The Limits of Bioenergy : A Complex Systems Approach to Land Use Dynamics and Constraints

This thesis aims to use a novel methodology to obtain an understanding of the potential limits of bioenergy by using a complex systems approach for assessing land use dynamics and constraints. Although bioenergy is classified as a renewable energy source, land is a finite resource and its expansion limited. The anthropogenic demands on land result from a combination of multiple provisioning services. These include global food consumption, dietary preference, crop and livestock yields, land use integration, wastes and residues, and bioenergy yields and forms, as well as the allocation of surplus land for forestry and energy crops, and the potential role of negative emission technologies. Thus, bioenergy is just one part of a complex land-use system. The general hypothesis is that there are fundamental limits to the overall scale and rate of the sustainable expansion of bioenergy, which can be assessed by means of combinations of empirical data, mapping tools and complex systems models. To this end, a novel methodological approach is proposed, which is based on a combination of two original models. The first one is termed the Global Calculator Land Use Change Model (GCLUC), developed as part of the Global Calculator Project, in which land is freely allocated worldwide and food security is assumed a priority. The second considers land for dedicated energy crops as a delimited reserve, by integrating Hubbert’s curve principles (originally proposed for peak oil assessments) in agro-ecological zoning schemes (as recently done for sugarcane ethanol in Brazil), resulting in a new model here termed green-Hubbert. The results show ranges of bioenergy potentials and expansion rates in the context of different land use futures. The potential public policies necessary to support sustainable bioenergy are also discussed. Finally, the conclusions show that, indeed, there are fundamental limits to bioenergy, and these limits are dynamic over time.Open Acces

Народна педагогіка в педагогічній спадщині Василя Сухомлинського

У статті автором відображено народознавчий аспект діяльності В. О.Сухомлинського, виокремлено прогресивні ідеї навчання й виховання дітей та молоді в сучасній національній школі

The Thermal Energy and the Energy Efficiency Paradox: Challenges for a New Paradigm of Energy Planning

O modelo brasileiro de geração de energia elétrica possui características muito peculiares em relação aos demais países do mundo. Seu vasto parque hidrelétrico possibilitou ao país utilizar indiscriminadamente a eletricidade em diversas formas de uso final. Porém, com a transição do modelo hídrico para um modelo misto de geração, surge um novo paradigma de eficiência energética. A eletricidade consumida em usos finais térmicos pode agora ser substituída por diferentes fontes energéticas de origem química, como o gás natural e a biomassa. Nesse novo cenário, a energia primária pode ser convertida tanto em energia elétrica, quanto em energia útil, na forma de calor. O objetivo desta pesquisa foi identificar a distorção presente no atual modelo energético nacional e avaliar o potencial de economia de energia primária possível de ser obtido pela substituição de eletricidade por fontes de origem química, em usos finais térmicos. A hipótese formulada é de que o uso racional da energia, segundo sua qualidade exergética e finalidade de uso, pode reduzir significativamente o consumo de energia primária. Para comprovar essa hipótese, foram realizadas estimativas de substituição de eletricidade por gás natural, nos usos finais térmicos de todos os setores de consumo. Além disso, foi realizada uma análise comparativa entre diversos países do mundo, quanto ao uso do calor em suas matrizes energéticas, a fim de estimar o percentual de eletricidade que poderia ser substituído no Brasil e a quantidade de energia química equivalente que seria demandada. Também foram estimados os possíveis ganhos ambientais decorrentes de tal substituição. Os resultados obtidos mostram a relevância do tema e o impacto que uma política de uso racional da energia poderia alcançar.The electrical generation model of Brazil has a peculiar characteristic regarding other countries. Its large hydropower capacity allowed the indiscriminate use of the electricity for several kinds of end uses. However, with the transition of the hydroelectric generation model for a mixed generation model, a new paradigm of energy efficiency appears. The electricity consumed in the thermal end uses can be now substituted by other energy sources like natural gas and biomass. In that new scenario, the primary energy can be converted in electricity as well as useful energy. The objective was to identify the existent distortion in the current Brazilian model and to evaluate the economy potential of primary energy that could be obtained substituting the electricity by chemical energy in thermal end uses. The formulated hypothesis is that the rational use of energy, according to its exergy quality and purpose of use, can reduce significantly the primary energy consumption. The substitution of electricity by natural gas was simulated for all the thermal end uses of the energy mix. Besides, a comparative analysis taking into account other countries was carried out about the use of heat in the energy mixes, in order to estimate the electricity percent that could be substituted in Brazil and the equivalent amount of chemical energy that would be demanded. The possible environmental gains promoted by that substitution was also estimated. The results show the relevance of the theme and the impact that a policy of energy efficiency could attain

Time and cognitive development: from Vygotsky’s thinking to different notions of disability in the school environment

Abstract The perceptions about the structure of time are deeply entrenched in people’s minds. As such, they do not reveal themselves directly but are mediated by how it is possible to articulate concepts that assume these perceptions. This paper assesses how the notion of time can affect cognitive development, looking at Vygotsky’s works on defectology and other references, given that there is a gap regarding this articulation in specialized literature. For this purpose, it is argued that the notion of time often departs from an equivocal assumption of a linear time structure, influencing how we lead with disability issues in teaching and learning processes. The findings also show some consequences of such a departure in the conceptualization of deficiency, development, and time to the issue of the visibility of the so-called deficient, particularly concerning the school environment