated wood production systems to boost yields and reduce production costs. In particular, the paper analyses past trends and provides a future outlook of developments in dedicated wood production for three cases: eucalyptus production in Brazil, poplar production in Italy and willow production in Sweden. A main objective of this paper is to evaluate the extent to which experience curves can be devised for conventional woody plantation systems, and whether these can also be applied to short rotation cropping (SRC) production systems. For current average SRC production systems, Italian poplar shows the highest cost at 5.5 h GJ1 followed by Swedish willow at 4.4 h GJ1 and Brazilian eucalyptus is produced to the lowest costs at 2.8 h GJ1 . It was assessed to what extent production costs can be reduced per step in the production cycle and how this affects the minimum cost levels that can ultimately be achieved. Ultimate cost reduction could lead to delivered costs of 2.2 h GJ1 for poplar, 1.9 h GJ1 for willow and 1.9 h GJ1 for eucalyptus on better quality lands. Based on historic cost data and production trends, experience curves were applied providing progress ratios for poplar in Italy and eucalyptus in Brazil. Brazilian eucalyptus production follows a steeper slope (63–73%) than poplar in Italy (71–78%). The extent to, and rate at, which cost reductions can occur within the next 20 years were evaluated by combining current costs, minimum cost levels and progress ratios with ranges in European and global biomass demand projections. This shows that, at the assumed growth rates for biomass production in Europe and for global production, minimum cost levels can be reached within the next two decades for all cases.

AbstractAlthough our observing capabilities of solar‐induced chlorophyll fluorescence (SIF) have been growing rapidly, the quality and consistency of SIF datasets are still in an active stage of research and development. As a result, there are considerable inconsistencies among diverse SIF datasets at all scales and the widespread applications of them have led to contradictory findings. The present review is the second of the two companion reviews, and data oriented. It aims to (1) synthesize the variety, scale, and uncertainty of existing SIF datasets, (2) synthesize the diverse applications in the sector of ecology, agriculture, hydrology, climate, and socioeconomics, and (3) clarify how such data inconsistency superimposed with the theoretical complexities laid out in (Sun et al., 2023) may impact process interpretation of various applications and contribute to inconsistent findings. We emphasize that accurate interpretation of the functional relationships between SIF and other ecological indicators is contingent upon complete understanding of SIF data quality and uncertainty. Biases and uncertainties in SIF observations can significantly confound interpretation of their relationships and how such relationships respond to environmental variations. Built upon our syntheses, we summarize existing gaps and uncertainties in current SIF observations. Further, we offer our perspectives on innovations needed to help improve informing ecosystem structure, function, and service under climate change, including enhancing in‐situ SIF observing capability especially in “data desert” regions, improving cross‐instrument data standardization and network coordination, and advancing applications by fully harnessing theory and data.

SUMMARY This study searches the opportunity of use for potential flow methods in a flow analysis around a wind turbine blade and performance prediction of wind turbine rotors after a brief explanation about wind energy conversion systems, commercial use of these systems and aerodynamic research and development studies over them. Sorts of significant and accurate method for the understanding of general characteristics of flow around the turbine are potential flow methods such as lifting line, lifting surface, asymptotic acceleration potential and panel methods. They are analytical and numerical methods that can be translated into computer codes. The fastest growing energy resource today is wind power. Worldwide electricity generation capacity from wind has risen from 3700 megawatts (MW) in 1994 to 4900 MW by the end of 1995. The rate of increase in installed capacity has been %150 from 1990 to the beginning of 1996 and this corresponds to an annual average increase of %20. This rapid growth in utility and continuous technological development in conversion systems promises a significant alternative of an energy resource for several countries and regions. Wind power used to be interesting as it was a renewable resource and the environmental impact of the conversion process has been minimum comparing with the other technologies. But the main reason for widespread use of this technology today is the decrease of capital and generation costs of the conversion systems, becoming competitive with conventional technologies. Also implementation of the full social cost concept by means of CO2 taxes or supports has led the commercialization of this clean technology, especially in industrial countries. European wind power industry has achieved a great improvement. 860 MW of installed capacity in 1992 has exceeded 2500 MW at the end of 1995. Major wind power companies that produce greater turbines and cost-effective models are Europe- based. Among the developing countries that have a great potential, India has led the way for the implementation of a commercial market for wind power.Though technology is mature, economical obstacles in front of the wind power utility are market stimulation for conventional technologies, financing of capital costs, site selection and some technological obstacles. Among reasons supporting the evolution and development process of wind power on the way leading to commercialization are financial facilities and high purchasing prices for renewable energy and resources especially in the European Union. But beyond these measures, the greatest force behind commercial use of wind power is the technological development process these systems faced during recent years; and the main factor providing this development is the R&D studies started by the oil shock of the seventies and concentrated on renewable resources as alternatives to fossil fuels. As wind turbines possess lighter and more aerodynamic blades, better aerodynamic and electronic control systems, and as they're produced in masses, costs have dramatically reduced; and this trend still haven't come to an end. Efficient energy extraction from the wind is dependent on meteorological characteristics of the region selected and more significantly on the turbine capacity and design. Research for a suitable site should consider wind characteristics and continuity for the commercial sustainability of the region. Aerodynamic and structural design aims more performance for less wind velocity. Though wind turbines are classified according to their rotation axis as horizontal axis and vertical axis wind turbines, both use similar aerodynamic principles. They use lifting force or dragging force for rotation. A, great majority of turbines used or produced today are horizontal axis wind turbines driyen by lifting forces. Rotor blades have airfoil sections similar to those of airplanes and design phase resembles to those of propellers; in fact they're modified from those methods. Research on development of wind energy systems are concentrated on the improvement of aerodynamic and mechanical performances of turbines, improvement of their strength-to-weight ratio and fatigue life, modeling and simulation of wind fields and development of offshore turbines. Large scale` offshore turbines offer great promise both for land use and planning problems and social acceptance, and capacity increase because of undisturbed wind field. By means of aer-odynamic research, technological improvement and a full understanding opportunity for the flow around a turbine exists. The subjects related with aerodynamic research today consists of : 1. Rotor Configuration, Blade Properties, Number of Blades 2. Aerodynamic Control 3. Profile Characteristics, Selection Criteria, Design and Impacts on Stall. 4. Blade element momentum method and potential flow methods for Performance Analysis. XI5. Dynamic Loads Analysis 6. Unsteady Aerodynamics, Dynamic Stall Experiments and models, Wake Effects 7. Turbulence Impacts on Rotor Blades Horizontal axis wind turbines are also evaluated according to their rotor configurations like wind orientation (direction of the air flow from front or behind the tower), blade properties (rigid or teetering), number of blades (two or three). Turbines most widely used for electricity generation currently are two or three- bladed, receiving the wind from in front of the tower. Recent research heavily emphasize the development of large two bladed turbines with rated powers more than 1MW. Aerodynamic control is used for limiting and optimizing power output. Methods to provide this is the utilization of constant, passive stall control or active pitch control. A recent system that has begun to be used in turbines commercially is variable speed rotors that tops the efficiency while reducing the dynamic loads. Stall delay met by the rotating machinery is a problem. Experiments state that there is a spanwise velocity distribution due to three dimensional flow separation. For this reason, special profile designs were needed to avoid generator damage by excessive rotation that was considered not to occur because of stall, likely to happen in forward flight. Special designs of profile families have used two major methods: aerodynamic shape optimization or potential flow methods-boundary layer analysis couplings. Performance prediction and analysis aims at the availability of aerodynamic loads and mean power output. It's a prior and critical position. The simplest and most widely used approach for performance is blade element/momentum method. Blade element/momentum method is based on the principle that the rotor can be considered as the spanwise sum of thin strips, called blade elements. Thus, loads on the blade can be obtained by the integration of the characteristics of these elements. Usually experimental profile characteristics are used for this purpose. Potential flow methods are used for a better analysis as BEM method is unable to take wake effects and stall conditions into account. In contrary, they require more of computation hardware and time. Toughest issue in front of the wind turbine model users is the determination of dynamic loads that play the major role on fatigue life of a rotor. Stochastic character of the wind and the flexible structure öf turbine causes an increasing nurnjber of parameters for the calculation of flow. Dynamic stall and dynamic inflow are fhg two majc* investigation areas for wind turbine flow characteristics. Potential xumethods offer an even greater promise for the understanding of the mechanisms of such flow conditions. A series of models were developed in order to simulate the stochastic loads on the rotor. Best models to simulate the wind are almost the most difficult ones to be solved, though fast computation methods were developed recently. All currently used methods use the longitudinal component of atmospheric turbulence. Some of the rotor reactions were, in contrast, reported to be sensitive against horizontal and vertical components of turbulence. Though blade element/momentum method provides an ease of understanding and computing, it's known that it is not accurate for some flow conditions like yawed flow, unsteady aerodynamics or stall conditions. They are also unable to consider wake effects on the turbine performance. For the detailed analysis of effects of these complex flow conditions on performance and three-dimensional flow field, analytical methods are sought. Vortex methods widely used by helicopter and propeller designers are suitable to be adapted for wind turbine rotors. Main obstacle for the use of these methods is the computation burden. However the progress taken by computer systems recently has led the optimism about the faster solution in the near future. The problem of potential flow is solved by the representation of rotor blades and vortex sheet by singularity elements like source, doublet and vortice elements; determination of the distribution of these singularities according to the boundary conditions and finally solution of the velocity field. Methods used for solution are lifting line, lifting surface and panel methods as well as others like free wake methods and asymptotic acceleration method. The main equation for the flow field is known as Laplace equation for flow perturbation potential and this equation is solved for the boundary condition of zero normal velocity over the surface of the body. Another aerodynamic condition is Kutta condition; wake shouldn't include any force, or, in another saying, there shouldn't be any pressure difference between lower and upper sides of the vortex sheet representing the wake. Wake shape for wind turbines is helical, so wake shape should be prescribed or, by means of iteration, a free wake method can be used. An expanding wake is reported not to affect the performance significantly, comparing with a cylindrical one. Lifting line method was first developed and modified for propellers by Prandtl. It reduces the lifting wing to a bound vortex and discretization is made by horseshoe vortexes which can at the same time represent the wake. Lifting surface method does not take the thickness into account but the chord. Singularities effect on the camber line. Discretization is made by doublet or equivalent vortex elements. The xmrepresentation of leading edge in lifting surface method causes a singularity. By the solution of Laplace equation under the boundary conditions, both methods lead to the determination of singularity distribution, velocity and pressure distributions and thus blade loads and performance coefficients. In panel method, aerodynamic surface is discreticized by a number of quadrilateral elements chordwise and spanwise. Constant, but initially unknown singularity distributions are placed on each panel. Main purpose of the method is the determination of the strengths of these singularities. Hence, velocity, pressure and loads distribution can be found resulting in a total power and thrust coefficient for the rotor. The leading edge singularity problem no longer exists in panel methods. These methods can be extended for the use of yawed flows and they can be coupled with three dimensional boundary layer analysis in order to take into account the viscosity and three dimensional flow separation effects. Wake shape can be either assumed beforehand or a relaxation method can be used. The prescription of an expanding wake is reported to be in good agreement with experiments, but not leading to sifnificant changes relative to a non-expanding one. An integral analysis of flow field around the turbine is possible by panel methods translated into computer codes. In this approach, codes generated for use in aircraft and ship propellers can be adapted for use in wind turbines. The choice of method depends on the balance between accuracy of the method and computation cost and time. Panel methods are expected to be more widely used by further improvements in computing facilities. A new method is asymptotic acceleration potential method developed in Delft Technology University. Accelerations in the flow field are represented by modal pressure differences on the blade. Integration of the acceleration of air particles lead to the velocities in rotor plane; thus aerodynamic loads can be determined. Though it's reported to have a significantly less computation time, the method is not used for different flow conditions yet. Aerodynamic research of any kind will contribute into the integrated design schemes developed recently. Development of these programs in which aerodynamic, structural and financial constraints are integrated will result in reduced risks and costs for new wind energy conversion systems. The constraint for the use is the financial one; optimum program should be selected according to the hardware and computation time it requires for execution. xiv ÖZET Günümüzde dünya çapında kullanımı en hızlı artan enerji kaynağı ve teknolojisi rüzgar enerjisi dönüşüm sistemleridir. Rüzgar gücü, çoğunlukla, yenilenebilir bir kaynak olması ve çevreye verdiği zararın diğer teknolojilere göre çok düşük olması nedeniyle gündeme gelmiştir. Ancak, rüzgar enerjisinden elektrik elde edilmesinin yaygınlaşmaya başlamasının başlıca nedeni, dönüşüm sistemlerinin ve elektrik enerjisi üretim maliyetlerinin yeni fosil-yakıtlı güç santralleriyle rekabet edebilecek düzeye inmiş olmasıdır. Bunu sağlayan etken de, özellikle 1970'lerdeki petrol şoku sırasında yeni ve yenilenebilir enerji kaynak ve teknolojileri üzerinde başlatılıp yoğunlaştırılan araştırma-geliştirme çalışmaları olmuştur. Rüzgar enerji sistemlerinin geliştirilmesi üzerindeki araştırmalar türbin sistemlerinin aerodinamik ve mekanik performanslarının artırılması, dayanıklılıklarının ve yorulma ömürlerinin geliştirilmesi, rüzgar alanlarının modellenmesi ve simule edilmesi ve açık denizde kurulması düşünülen türbinler üzerinde yoğunlaşmıştır. Aerodinamik araştırmalar ise, kesit profillerinin karakteristiklerinin performans üzerindeki etkileri, dinamik akım ayrılması ve taşıma kaybı mekanizmaları, iz bölgesi araştırmaları ve potansiyel akım metodlarıyla türbin çevresindeki akım özelliklerinin ve performans etkilerinin hesaplanması üzerine yapılmaktadır. Performans analizi, pal ve rotor üzerine etkiyen aerodinamik yüklerin ve ortalama güç çıktısının belirlenmesini amaçlamaktadır. Rotor tasarımında en öncelikli ve kritik aşamalardan biridir. Basit pal elemanı/momentum yöntemi anlama ve hesaplama kolaylığı sağlamasına karşın, eksenden sapmış (yanal) akım ve değişken aerodinamik etkiler gibi bazı koşullarda bu yöntemin yeterli geçerlilik sağlamadığı bilinmektedir. Bu yüzden kullanılması önerilen potansiyel akım yöntemleri, bilgisayar sistemlerinin gelişmesiyle bütüncül analiz olanakları sunmaktadırlar. Klasik potansiyel akım yöntemleri olan taşıma çizgisi, taşıma yüzeyi ve üç boyutlu panel yöntemleri uygun sonuçlar verebilmektedir. Aerodinamik araştırmaların asıl yaran, rüzgar türbinlerinin tasarımlarında bütüncül yaklaşımlara elde edilen bilgilerin eklenmesiyle görülecektir. Bu tasarım programlarının geliştirilmesi, yeni ürünlerin içerdiği risklerin ve maliyetlerin azalmasıyla sonuçlanacaktır. ix 58

Abstract Urban transformation is vital to global sustainable development as humans increasingly come to dwell in cities. Within cities, the mobility sector promises the highest potential of carbon emission reduction. The disruptive business innovation brought about by the advent of app-based smart-sharing systems is emancipating collaborative consumption of mobility at larger and deeper scales, ranging from car-pooling, expanded electric vehicle (EV) use to bike-sharing. Synchronizing the existing yet under-realized low-carbon transport modes in cities, such as public transport, with emerging and diversifying app-based sharing mobility business models, offers huge potential to transform urban mobility toward sustainability. Yet, the rapid business expansion and innovation of the sharing mobility companies have profoundly challenged existing socio-economic relationships, knowledge systems and physical infrastructures in cities. This study explores the synergy between the social-ecological innovation in the sharing economy and the sustainable development of urban systems, using empirical data from three business cases in the emerging sharing mobility sector – in modes of ride-sharing, EV-sharing and bike-sharing - of Shanghai, China. It indicates that there is a strong co-evolution mechanism between the transformation towards more sustainable city at the macro-level and the business ecosystem innovation towards greener and smarter transport at the meso-level. We argue that the two level transformations, triggered by the disruptive innovation of the sharing economy and led by urban transformation towards sustainability, mutually influence each other and re-enforce sustainable values and practices in the fast changing urban context and business innovations in Shanghai.

This study evaluates and compares the economic performance of four (agro-) forestry plantations on alkaline soils in semi-arid conditions in the North Indian state of Haryana. The plantations were located in the villages of Gudha, Kohand, Nain and Sutana. The plantations varied with respect to the plantation management, the tree species and the use of intercrops. The economic performance is evaluated by calculating the net present values (NPVs) of the four (agro-) forestry systems. The NPVs are compared to the NPVs of the reference land use, i.e., the land use before the establishment of the (agro-) forestry plantations. The impact of soil regeneration via (agro-) forestry plantations on the NPVs is evaluated as well. Also the costs of production (COP) of three biomass applications (fuelwood, timber and charcoal) are calculated and compared to market prices to estimate the economic competitiveness of these commodities. The results show that the NPV ranges from −196 to 1197 €/ha without subsidies and 318 to 1441 €/ha with subsidies. In most cases the NPVs of subsidized plantations are well above the NPVs of the reference land use. However, without subsidies only the NPV of the (agro-) forestry plantation in Gudha is higher than that of the reference land use. The highest NPV is observed in Gudha, which is due to the high economic value of the tree species Acacia nilotica and Eucalyptus teriticornis and the fodder crop Leptochloa fusca. In Nain and Sutana Prosopis juliflora trees were planted at a higher density compared to Gudha and Kohand, which resulted in a higher productivity, but also higher establishment and maintenance costs. The net result is a NPV lower than at Gudha. Furthermore, the study found that (agro-) forestry plantations can help regenerate alkaline soils for conventional rice and wheat production. Soil regeneration can increase the NPV strongly but the actual increase depends on the method used to quantify the value of soil regeneration. The results also indicate that the production of fuelwood and charcoal from wood from (agro-) forestry plantations on alkaline soils is competitive with existing production chains. For timber the results are mixed. The results of this study show the need and benefits of optimizing the economic performance of (agro-) forestry plantations as part of current and future policies by, for example, subsidizing (parts of the) establishment costs and creating a mechanism by which soil regeneration is rewarded.