Teoria de carteiras e a alocação de parques eólicos offshore

The consumption of energy on the planet is currently based on fossil fuels. They are responsible for adverse effects on the environment. Renewables propose solutions for this scenario, but must face issues related to the capacity of the power supply. Wind energy offshore emerging as a promising alternative. The speed and stability are greater winds over oceans, but the variability of these may cause inconvenience to the generation of electric power fluctuations. To reduce this, a combination of wind farms geographically distributed was proposed. The greater the distance between them, the lower the correlation between the wind velocity, increasing the likelihood that together achieve more stable power system with less fluctuations in power generation. The efficient use of production capacity of the wind park however, depends on their distribution in marine environments. The objective of this research was to analyze the optimal allocation of wind farms offshore on the east coast of the U.S. by Modern Portfolio Theory. The Modern Portfolio Theory was used so that the process of building portfolios of wind energy offshore contemplate the particularity of intermittency of wind, through calculations of return and risk of the production of wind farms. The research was conducted with 25.934 observations of energy produced by wind farms 11 hypothetical offshore, from the installation of 01 simulated ocean turbine with a capacity of 5 MW. The data show hourly time resolution and covers the period between January 1, 1998 until December 31, 2002. Through the Matlab R software, six were calculated minimum variance portfolios, each for a period of time distinct. Given the inequality of the variability of wind over time, set up four strategies rebalancing to evaluate the performance of the related portfolios, which enabled us to identify the most beneficial to the stability of the wind energy production offshore. The results showed that the production of wind energy for 1998, 1999, 2000 and 2001 should be considered by the portfolio weights calculated for the same periods, respectively. Energy data for 2002 should use the weights derived from the portfolio calculated in the previous time period. Finally, the production of wind energy in the period 1998-2002 should also be weighted by 1/11. It follows therefore that the portfolios found failed to show reduced levels of variability when compared to the individual production of wind farms hypothetical offshore

Podem os programas sociais e de transferência de renda influenciar a oferta de trabalho em atividades não agrícolas? uma análise para as famílias em condição de pobreza no meio rural do nordeste

This study aims to analyze the main effect of social programs and cash transfers on the labor supply of non-farm family members in poverty in rural areas of the Northeast. Among the specific objectives, we sought to investigate the effects of these programs and individual characteristics on the decision of participation and allocation of working hours of parents and children in non-agricultural activities. It was assumed, as a theoretical basis, the model of neoclassical labor supply as well as the principle that the decision of allocation of working hours, non-agricultural, is subject to the initial choice of the worker devote or not the non-agricultural employment . The hypothesis assumes that access to social programs and income transfer contributes to the dismay of rural workers, in poverty, in its decision to participate and offer hours of work in non-agricultural activities. To achieve this objective, we applied the models of Heckman (1979) and Double Hurdle, of Cragg (1971), consisting of associating the decision to participate in the labor market with the decision on the amount of hours allocated. The database used was the National Survey by Household Sampling (PNAD) of 2006. The results of the heads of households showed that transfers of income, although they may have some effect on labor supply rural nonfarm, the magnitude has to say that there may be some dependence on benefits. The estimates for the joint children of 10 to 15 years showed that the programs have negatively influenced participation in suggesting an increase in school participation, although for the allocation of working hours the results were not significant on the incidence of child labor