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Over the past decade, the exponential growth in the production of bio-mass for energy use has raised concerns as to the environmental impacts of this type of land use, as well as the potential land-use changes (LUC) associated with an extension of agricultural land areas. Determining the environmental impacts of an expanding bioenergy sector requires reconstructing the chains of cause and effect from the determinants of land-use change (both direct and indirect) and land-use practices through to the impacts of those practices. Conducting an exhaustive litera-ture review from 1975 to 2014, we identified 241 articles relevant to this causal chain, thus enabling an analysis of the environmental impacts of LUC for bioenergy. This chapter presents the results of a detailed literature analysis and literature review of the 52 articles within this corpus specifically addressing impacts on soils. The variation in soil organic carbon (SOC) is the most commonly used impact indicator, followed by soil loss to erosion and, to a lesser extent, the potential for environmen-tal acidification as determined by life-cycle assessments. Background and transi-tional SOC levels during LUC affect the predictive value of estimated final SOC variations but are not generally accounted for in default static stock-difference approaches. Perennial crops tend to be better at maintaining or even improving SOC levels, but results vary according to pedoclimatic and agronomic conditions. The mechanisms involved notably include protection of the soil surface with a dense perennial cover and the limitation of tillage operations, especially deep plowing; accumulation of organic matter and SOC linked to biomass production, especially belowground production of rhizomes and deep, dense root systems; associated reductions in nutrient loss via runoff and erosion. Nevertheless, additional research is needed to improve our understanding of and ability to model the full range of processes underlying soil quality and LUC impacts on soil quality.

AbstractFullerene derivatives functionalized with isomeric phenyleneethynylene‐based dendrons possessing either 1,3,5‐triethynylbenzene or 1,2,4‐triethynylbenzene branching units have been prepared. The electrochemical properties of these compounds are not strongly dependent on the branching patterns since the corresponding redox processes are localized either on the C60 cage (acceptor unit) or on the dialkyloxybenzene moieties (donor units) at the dendron periphery. The photophysical investigations performed in CH2Cl2 have revealed an ultrafast dendron → C60 energy transfer in all these hybrid systems. Importantly, the different π‐conjugation patterns in the two series have a dramatic effect on their electronic properties as attested by the differences observed in their absorption and emission spectra. The lower lying absorption onset and the wider spectral profile of the dyads with 1,2,4‐triethynylbenzene branching units when compared to their 1,3,5‐triethynylbenzene analogues clearly points out an improved light harvesting capability. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Summary Plants adapt phenotypically to different conditions of light and nutrient supply, supposedly in order to achieve colimitation of these resources. Their key variable of adjustment is the ratio of leaf area to root length, which relies on plant biomass allocation and organ morphology. We recorded phenotypic differences in leaf and root mass fractions (LMF, RMF), specific leaf area (SLA) and specific root length (SRL) of 12 herbaceous species grown in factorial combinations of high/low irradiance and fertilization treatments. Leaf area and root length ratios, and their components, were influenced by nonadditive effects between light and nutrient supply, and differences in the strength of plant responses were partly explained by Ellenberg's species values representing ecological optima. Changes in allocation were critical in plant responses to nutrient availability, as the RMF contribution to changes in root length was 2.5× that of the SRL. Contrastingly, morphological adjustments (SLA rather than LMF) made up the bulk of plant response to light availability. Our results suggest largely predictable differences in responses of species and groups of species to environmental change. Nevertheless, they stress the critical need to account for adjustments in below‐ground mass allocation to understand the assembly and responses of communities in changing environments.

There remains conflicting evidence on the relationship between P supply and biological N(2)-fixation rates, particularly N(2)-fixing plant adaptive strategies under P limitation. This is important, as edaphic conditions inherent to many economically and ecologically important semi-arid leguminous tree species, such as Acacia senegal, are P deficient. Our research objective was to verify N acquisition strategies under phosphorus limitations using isotopic techniques. Acacia senegal var. senegal was cultivated in sand culture with three levels of exponentially supplied phosphorus [low (200 μmol of P seedling(-1) over 12 weeks), mid (400 μmol) and high (600 μmol)] to achieve steady-state nutrition over the growth period. Uniform additions of N were also supplied. Plant growth and nutrition were evaluated. Seedlings exhibited significantly greater total biomass under high P supply compared to low P supply. Both P and N content significantly increased with increasing P supply. Similarly, N derived from solution increased with elevated P availability. However, both the number of nodules and the N derived from atmosphere, determined by the (15)N natural abundance method, did not increase along the P gradient. Phosphorus stimulated growth and increased mineral N uptake from solution without affecting the amount of N derived from the atmosphere. We conclude that, under non-limiting N conditions, A. senegal N acquisition strategies change with P supply, with less reliance on N(2)-fixation when the rhizosphere achieves a sufficient N uptake zone.

Energy storage can facilitate the transition process from the actual energetic model to a model based on renewable energies. A lot of attention has been put in such technology, being the use of phase change materials (PCM) of high interest. However, design methodologies for PCM storage systems are still a limiting factor for its deployment. This paper compiles and structures the most common and promising design methodologies and highlights their usefulness and limitations. These methodologies are classified in six types: (1) empirical correlations and characterizing parameters, (2) dimensional analysis and correlations, (3) effectiveness–NTU, (4) Log Mean Temperature Difference (LMTD), (5) Conduction Transfer Functions (CTF), and (6) numerical models. Dimensionless correlations and effectiveness–NTU are the most common and straight-forward methods as well as the ones that offer more possibilities for general solutions. Empirical correlations and numerical models are problem based and difficult to generalize. On the other hand, the adaptation of LMTD and CTF to PCM systems still requires detailed research.

This work examines the effect of both absolute pressure (range 1–6 bar) and peak temperature (range 350–800 °C) during pyrolysis of acacia wood in a macro-TG on the yield and CO2 gasification reactivity of the resulting charcoal. A central composite design was used for the experiments. The results of statistical analyses showed satisfactory agreement between the experimental results (charcoal yield and charcoal CO2 gasification reactivity) and model predictions. Both charcoal yield and reactivity decreased with an increase in temperature but increased with an increase in pressure. An increase in pyrolysis pressure increased charcoal yield and decreased reactivity. The temperature had a more significant effect on charcoal reactivity than pressure, and their interaction was not significant. The optimal conditions for the preparation of reductant charcoal were found to be a peak pyrolysis temperature of 617 °C and an absolute pressure of 6 bar.

This paper discusses the oil palm expansion in the State of Para, located in the Brazilian Amazon. It focuses on land use change aspects put in perspective with the sustainability criteria for biofuels of the European Renewable Energy Directive (RED). The study shows that palm oil production for energy purposes appears very promising in Brazil. In parallel to local targets, the mandatory European biofuel targets represent an important market potential for the country. It seems too early to know whether the export of palm oil biodiesel from Brazil to Europe will be significant or not. However, it is likely that palm oil exports for biodiesel production in Europe occur in the coming years. Although the RED includes some essential conditions for sustainable production of biofuels, we argue that the values imposed for calculating carbon stocks do not reflect diversity of pastureland where oil palm expansion occurs in the Brazilian Amazon. The use of certain land areas authorised within the RED may also represent a significant limit in terms of biodiversity protection. This study provides new insights that may be used to improve life cycle assessment of biodiesel from palm oil in order to avoid unintended policy consequences.

Abstract A comprehensive non-isothermal, three-dimensional computational model of a polymer electrolyte membrane (PEM) fuel cell has been developed. The model incorporates a complete cell with both the membrane-electrode-assembly (MEA) and the gas distribution flow channels. With the exception of phase change, the model accounts for all major transport phenomena. The model is implemented into a computational fluid dynamics code, and simulations are presented with an emphasis on the physical insight and fundamental understanding afforded by the detailed three-dimensional distributions of reactant concentrations, current densities, temperature and water fluxes. The results show that significant temperature gradients exist within the cell, with temperature differences of several degrees K within the MEA. The three-dimensional nature of the transport is particularly pronounced under the collector plates land area and has a major impact on the current distribution and predicted limiting current density.