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Direct Use (direct + use)
Selected AbstractsInvestigation into Direct Use of Protected 3,4-Dehydropyroglutamates in Synthesis.CHEMINFORM, Issue 49 2005Claire M. Moody Abstract For Abstract see ChemInform Abstract in Full Text. [source] Direct use of vegetable oil and animal fat as alternative fuel in internal combustion engineBIOFUELS, BIOPRODUCTS AND BIOREFINING, Issue 2 2008Pinaki Mondal Abstract Gradual depletion of world petroleum reserves and the impact of environmental pollution of increasing exhaust emissions lead to the search for a suitable alternative fuels for diesel engines. The substitution of conventional fuels (gasoline, diesel) by renewable biofuels is considered a potential way to reduce pollution and to support the sustainable development of a country. Direct use of vegetable oil and animal fat is a promising alternative to solve these problems. An exhaustive review of the experiments in this area, carried out by several researchers in last three decades, is presented here. Different problems associated with the direct use of vegetable oil and animal fat and potential solutions from both public and private sectors are discussed. Some engine manufacturers have started to launch full-warranty engines with vegetable oil as fuel. It is expected that the competitive engine market will witness more intense research, resulting in the launch of more vegetable-oil engines with full warranties. The steep rise in food prices in recent years is concerning policy-makers and has raised the old ,food vs fuel' debate. It has been concluded that vegetable oil can probably only substitute small to medium portions of petroleum-based fuel due to future severe land-usage competition from food sector. This calls for intense research initiatives into the production of suitable fuel from non-edible vegetable oil, grown in wasteland. In this regard, genetic engineering may prove to be extremely effective in developing ,designer fuel'. © 2008 Society of Chemical Industry and John Wiley & Sons, Ltd [source] Evaluation of Thin Film Titanium Nitride Electrodes for Electroanalytical ApplicationsELECTROANALYSIS, Issue 10 2007Carolina Nunes, Kirchner Abstract Titanium nitride is a hard and inert conducting material that has yet not been widely used as electrode material for electroanalytical applications although there are highly developed protocols available to produce well adherent micro and nanostructured electrodes. In this paper the possibilities of using titanium nitride thin films for electroanalytical applications is investigated. Scanning electrochemical microscope (SECM) was used for analysis of the redox kinetics of a selected fast redox couple at thin films of titanium nitride (TiN) in different thicknesses. The investigation was carried out by approaching an amperometric ultramicroelectrode (UME) to the TiN film while the soluble redox couple (ferrocenemethanol/ferrociniummethanol) served as mediator in a SECM configuration. The substrate was biased at a potential so that it rereduces the species being produced at the UME, thus controlling the feedback effect. Normalized current,distance curves were fitted to the theoretical model in order to find the apparent heterogeneous standard rate constant (k°) at the sample. The data are further supported by structural investigation of the TiN films using scanning force microscopy and X-ray photoelectron spectroscopy. It was found that the kinetics are little influenced by prolonged storage in air. The heterogeneous standard rate constants in 2,mM ferrocenemethanol were (0.73±0.05)×10,3,cm s,1 for 20,nm TiN thin layer, (1.5±0.2)×10,3,cm s,1 for 100,nm TiN thin layer and (1.3±0.2)×10,3,cm s,1 for 300,nm TiN thin layer after prolonged storage in air. Oxidative surface treatment (in order to remove organic adsorbates) decreased the kinetics in agreement with a thicker oxide layer on the material. The results suggest that their direct use for amperometric detection of reversible redox systems in particular at miniaturized configurations may be advantageous. [source] A Reference Electrode for Electrochemical and Cryoelectrochemical Use in Tetrahydrofuran SolventELECTROANALYSIS, Issue 21 2005Christopher Abstract We report a reference electrode for direct use in tetrahydrofuran (THF) at low temperatures. A reference solution containing equimolar amounts of ferrocene/ferrocenium hexafluorophosphate (Fc/Fc+) are prepared to give a 4,mM solution in THF that contains tetrabutylammonium hexafluorophosphate (TBAF) supporting electrolyte thus, minimizing liquid junction potentials. The reference solution is added to a sealed glass tube with a porous frit at one end, and a platinum wire is inserted into the tube. The reference electrode assembly is then inserted into a THF test solution. Potentiometric measurements show that the system responds in the expected Nernstian fashion over the concentration and temperature ranges, 4,mM to 40,,M and 20,°C to ,45,°C respectively. In addition, it is shown by steady,state cyclic voltammetry at a platinum microelectrode that the chemical reactivity of ferrocenium hexafluorophosphate (Fc+) otherwise seen in THF is suppressed by ion-pairing with PF using tetrabutylammonium hexafluorophosphate (TBAF) as the supporting electrolyte. [source] Optimization-based dynamic human walking prediction: One step formulationINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 6 2009Yujiang Xiang Abstract A new methodology is introduced in this work to simulate normal walking using a spatial digital human model. The proposed methodology is based on an optimization formulation that minimizes the dynamic effort of people during walking while considering associated physical and kinematical constraints. Normal walking is formulated as a symmetric and cyclic motion. Recursive Lagrangian dynamics with analytical gradients for all the constraints and objective function are incorporated in the optimization process. Dynamic balance of the model is enforced by direct use of the equations of motion. In addition, the ground reaction forces are calculated using a new algorithm that enforces overall equilibrium of the human skeletal model. External loads on the human body, such as backpacks, are also included in the formulation. Simulation results with the present methodology show good correlation with the experimental data obtained from human subjects and the existing literature. Copyright © 2009 John Wiley & Sons, Ltd. [source] Highly Linear-Selective Hydroformylation of 1-Alkenes using Formaldehyde as a Syngas SubstituteADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 2-3 2010Gouki Makado Abstract A highly linear-selective hydroformylation of 1-alkenes using formaldehyde without the direct use of syngas is described. One rhodium(I) complex catalyzes two processes in the overall hydroformylation of 1-alkenes using formaldehyde as the syngas substitute to give hydroformylated aldehydes with excellent regioselectivities. A high regioselectivity (linear/branched=up to 98/2) and chemical yield (up to 95%) can be achieved by the simultaneous use of two types of phosphanes as ligands. [source] Continuous Hydrogen Generation from Formic Acid: Highly Active and Stable Ruthenium CatalystsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2009Albert Boddien Abstract The ruthenium-catalyzed decomposition of formic acid was investigated with respect to continuous hydrogen generation and long-term stability of the catalytic systems. A highly active and stable system is presented, which was studied in batch and continuous modes for up to two months. The optimized catalyst system containing N,N -dimethyl- n -hexylamine with an in situ generated catalyst from (benzene)ruthenium dichloride dimer [RuCl2(benzene)]2 and 6 equivalents of 1,2-bis(diphenylphosphino)ethane (dppe) reached at room temperature a total turnover number (TON) of approximatly 260,000 with average turnover frequency (TOF) of about 900,h,1. Only hydrogen and carbon dioxide were detected in the produced gas mixture which makes this system applicable for direct use in fuel cells. [source] Ecotourism and biodiversity conservation in Jozani,Chwaka Bay National Park, ZanzibarAFRICAN JOURNAL OF ECOLOGY, Issue 2009Layla A. Salum Abstract This study is based on a study undertaken to assess how ecotourism has influenced biodiversity conservation in Jozani,Chwaka Bay National Park (JCBNP). It involved two communities surrounding the park, namely Pete and Kitogani. Field data were collected using structured questionnaires, key informant interviews and field observations. Questionnaires were administered to 76 households, whereas key informant interviews were conducted with foresters and JCBNP officials. Data analysis was undertaken using standard statistical methods. Findings from the study show that biodiversity management in the JCBNP has improved considerably after the introduction of ecotourism. The number of endemic colobus monkeys (Piliocolobus kirkii) and other rare species has increased. However, this achievement has been attained by restricting surrounding communities from using forest resources without providing alternative sources of livelihood. Findings also show that the benefits from ecotourism do not reach individual households, but the community as whole, in form of various social services. This has caused some resentment among the local people leading to their reluctance to reduce their direct use of ecosystem services available in the JCBNP, claiming that they cannot sustain their livelihood without such services. This has become a major source of conflict between the JCBNP and surrounding communities. Increased awareness and knowledge on biodiversity conservation would be needed for the communities surrounding the park to realize the potential and long-term benefits of ecotourism, and hence the need for their increased involvement in biodiversity management. [source] MOISTURE SORPTION CHARACTERISTICS of STARCH GELS.JOURNAL OF FOOD PROCESS ENGINEERING, Issue 3 2004PART II: THERMODYNAMIC PROPERTIES ABSTRACT A thermodynamic approach was used to interpret the experimental adsorption and desorption isotherm data for potato starch gel. Calculation of the thermodynamic properties (differential enthalpy, integral enthalpy, differential entropy and integral entropy) provides an understanding of the properties of water and energy requirements associated with the sorption behavior. Isosteric heats (differential enthalpies) were calculated through direct use of moisture isotherms by applying the Clausius-Clapeyron equation. the differential enthalpy and entropy decreased with increasing moisture content and were adequately characterized by an exponential model. A plot of differential heat versus entropy satisfied the enthalpy-entropy compensation theory. the spreading pressure increased with increasing water activity, and decreased with increasing temperature. the net integral enthalpy increased with moisture content to a maximum value (around the monolayer moisture content) and then decreased. In a reverse manner, the net integral entropy decreased with moisture content to a minimum value and then increased. [source] An analysis of uncertainty in non-equilibrium and equilibrium geothermobarometryJOURNAL OF METAMORPHIC GEOLOGY, Issue 9 2004J. R. ASHWORTH Abstract In statistically optimised P,T estimation, the contributions to overall uncertainty from different sources are represented by ellipses. One source, for a diffusion-controlled reaction at non-equilibrium, is diffusion modelling of the reaction texture. This modelling is used to estimate ratios, Q, between free-energy differences, ,G, of reactions among mineral end-members, to replace the equilibrium condition ,G = 0. The associated uncertainty is compared with those already inherent in the equilibrium case (from end-member data, activity models and mineral compositions). A compact matrix formulation is introduced for activity coefficients, and their partial derivatives governing error propagation. The non-equilibrium example studied is a corona reaction with the assemblage Grt,Opx,Cpx,Pl,Qtz. Two garnet compositions are used, from opposite sides of the corona. In one of them, affected by post-reaction Fe, Mg exchange with pyroxene, the problem of reconstructing the original composition is overcome by direct use of ratios between chemical-potential differences, given by the diffusion modelling. The number of geothermobarometers in the optimisation is limited by near-degeneracies. Their weightings are affected by strong correlations among Q ratios. Uncertainty from diffusion modelling is not large in comparison with other sources. Overall precision is limited mainly by uncertainties in activity models. Hypothetical equilibrium P,T are also estimated for both garnet compositions. By this approach, departure from equilibrium can be measured, with statistical uncertainties. For the example, the result for difference from equilibrium pressure is 1.2 ± 0.7 kbar. [source] Plant responses to drought and phosphorus deficiency: contribution of phytohormones in root-related processesJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 4 2005Lutz Wittenmayer Abstract Environmental stresses are one of the most limiting factors in agricultural productivity. A large portion of the annual crop yield is lost to pathogens (biotic stress) or the detrimental effects of abiotic-stress conditions. There are numerous reports about chemical characterization of quantitatively significant substrate fluxes in plant responses to stress factors in the root-rhizosphere system, e.g., nutrient mobilization, heavy-metal and aluminum immobilization, or establishment of plant-growth-promoting rhizobacteria (PGPR) by exudation of organic anions, phytosiderophores, or carbohydrates into the soil, respectively. The hormonal regulation of these responses is not well understood. This paper highlights this complex process, stressing the involvement of phytohormones in plant responses to drought and phosphorus deficiency as examples. Beside ethylene, abscisic acid (ABA) plays an important role in drought-stress adaptation of plants. This hormone causes morphological and chemical changes in plants, ensuring plant survival under water-limited conditions. For example, ABA induces stomata closure, reduction in leaf surface, and increase in root : shoot ratio and, thus, reduction in transpiration and increase in soil volume for water uptake. Furthermore, it supports water uptake in soil with decreasing water potential by osmotic adjustment. Suitability of hormonal parameters in the selection for improving stress resistance is discussed. Auxins, ethylene, and cytokinins are involved in morphological adaption processes to phosphorus (P) deficiency (increase in root surface, e.g., by the formation of more dense root hairs or cluster roots). Furthermore, indole-3-acetic acid increases root exudation for direct and indirect phosphorus mobilization in soil. Nevertheless, the direct use of the trait "hormone content" of a particular plant organ or tissue, for example the use of the drought-stress-induced ABA content of detached leaves in plant breeding for drought-stress-resistant crops, seems to be questionable, because this procedure does not consider the systemic principle of hormonal regulation in plants. Reaktionen von Pflanzen auf Trockenstress und Phosphormangel: Die Rolle von Phytohormonen in wurzelbezogenen Prozessen Umweltstress stellt den wesentlichsten Limitierungsfaktor für die landwirtschaftliche Produktion dar. Ein erheblicher Teil der jährlichen Ernten geht durch pathogene Organismen (biotischer Stress) oder durch die verheerende Wirkung abiotischer Stressoren verloren (v. a. Trockenstress und Nährstoffmangel). Es gibt zahlreiche Untersuchungen zur stofflichen Charakterisierung der pflanzlichen Stressreaktion an der Wurzel, z.,B. Nährstoffmobilisierung, Schadstoffimmobilisierung oder Etablierung von wachstumsfördernden Rhizobakterien durch Wurzelabscheidungen. Die hormonelle Steuerung dieser Prozesse ist bisher weniger erforscht. Der Artikel geht dieser Problematik am Beispiel von Trockenstress und Phosphormangel unter besonderer Berücksichtigung von Phytohormonen nach. Bei der Anpassung von Pflanzen an Wassermangelbedingungen spielt neben Ethylen das Phytohormon Abscisinsäure (ABA) eine wichtige Rolle. Es induziert morphologische und chemische Veränderungen in der Pflanze, die ein Überleben unter Wassermangelbedingungen ermöglichen. Beispielsweise induziert die ABA den Stomataschluss, eine Verringerung der Blattoberfläche sowie eine Erhöhung des Wurzel:Spross-Verhältnisses und bewirkt dadurch eine verringerte Transpiration und Vergrößerung des Bodenvolumens zur Erschließung von Wasservorräten. Darüber hinaus kann eine ABA-induzierte Anreicherung von osmotisch wirksamen Verbindungen zur Wasseraufnahme bei sinkendem Wasserpotential im Boden beitragen. Bei Phosphat (P)-Mangel sind vor allem Auxine, Cytokine und Ethylen an der morphologischen Anpassung der Wurzeln (Vergrößerung der Wurzeloberfläche durch verstärkte Bildung von Wurzelhaaren oder Proteoidwurzeln) beteiligt. Darüber hinaus bewirkt Indolyl-3-Essigäure eine Intensivierung der Abgabe von Wurzelabscheidungen zur direkten oder indirekten P-Mobilisierung in der Rhizosphäre. Trotzdem wird die unmittelbare Verwendung des Indikators "Hormongehalt" eines bestimmten Pflanzenorganes, beispielsweise der trockenstressinduzierte ABA-Gehalt von abgeschnittenen Blättern, für die Züchtung auf Stressresistenz als problematisch angesehen, da sie das systemische Prinzip der Hormonregulation nicht berücksichtigt. [source] Characteristics of tissue-centric biomedical researchers using a survey and cluster analysisJOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 8 2008Sujin Kim The objective of this study was to characterize the types of tissue-centric users based on tissue use, requirements, and their job or work-related variables at the University of Pittsburgh Medical Center (UPMC), Pittsburgh, PA. A self-reporting questionnaire was distributed to biomedical researchers at the UPMC. Descriptive and cluster analyses were performed to identify and characterize the complex types of tissue-based researchers. A total of 62 respondents completed the survey, and two clusters were identified based on all variables. Two distinct groups of tissue-centric users made direct use of tissue samples for their research as well as associated information, while a third group of indirect users required only the associated information. The study shows that tissue-centric users were composed of various types. These types were distinguished in terms of tissue use and data requirements, as well as by their work or research-related activities. [source] Necks-for-sex or competing browsers?JOURNAL OF ZOOLOGY, Issue 1 2010A critique of ideas on the evolution of giraffe Abstract Recent years have witnessed a resurgence in tests of the evolution and origin of the great height and long neck of the giraffe Giraffa camelopardalis. The two main hypotheses are (1) long necks evolved through competition with other browsers allowing giraffe to feed above them (,competing browsers' hypothesis); or (2) the necks evolved for direct use in intra-sexual combat to gain access to oestrous females (,necks-for-sex' hypothesis). Here, we review recent developments and their relative contribution in explaining giraffe evolution. Trends from Zimbabwean giraffes show positive allometry for male necks and isometry for female necks relative to body mass, while comparative analyses of the cervical versus the total vertebral column of the giraffe, okapi and fossil giraffe suggest selection specifically on neck length rather than on overall height. Both support the necks-for-sex idea. Neither study, however, allows us to refute one of the two ideas. We suggest new approaches for quantifying the relative importance of the two hypotheses. A direct analysis of selection pressure on neck length via survival and reproduction should clarify the mechanism maintaining the trait, while we predict that short robust ossicones should have arisen concurrently with incipient neck elongation if sexual selection was the main selective driver. The main challenge for the competing browser hypothesis is to explain why giraffe have remained about 2 m taller than their tallest competitors for over 1 Myr, whereas the sexual selection hypothesis cannot provide an adaptive explanation for the long neck of female giraffe. We conclude that probably both mechanisms have contributed to the evolution and maintenance of the long neck, and their relative importance can be clarified further. [source] Linear system solution by null-space approximation and projection (SNAP)NUMERICAL LINEAR ALGEBRA WITH APPLICATIONS, Issue 1 2007M. Ili Abstract Solutions of large sparse linear systems of equations are usually obtained iteratively by constructing a smaller dimensional subspace such as a Krylov subspace. The convergence of these methods is sometimes hampered by the presence of small eigenvalues, in which case, some form of deflation can help improve convergence. The method presented in this paper enables the solution to be approximated by focusing the attention directly on the ,small' eigenspace (,singular vector' space). It is based on embedding the solution of the linear system within the eigenvalue problem (singular value problem) in order to facilitate the direct use of methods such as implicitly restarted Arnoldi or Jacobi,Davidson for the linear system solution. The proposed method, called ,solution by null-space approximation and projection' (SNAP), differs from other similar approaches in that it converts the non-homogeneous system into a homogeneous one by constructing an annihilator of the right-hand side. The solution then lies in the null space of the resulting matrix. We examine the construction of a sequence of approximate null spaces using a Jacobi,Davidson style singular value decomposition method, called restarted SNAP-JD, from which an approximate solution can be obtained. Relevant theory is discussed and the method is illustrated by numerical examples where SNAP is compared with both GMRES and GMRES-IR. Copyright © 2006 John Wiley & Sons, Ltd. [source] Predictions of peptides' retention times in reversed-phase liquid chromatography as a new supportive tool to improve protein identification in proteomicsPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 4 2009Tomasz B, czek Dr. Abstract One of the initial steps of proteomic analysis is peptide separation. However, little information from RP-HPLC, employed for peptides separation, is utilized in proteomics. Meanwhile, prediction of the retention time for a given peptide, combined with routine MS/MS data analysis, could help to improve the confidence of peptide identifications. Recently, a number of models has been proposed to characterize quantitatively the structure of a peptide and to predict its gradient RP-HPLC retention at given separation conditions. The chromatographic behavior of peptides has usually been related to their amino acid composition. However, different values of retention coefficients of the same amino acid in different peptides at different neighborhoods were commonly observed. Therefore, specific retention coefficients were derived by regression analysis or by artificial neural networks (ANNs) with the use of a set of peptides retention. In the review, various approaches for peptide elution time prediction in RP-HPLC are presented and critically discussed. The contribution of sequence dependent parameters (e.g., amphipathicity or peptide sequence) and peptide physicochemical descriptors (e.g., hydrophobicity or peptide length) that have been shown to affect the peptide retention time in LC are considered and analyzed. The predictive capability of the retention time prediction models based on quantitative structure,retention relationships (QSRRs) are discussed in details. Advantages and limitations of various retention prediction strategies are identified. It is concluded that proper processing of chromatographic data by statistical learning techniques can result in information of direct use for proteomics, which is otherwise wasted. [source] Combining experimental data for structure determination of flexible multimeric macromolecules by molecular replacementACTA CRYSTALLOGRAPHICA SECTION D, Issue 5 2006Stefano Trapani A major effort has been made by the structural biology community to develop user-friendly software for the use of biologists. However, structural projects become more and more challenging and their solution often relies on a combination of information from various sources. Here, it is described how X-ray data, normal-mode analysis (NMA) and electron-microscopy (EM) data can be successfully combined in order to obtain a molecular-replacement (MR) solution for crystal structures containing multimeric molecules. NMA is used to simulate computationally the inherent internal flexibility of the monomer and thus enhance, together with the crystal noncrystallographic symmetry (NCS), the MR capabilities. NCS is also used to obtain a reliable EM reconstruction, which is then employed as a filter to construct oligomers starting from monomers. The feasibility of the direct use of EM reconstructions as a template for MR when the X-ray and EM data resolutions overlap is also discussed. [source] Direct use of vegetable oil and animal fat as alternative fuel in internal combustion engineBIOFUELS, BIOPRODUCTS AND BIOREFINING, Issue 2 2008Pinaki Mondal Abstract Gradual depletion of world petroleum reserves and the impact of environmental pollution of increasing exhaust emissions lead to the search for a suitable alternative fuels for diesel engines. The substitution of conventional fuels (gasoline, diesel) by renewable biofuels is considered a potential way to reduce pollution and to support the sustainable development of a country. Direct use of vegetable oil and animal fat is a promising alternative to solve these problems. An exhaustive review of the experiments in this area, carried out by several researchers in last three decades, is presented here. Different problems associated with the direct use of vegetable oil and animal fat and potential solutions from both public and private sectors are discussed. Some engine manufacturers have started to launch full-warranty engines with vegetable oil as fuel. It is expected that the competitive engine market will witness more intense research, resulting in the launch of more vegetable-oil engines with full warranties. The steep rise in food prices in recent years is concerning policy-makers and has raised the old ,food vs fuel' debate. It has been concluded that vegetable oil can probably only substitute small to medium portions of petroleum-based fuel due to future severe land-usage competition from food sector. This calls for intense research initiatives into the production of suitable fuel from non-edible vegetable oil, grown in wasteland. In this regard, genetic engineering may prove to be extremely effective in developing ,designer fuel'. © 2008 Society of Chemical Industry and John Wiley & Sons, Ltd [source] Combining Information from Cancer Registry and Medical Records Data to Improve Analyses of Adjuvant Cancer TherapiesBIOMETRICS, Issue 3 2009Yulei He Summary Cancer registry records contain valuable data on provision of adjuvant therapies for cancer patients. Previous studies, however, have shown that these therapies are underreported in registry systems. Hence direct use of the registry data may lead to invalid analysis results. We propose first to impute correct treatment status, borrowing information from an additional source such as medical records data collected in a validation sample, and then to analyze the multiply imputed data, as in Yucel and Zaslavsky (2005,,Journal of the American Statistical Association,100, 1123,1132). We extend their models to multiple therapies using multivariate probit models with random effects. Our model takes into account the associations among different therapies in both administration and probability of reporting, as well as the multilevel structure (patients clustered within hospitals) of registry data. We use Gibbs sampling to estimate model parameters and impute treatment status. The proposed methodology is applied to the data from the Quality of Cancer Care project, in which stage II or III colorectal cancer patients were eligible to receive adjuvant chemotherapy and radiation therapy. [source] Irrungen und Wirrungen um Biokraftstoffe.CHEMIE IN UNSERER ZEIT (CHIUZ), Issue 5 2010Biokraftstoffe sind nicht per se nachhaltig Die jährliche Photosyntheseleistung auf der Erde übersteigt die anthropogene CO2 -Produktion. Dies legt eine energetische Nutzung der Biomasse nahe und hat die Entwicklung von Biokraftstoffen erheblich gefördert. In vielen Fällen verstößt die Nutzung von Biokraftstoffen jedoch gegen Prinzipien der Nachhaltigkeit. Für die Deckung des Weltenergiebedarfes durch Biomasse würde die gesamte verfügbare landwirtschaftliche Nutzfläche benötigt. Diese Einsicht hat eine kritische Teller-oder-Tank-Diskussion ausgelöst. Energetisch und ökologisch effizienter als die Nutzung von Biokraftstoffen wäre der Anbau schnellwachsender Hölzer und deren direkte Verstromung im Kraftwerk. Die mit großem Abstand effizienteste Nutzung der Sonnenenergie erlauben Photovoltaik und Solarthermie. Wegen ihrer hohen Energiedichte werden flüssige Biokraftstoffe der zweiten Generation aber dort, wo die Elektromobilität an Grenzen stößt, auch in Zukunft Anwendung finden. The annual photosynthesis on the Earth exceeds the anthropogenic CO2 production. This suggests an energetic use of biomass and has greatly promoted the development of biofuels. In many cases, however, the use of biofuels is breaking the rules of sustainability. To meet the world's energy demand from biomass would require the total available agricultural land. This insight has a critical plate or tank discussion triggered. Energetically and environmentally more efficient than the use of biofuels would be the cultivation of fast-growing timber and its direct use in coal power plants for electricity production. By far the most efficient use of solar energy is provided by photovoltaic and solar heat use. Because of their high energy density liquid second-generation biofuels will be applied also in future in such cases where electrical mobility has its limits. [source] | ||||||||||||||||||||||