Suchergebnisse

Currently, benefits generated by natural environments, such as carbon sequestration or water retention and others, are measured in economic terms based on "willingness to pay" of society (using the TEV or Total Economic Valuation). Thanks to these measurements, decisions can be made about items related to natural ecosystems in the field of politics, construction projects and quantification of financial aids for the agricultural sector. However, a group of scientists involved in Environmental Economy, thinks that this method is not suitable, as society do not really know the true value of the functions of the ecosystems. Even more, they add that solution has to do with the energy measurement of those benefits in order to give them their real value (objective value). In contrast, another group of scientists consider that Ecosystem Services (ES) valuation based on society's opinion is completely necessary, justifying that these values are lated used as a politic tool. Therefore, the Thesis borns on order to answer this controversy, beginning with the energy calculations of the benefits produced by agricultural environments dedicated to energy crops. Besides, it also aims to clear if the current subjective method of valuation, the TEV, is the best choice for the job of political tool or if there is instead, another better way of doing this. To do that, It has been used an innovative method; The Emergy Method (spelled with "m"). This method consist of determining the necessary energy investment for developing services such as carbon sequestration or water retention, among others. In other words, it allows to obtain the environmental effort printed on the implementation of beneficial ecological functions for human being. With results already obtained, it can be seen; first, the energy investment necessary for biomass production; second, the current method, based on Total Economic Valuation does not express the true value of the ecosystem functions as are undervalued in 331 dollars per hectare and year (in energy crops); third, the best way for valuing ES implies a combination of methods, the Emergy and the TEV. Finally, through the obtention of the energy investment required by the environment for the biomass production, first steps for developing an application that allows to define the most proper areas for a biomass burner industry are given. These areas bounds the surface in which the obtention of a joule of electricity using energy crops requires less environmental effort that the same joule based on fossil fuels, taking on account the terrain, the geometry of the roads used for supplying the industry of biomass and the efficiency of the combustion process. ; Ingeniería Agronómica ; Nekazaritza Ingeniaritza

The European renewable energy directive 2009/28/EC (E.C. 2009) provides a legislative framework for reducing GHG emissions by 20%, while achieving a 20% share of energy from renewable sources by 2020. Perennial energy crops could significantly contribute to limit GHG emissions through replacing equivalent fossil fuels and by sequestering a considerable amount of carbon into the soil through the large amounts of belowground biomass produced. The objective of this study is to evaluate the effects of land use change that perennial energy crops have on croplands (switchgrass) and marginal grasslands (miscanthus). For that purpose above and belowground biomass, SOC variation and Net Ecosystem Exchange were evaluated after five years of growth. At aboveground level both crops produced high biomass under cropland conditions as well as under marginal soils. At belowground level they also produced large amounts of biomass, but no significant influences on SOC in the upper layer (0-30 cm) were found. This is probably because of the "priming effect" that caused fast carbon substitution. In switchgrass only it was found a significant SOC increase in deeper layers (30-60 cm), while in the whole soil profile (0-60 cm) SOC increased from 42 to 51 ha-1. However, the short experimental periods (for both switchgrass and miscanthus), in which land use change was evaluated, do not permit to determine the real capacity of perennial energy crops to accumulate SOC. In conclusion the large amounts of belowground biomass enhanced the SOC dynamic through the priming effect resulting in increased SOC in cropland but not in marginal grassland.

In the EU, 20% of primary energy demand is to be covered by renewable energy sources by 2020 in order to reduce emissions of climate-relevant gases and dependence on imports of fossil energy sources. Biomass is the most important renewable energy source in both the European Union and Germany, with a share of around two thirds. Bioenergy sources play a major role in the expansion strategies for renewable energies. Biofuel and biogas production have risen sharply in Germany in recent years due to government subsidies. This part of bioenergy is essentially based on energy crop cultivation (mainly rapeseed and maize). However, with food prices rising sharply worldwide, especially in 2007/2008, the expansion targets for biofuels have been called into question to some extent. There was controversy about the extent to which the increasing production of biofuels had contributed to this price increase. With the financial and economic crisis, agricultural prices then fell significantly, and agriculture is in the midst of a revenue and income crisis in which energy crops can once again gain importance as an income option. Another point of discussion is the extent to which ambitious expansion targets will lead to the import of bioenergy sources and thus trigger an expansion of cultivated areas in tropical exporting countries at the expense of rainforest. In the case of large-scale rainforest clearing, this would even mean increased greenhouse gas emissions instead of their reduction. These rapid changes in the public debate pose particular challenges for scientific policy advice in this topic area. Subject and aim of the study The TA project "Opportunities and challenges of new energy crops" (short title "Energy Crops") was approved by the Committee on Education, Research and Technology Assessment on 27 September 2006. Due to the importance of the very complex topic and the manifold demands on the project, a staged approach was chosen. In the first phase of the project, the focus was on the review and comparative evaluation ...

The climatic, energetic and political context promotes the development of bioenergies. However we have a lack of knowledge to find out the best energy crops, depending on the soil, the climate and the end-use. This work aimed at studying the adaptation and the biomass and biofuel yield, of several energy crops grown in France in different soil and climate conditions. The biomass yields were very variable between the different experimental sites and no differences were observed on the median biomass yield between crops. Moreover, there was no evidence of a highly productive crop in all the conditions of soil and climate. Because of little differences of the lower heating value between crops, no differences were observed on the primary energy yield. The ethanol yield per hectare was higher for miscanthus, switchgrass and fiber sorghum because of higher cellulose content in these crops. The nitrogen removed at harvest by miscanthus and switchgrass were significantly lower than the other crops witch could lead to reduced fertilizer-N requirements. Further research are needed to clarify the effect of limiting factors on the biomass yield of the different energy crops and to consider other parameters such as the environmental impacts to give rules to choose the most suitable crop in a given region.

Both proponents and opponents of the use of transgenic seeds in developing countries assume that genetic engineering can have far-reaching effects under the ecological, economic, social and institutional conditions of both less developed and emerging countries. On the one hand, there are great expectations that genetic engineering will contribute to food security and economic integration with the industrialised countries; on the other hand, there are great fears about adverse effects on small-scale farming and the traditional use of seeds. The "mega issue" of bioenergy, which in recent years has intensified and intensified the global debate on goals, ways and priorities for the future use of natural resources as a whole, has also triggered the question of the potential of green genetic engineering with new dynamism. From the perspective of its proponents, genetic engineering is seen both as an indispensable means of increasing yields per unit area in arable farming as a whole and for the specific optimisation of "energy crops". Critics of agrogenetic engineering, on the other hand, doubt these assessments and fear a potentiation of the negative ecological, health and above all socio-economic consequences they assume. Subject matter and aim of the study The aim of the TAB project "Effects of the use of transgenic seeds on economic, social and political structures in developing countries", which was initiated by the Committee for Economic Cooperation, was to review the general information and debate on this issue and to record as concretely as possible how the use of transgenic seeds has actually developed in the past twelve years, what consequences can be identified and what can be derived from this for the future design of German (and also European) development policy. The report focuses on four case studies on countries with extensive (Brazil, China) and limited (Chile, Costa Rica) use of genetically modified plants (GM plants). The results of these country studies were discussed comparatively with regard to ...

National audience ; The climatic, energetic and political context promotes the development of bioenergies. However we have a lack of knowledge to find out the best energy crops, depending on the soil, the climate and the end-use. This work aimed at studying the adaptation and the biomass and biofuel yield, of several energy crops grown in France in different soil and climate conditions. The biomass yields were very variable between the different experimental sites and no differences were observed on the median biomass yield between crops. Moreover, there was no evidence of a highly productive crop in all the conditions of soil and climate. Because of little differences of the lower heating value between crops, no differences were observed on the primary energy yield. The ethanol yield per hectare was higher for miscanthus, switchgrass and fiber sorghum because of higher cellulose content in these crops. The nitrogen removed at harvest by miscanthus and switchgrass were significantly lower than the other crops witch could lead to reduced fertilizer-N requirements. Further research are needed to clarify the effect of limiting factors on the biomass yield of the different energy crops and to consider other parameters such as the environmental impacts to give rules to choose the most suitable crop in a given region.

National audience ; The climatic, energetic and political context promotes the development of bioenergies. However we have a lack of knowledge to find out the best energy crops, depending on the soil, the climate and the end-use. This work aimed at studying the adaptation and the biomass and biofuel yield, of several energy crops grown in France in different soil and climate conditions. The biomass yields were very variable between the different experimental sites and no differences were observed on the median biomass yield between crops. Moreover, there was no evidence of a highly productive crop in all the conditions of soil and climate. Because of little differences of the lower heating value between crops, no differences were observed on the primary energy yield. The ethanol yield per hectare was higher for miscanthus, switchgrass and fiber sorghum because of higher cellulose content in these crops. The nitrogen removed at harvest by miscanthus and switchgrass were significantly lower than the other crops witch could lead to reduced fertilizer-N requirements. Further research are needed to clarify the effect of limiting factors on the biomass yield of the different energy crops and to consider other parameters such as the environmental impacts to give rules to choose the most suitable crop in a given region.

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa Para a obtenção do Grau de Mestre em Energia e Bioenergia ; Energy crops offer ecological advantages over fossil fuels by contributing to the reduction of greenhouse gases and acidifying emissions. However, there could be ecological shortcomings related to the intensity of agricultural production. There is a risk of polluting water and air, losing soil quality, enhancing erosion and reducing biodiversity. In the scope of the project Future Crops for Food, Feed, Fiber and Fuel (4F Crops), supported by the European Union, an environmental impact assessment study was developed and applied to the cultivation of potential energy crops in the Mediterranean Europe. The categories selected were: use of water and mineral resources, soil quality and erosion, emission of minerals and pesticides to soil and water, waste generation and utilization, landscape and biodiversity. Results suggest that annual cropping systems have a more negative impact on the environment than lignocellulosic and woody species, namely regarding erodibility and biodiversity. Annual systems and woody crops are also more damaging to soil quality than herbaceous perennials. However, differences among crop types are not as evident in the remaining indicators. Impact reduction strategies are limited to crop management options, but, site specific factors should be accurately assessed to evaluate the adequacy between crop and location. ; This work was supported by the European Union (Project 4F Crops – Future Crops for Food, Feed, Fiber and Fuel, Grant Agreement No: 212811, Coordination and Support Actions, FP7-KBBE-2007-1)

Unter anaerober Vergärung versteht man die Umsetzung von organischem Material zu anorganischem Material und methanhältigem Gas unter Ausschluss von Sauerstoff. Die Anaerobtechnik wird heute zumeist im Bereich der Abwassertechnik eingesetzt, doch gewinnen Biogasanlagen zur Energiegewinnung immer mehr an Bedeutung. Verschiedenste Probleme verringern jedoch die Effizienz dieser Anlagen, wie niedrige Methankonzentration im Gas, Selbsterwärmung oder Geruchsprobleme. Daher ist eine Optimierung des Prozesses notwendig. Ziel dieser Arbeit ist die Optimierung des Prozesses durch Modellierung und Steuerung der anaeroben Vergärung von Energiepflanzen. Basis jeder guten Steuerung ist nicht nur ein ausgereiftes Messsystem, sondern auch ein umfangreiches Wissen über den Prozess selbst. Um einen guten Einblick in den Biogasprozess zu bekommen, sind Modelle ein gutes Hilfsmittel. In dieser Arbeit wurde das Anaerobic Digestion Model No.1 (ADM1) herangezogen. Das ADM1 ist ein mathematisches Modell das den Biogasprozess beschreibt. Da das Modell sehr allgemein ist, wurde es für die Modellierung der anaeroben Vergärung von Energiepflanzen leicht adaptiert. Aufgrund der Komplexität des Modells befasst sich ein großer Teil der Arbeit mit der Kalibrierung des Models. Dabei wurde unter anderem eine Methode entwickelt mit denen die Anfangsbedingungen ohne aufwendige Messungen abgeschätzt werden können. Das modifizierte Model wurde schließlich in das sogenannte Virtual Laboratory (VL) implementiert ein Softwaretrainingstool, dass den Benutzer Einblick in den Biogasprozess geben soll. Weiters wurde ein Decision Support Tool (DSS) - auf Fuzzy Logik basierend weiterentwickelt. Um verschiedene Tools miteinander vergleichen zu können, wurde eine auf Composite Programing und dem ADM1 basierende Methode verwendet. ; Anaerobic digestion (AD) of wastewater, organic wastes and biomass results in the formation of biogas, which can be processed to electrical energy and heat. Thanks to special government subsidies, there has been a veritable boom in biogas-plant technology in Austria in recent times. In order to integrate the production of energy from biogas into the existing energy infrastructure, the AD of biomass has to be optimized. Not only to make the process economically attractive, but also to solve certain problems e.g. low methane values in the biogas (approximately 50%), self-heating in the plants and the odors from fermentation. Objective of this study is the optimization of the process by improved process control. In this case, the advanced control is achieved using a Decision Support System (DSS) based on Fuzzy Logic. Yet the implementation of an effective control tool, apart from the advanced monitoring of the plant, requires a good knowledge of the AD process itself. This knowledge of the biogas process can be obtained using process models. In this study the Anaerobic Digestion Model No.1 was used. The ADM1 is a mathematical model describing the biogas process and was developed by the IWA Task group for Mathematical Modeling of Anaerobic Digestion Processes. As the ADM1 is not fully suitable for modeling the anaerobic digestion of energy crops, the model had to be slightly adapted. A large part of the study deals with the calibration of the model, due to its complexity. The adapted version of the model was then used as the basis for the so-called "Virtual Laboratory" (VL) a software training tool, which provides users with the possibility of gaining more insight into the biogas process. ; eingereicht von Alexandra Wolfsberger ; Abweichender Titel laut Übersetzung der Verfasserin/des Verfassers ; Zsfassung in dt. Sprache ; Wien, Univ. für Bodenkultur, Diss., 2008 ; OeBB ; (VLID)1931451

The development of viable lignocellulosic-biofuel industries in the United States will require dependable delivery of supplies of feedstocks. The selection of feedstocks ultimately will vary with geographical region across the United States. Dedicated bioenergy crops as sources of lignocellulose are likely to be most productive in the southern regions of the United States due to more abundant sunlight and longer growing seasons. Of course, dedicated bioenergy crops in the southwest must tolerate heat and drought, whereas species grown along the Gulf Coast must tolerate heat as well as variable soil moisture and variable soil-oxygen environments associated with different soil types. Dedicated energy crops for the panhandle of Texas and the Midwest will have shorter growing seasons and will need to be more cold tolerant.

The first essay formulates a dynamic general equilibrium optimal control model of an energy crop as part of a country's planned resource use over a period of time. The model attempts to allocate consumption, production, and factors of production to achieve the country's sustainable development goal. A Cobb-Douglas specification is used for both utility and production functions in the model. We calibrate the model with Thailand data. The selected model is used to generate the stationary state solution and to simulate the optimal policy function and optimal time paths. Two methods are used: a linear approximation method and the Runke-Kutta reverse shooting method. The model provides numerical results that can be used as information for decision makers and stakeholders to devise an economic plan to achieve sustainable development goals. The second essay studies the effect of international trade and changes in labor supply, land supply, and the price of imported energy on energy crop production for bio fuel and food, as well as impacts on social welfare. We develop a dynamic general equilibrium model to describe two baseline scenarios, a closed economy and an open economy. We find that international trade increases welfare and decreases the energy price. Furthermore, resources are allocated to produce more food under the open economy scenario than the quantities produced under a closed economy assumption. An increase in labor supply and land supply result in an increase in social welfare. An increase in imported energy price leads to a welfare loss, higher energy production, and lower food production. The third essay develops a partial equilibrium econometric model to project the impacts of an increase in ethanol production on the Thai agriculture sector over the next ten years. The model is applied to three scenarios for analyzing the effect of government ethanol production targets. The results from the baseline model and scenario analysis indicate that an expansion in ethanol production will result in a significant increase in cassava production, price, and land use. The increase in cassava production will shift land use from maize and sugar cane, thus increasing in price of maize.

Energy crops are cultivated primarily for bioenergy production, but can also have wider benefits to agriculture and the environment. Policies put in place in the UK and Europe have promoted bioenergy and the growth of energy crops. Despite the various policy support mechanisms the cultivation of perennial energy crops has proceeded at a low rate. This study rigorously analyses some of the key UK bioenergy policies since 1990 to assess why perennial energy crops have not fulfilled their potential. The UK energy crops market is scrutinised and shows the industry is still nascent compared to Government aspirations. Case studies of both successful and unsuccessful projects are evaluated to reveal how effective different policies have been in establishing UK perennial energy crops. This original review shows significantly that none of the projects, initiatives or schemes described can be viewed as an absolute success. The main obstacles that have hindered progress include: the lack of long term supportive energy crops policy, the failure of headline projects and organisations, the lack of competitiveness of long term perennial crop options compared to annual crops, bureaucracy of schemes, over-ambitious projects, and large-scale support schemes tending to favour imported biomass rather than support domestic supply. 25 years of failed energy crops policy suggests there needs to be a long term strategy. Future support for the sector must join up policy between different Government departments to recognise multi-functional benefits of perennial energy crops. Support mechanisms could aim to provide a competitive advantage for local supply and use, and improve management of cashflows during establishment. The risk burden should be shared between suppliers and end-users. Smaller-scale projects using established technologies are required with energy crops introduced in a phased manner. Supply-side measures need to be balanced with demand-side incentives to link supply with end-user markets.