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This contribution presents the state of the art of economy-wide material flow accounting. Starting from a brief recollection of the intellectual and policy history of this approach, we outline system definition, key methodological assumptions, and derived indicators. The next section makes an effort to establish data reliability and uncertainty for a number of existing multinational (European and global) material flow accounting (MFA) data compilations and discusses sources of inconsistencies and variations for some indicators and trends. The results show that the methodology has reached a certain maturity: Coefficients of variation between databases lie in the range of 10% to 20%, and correlations between databases across countries amount to an average R2 of 0.95. After discussing some of the research frontiers for further methodological development, we conclude that the material flow accounting framework and the data generated have reached a maturity that warrants material flow indicators to complement traditional economic and demographic information in providing a sound basis for discussing national and international policies for sustainable resource use.
The North African countries Morocco, Algeria, Tunisia, Libya and Egypt have been and are currently experiencing rapid growth in energy demand. This development confronts their political leaders with the question of how to expand or diversify their countries' generation capacities. In this context, renewable energies and nuclear power constitute options that have rarely been exploited so far in the region. This article analyzes the drawbacks and benefits of both alternatives, with a special focus on import and export dynamics. When attempting to make the strategic decision between renewables and atomic power, North African regional specifics and circumstances have to be taken into account. Hence, in a first step, the article characterizes the energy systems of the North African countries and presents scenarios for their future development. In a second step, it scrutinizes the energy challenges these states face in terms of domestic concerns and foreign affairs. Finally, a case study of Algeria is used to demonstrate how renewable energies, but not nuclear power, are able to respond to North African energy challenges.
During the last century, the consumption of materials for human needs increased by several orders of magnitude, even for non-renewable materials such as metals. Some data on annual consumption (input) and recycling/waste (output) can often be found in the federal statistics, but a clear picture of the main flows is missing. A dynamic material flow model is developed for the example of copper in Switzerland in order to simulate the relevant copper flows and stocks over the last 150 years. The model is calibrated using data from statistical and published sources as well as from interviews and measurements. A simulation of the current state (2000) is compared with data from other studies. The results show that Swiss consumption and losses are both high, at a level of about 8 and 2 kg/(cap year), respectively, or about three times higher than the world average. The model gives an understanding of the flows and stocks and their interdependencies as a function of time. This is crucial for materials whose consumption dynamics are characterised by long lifetimes and hence for relating the current output to the input of the whole past. The model allows a comprehensive discussion of possible measures to reduce resource use and losses to the environment. While increasing the recycling reduces losses to landfill, only copper substitution can reduce the different losses to the environment, although with a time delay of the order of a lifetime.
Biogas and bio-methane that are based on energy crops are renewable energy carriers and therefore potentially contribute to climate protection. However, significant greenhouse gas emissions resulting from agricultural production processes must be considered, mainly resulting from agricultural production processes, as fertilizer use, pesticide etc.
This paper provides an integrated life cycle assessment (LCA) of biogas (i.e. bio-methane that has been upgraded and injected into the natural gas grid), taking into account the processes of fermentation, upgrading and injection to the grid for two different types of biogas plants thus examining the current state of the art as well as new, large-scale plants, operated by industrial players. Not only technical and engineering aspects are taken into account here, but also the choice of feedstock which plays an important role as to the overall ecological evaluation of bio-methane.
The substrates evaluated in this paper - aside from maize - are rye, sorghum, whole-crop-silage from triticale and barley, and the innovative options of agricultural grass (Landsberger Gemenge, a mixture of hairy vetch (vicia villosa), crimson clover (trifolium incarnátum) and Italian ryegrass (lolium multiflorum)) as well as a combination of maize and sunflower.
Resultado de la intervención intensiva antropogénica, la subcuenca ahora enfrenta serios problemas como la degradación de los suelos, deforestación y contaminación del agua. Estos impactos ambientales han provocado escasez del agua y disminución de su calidad a lo largo del transcurso del río y sus afluentes afectando la producción agropecuaria tanto como los ecosistemas dependientes del agua. Reconociendo estos problemas la administración municipal llegó a priorizar el territorio de la subcuenca. En este se promovió un proceso de concertación con actores locales de la subcuenca del Gil González con el fin de definir zonas de conservación, regeneración natural y fomento de sistemas de producción agrícola sostenible. Como mecanismo para promover estas medidas se estableció el Proyecto de Pagos por Servicios Ambientales Hídricos (PPSA-H) en la subcuenca del Río Gil González en el año 2007, lo cual forma parte del Programa Manejo Sostenible de los Recursos Naturales y Fomento de las Competencias Empresariales de la Cooperación Técnica Alemana (GIZ GmbH) en Nicaragua. El concepto de Pago por Servicios Ambientales Hídircos (PSA-H) esta aplicado como un mecanismo de incentivos financieros. Los planteamientos generales de la investigación están relacionados al concepto de PSA-H como una herramienta para la gestión integral de cuencas hidrográficas. Aparte de los planteamientos generales esta investigación trata de verificar específicamente la eficacia de la implementación del Proyecto de Pagos por Servicios Ambientales Hídricos (PSA-H) en la Subcuenca del Gil González como un caso de estudio.