285 research outputs found

    Improving Decision Making for Public R&D Investment in Energy: Utilizing Expert Elicitation in Parametric Models

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    Effective decision making to allocate public funds for energy technology research, development, and demonstration (R&D) requires considering alternative investment opportunities that can have large but highly uncertain returns and a multitude of positive or negative interactions. This paper proposes and implements a method to support R&D decisions that propagates uncertainty through an economic model to estimate the benefits of an R&D portfolio, accounting for innovation spillovers and technology substitution and complementarity. The proposed method improves on the existing literature by: (a) using estimates of the impact of R&D investments from one of the most comprehensive sets of expert elicitations on this topic to date; (b) using a detailed energy-economic model to estimate evaluation metrics relevant to an energy R&D portfolio: e.g., system benefits, technology diffusion, and uncertainty around outcomes; and (c) using a novel sampling and optimization strategy to calculate optimal R&D portfolios. This design is used to estimate an optimal energy R&D portfolio that maximizes the net economic benefits under an R&D budget constraint. Results parameterized based on expert elicitations conducted in 2009-2011 in the United States provide indicative results that show: (1) an expert-recommended portfolio in 2030, relative to the BAU portfolio, can reduce carbon dioxide emissions by 46 million tonnes, increase economic surplus by $29 billion, and increase renewable energy generation by 39 TWh; (2) uncertainty around the estimates of R&D benefits is large and overall uncertainty increases with greater investment levels; (3) a 10-fold expansion from 2012 levels in the annual R&D budget for utility-scale energy storage, bioenergy, advanced vehicles, fossil energy, nuclear energy, and solar photovoltaic technologies can be justified by returns to economic surplus; (4) the greatest returns to public R&D investment are in energy storage and solar photovoltaics; and (5) the current allocation of energy R&D funds is very different from optimal portfolios. Taken together, these results demonstrate the utility of applying new methods to improve the cost-effectiveness and environmental performance in a deliberative approach to energy R&D portfolio decision making

    Crianças em situaçāo de imigraçāo na escola publica: percepçōes de docentes = Immigrant children in public school: Perceptions of teachers = Scolarisation à l’école publique d’enfants en situation d’immigration: perception des enseignants = Niños inmigrantes en la escuela pública: percepciones del profesora

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    Este artigo apresenta uma pesquisa qualitativa sobre as percepções de docentes a respeito de crianças em situação de imigração ou de refúgio na escola pública, baseada na perspectiva crítica de educação intercultural e na concepção histórico-cultural. Foram realizadas entrevistas entre 2018 e 2019 com dez professores do Ensino Fundamental I de uma escola municipal de Duque de Caxias, Rio de Janeiro, com mais de doze anos de experiência na educação básica e que tiveram, em suas turmas, crianças congolesas ou angolanas. Identificamos que a presença de crianças em situação de imigração, que inicialmente se poderia constituir em um elemento dificultador para o processo de ensino-aprendizagem, tem sido um motor para novas reflexões sobre diferenças, desigualdades, preconceitos e discriminação no espaço escolar

    Characteristic length scale of the magnon accumulation in Fe3O4/Pt bilayer structures by incoherent thermal excitation

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    The dependence of Spin Seebeck effect (SSE) with the thickness of the magnetic materials is studied by means of incoherent thermal excitation. The SSE voltage signal in Fe3O4/Pt bilayer structure increases with the magnetic material thickness up to 100¿nm, approximately, showing signs of saturation for larger thickness. This dependence is well described in terms of a spin current pumped in the platinum film by the magnon accumulation in the magnetic material. The spin current is generated by a gradient of temperature in the system and detected by the Pt top contact by means of inverse spin Hall effect. Calculations in the frame of the linear response theory adjust with a high degree of accuracy the experimental data, giving a thermal length scale of the magnon accumulation (¿) of 17¿±¿3¿nm at 300¿K and ¿¿=¿40¿±¿10¿nm at 70¿K

    Substantial emission reductions from Chinese power plants after the introduction of ultra-low emissions standards

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    In 2014, China introduced an ultra-low emissions (ULE) standards policy for renovating coal-fired power-generating units to limit SO2, NOx and particulate matter (PM) emissions to 35, 50 and 10 mg m−3, respectively. The ULE standard policy had ambitious levels (surpassing those of all other countries) and implementation timeline. We estimate emission reductions associated with the ULE policy by constructing a nationwide, unit-level, hourly-frequency emissions dataset using data from a continuous emissions monitoring systems network covering 96–98% of Chinese thermal power capacity during 2014–2017. We find that between 2014 and 2017 China’s annual power emissions of SO2, NOx and PM dropped by 65%, 60% and 72%, respectively. Our estimated emissions using actual monitoring data are 18–92% below other recent estimates. We detail the technologies used to meet the ULE standards and the determinants of compliance, underscoring the importance of ex post evaluation and providing insights for other countries wishing to reduce their power emissions
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