a distribution company energy acquisition market model with integration of distributed generation and load curtailment options this work presents a novel day ahead energy acquisition model for a distribution company disco in a competitive market based on pool and financial bilateral contracts the market structure encompasses wholesale generation companies distributed generation dg units of independent producers dg units owned by the disco and load curtailment options thus while satisfying its technical constraints the disco purchases active and reactive power according to the offers of dg units customers and the wholesale market the resulting optimal power flow model is implemented with an object oriented approach which is solved numerically by making use of a branch and border sequential quadratic programming algorithm the model is validated in test systems and then applied to a real case study results show the general applicability of the proposed model with potential cost savings for the disco finally the analysis of lagrange multipliers gives valuable information which can be used to improve the market design and to extend the use of the model to a more general market structure such as a power exchange

a multiperiod energy acquisition model for a distribution company with distributed generation and interruptible load this paper presents a multiperiod energy acquisition model for a distribution company disco with distributed generation dg and interruptible load il in a day ahead electricity market assuming that cost information for individual generation companies gencos and discos is known the disco s energy acquisition strategy is modeled as a bilevel optimization problem with the upper subproblem representing individual discos and the lower subproblem representing the independent system operator iso the upper subproblem maximizes individual discos revenues the lower subproblem simulates the iso s market clearing problem that minimizes generation costs and compensation costs for interrupting load the bilevel problem is solved by a nonlinear complementarity method an 8 bus system is employed to illustrate the proposed model and algorithm in particular the roles of dgs and ils to alleviate congestion are analyzed

risk constrained portfolio selection of renewable sources in hydrothermal electricity markets renewable sources have recently emerged as a generation option for many countries in order to promote clean energy development in the case of brazil small hydro plants and cogeneration from sugarcane waste bagasse have been attractive alternatives during the past years with hundreds of mw installed since 2004 despite their advantages both alternatives are hindered by seasonal yet complementary availability this forces producers to discount or price the risks faced when selling firm energy contracts and may ultimately lead to projects being commercially unattractive we propose a stochastic optimization model that defines the optimal composition of a portfolio based on these two renewable sources in order to maximize the revenue of an energy trading company at the same time this model mitigates hydrological and fuel unavailability risks thus allowing the participation of both sources in the forward market environment in a competitive manner a case study is presented based on data from the brazilian system

forward contracting and selling price determination for a retailer to procure the electric energy to be sold to its clients a retailer has to face two major difficulties while buying electric energy it must cope with uncertain pool prices or sign forward contracts at higher average prices while selling electricity it should handle the uncertainty of the end user demand and the fact that customers might choose a different retailer if the selling price is not competitive enough we propose a risk constrained stochastic programming framework to decide which forward contracts the retailer should sign and at which price it must sell electricity so that its expected profit is maximized at a given risk level the developed model takes into account the elastic behavior of end users with respect to the selling price offered by the retailer a realistic case study illustrates the methodology proposed

conditional cash transfers schooling and child labor micro simulating brazil s bolsa escola program a growing number of developing economies are providing cash transfers to poor people that require certain behaviors on their part such as attending school or regularly visiting health care facilities a simple ex ante methodology is proposed for evaluating such programs and used to assess the bolsa escola program in brazil the results suggest that about 60 percent of poor 10 to 15 year olds not in school enroll in response to the program the program reduces the incidence of poverty by only a little more than one percentage point however and the gini coefficient falls just half a point results are better for measures more sensitive to the bottom of the distribution but the effect is never large

a comparison of var and cvar constraints on portfolio selection with the mean variance model in this paper we analyze the portfolio selection implications arising from imposing a value at risk var constraint on the mean variance model and compare them with those arising from the imposition of a conditional value at risk cvar constraint we show that for a given confidence level a cvar constraint is tighter than a var constraint if the cvar and var bounds coincide consequently a cvar constraint is more effective than a var constraint as a tool to control slightly risk averse agents but in the absence of a risk free security has a perverse effect in that it is more likely to force highly risk averse agents to select portfolios with larger standard deviations however when the cvar bound is appropriately larger than the var bound or when a risk free security is present a cvar constraint dominates a var constraint as a risk management tool

representing the valuation of take or pay provisions in gas markets with limited liquidity long term contracting is the traditional governance mechanism to deal with the transaction costs associated with the specificity of gas industry assets long term contracts have been often used to allocate risks among players and to that end they often include take or pay provisions these clauses specify that buyers take the volume risk as they are obliged to pay for a minimum amount of gas consumption in exchange buyers pay a predefined price supposedly lower than the risk neutral expectation of short term gas prices in that view if the buyer is able to resell that gas in the short term the contract is an effective hedge against short term volatility otherwise the contract does not act as a hedge but it becomes a sunk cost the corresponding power producers behavior involves not only output decisions but also financial decisions to analyze that situation this paper develops a new quantitative methodology that allows comparing risk neutral valuations of gas and power markets decisions we test the model in a real size system and show the additional cost of the power system associated with a possible illiquidity of the short term gas market

pricing flexible natural gas supply contracts under uncertainty in hydrothermal markets the worldwide development of the natural gas industry resulted in an integration process between electrical and gas sectors in several countries in brazil this process has been taking place in a consistent manner especially on account of the increase in gas consumption for industrial use and of the installation of thermoelectric plants due to the predominance of hydro plants in electric power generation thermoelectric energy production is basically dependent on hydrology and as a result presents a wide annual variability consequently the investment applied to gas production and transportation infrastructure may become under utilized during a large part of the time thus it is important to find mechanisms apt to improve its utilization in this respect the present work investigates the creation of a flexible market for gas where contracts for flexible gas supply would be offered to industrial users who would receive the gas assigned to thermal power plants when the latter are not dispatched and would resort to an alternate fuel when these plants are dispatched the attractiveness of such a contract would depend of course on its price the purpose of this work is to develop a stochastic model for pricing flexible gas supply contracts taking into account the uncertainty associated to the supply dependent on the dispatch of the thermal power plants which have the priority of use of the gas and the risk profile of potential consumers

in the same boat but not equals the heterogeneous effects of parental income on child labour this paper examines the impact of parental income on child labour the empirical literature has found conflicting results regarding whether poverty leads parents to send their children to work mos

markets and pricing for interruptible electric power a market is proposed for interruptible or callable forward contracts for electric power in which the consumer grants the power supplier the right to interrupt a given unit of load in return for a price discount the callable forward contracts are traded continuously until the time of use this allows recourse for those customers with uncertain demand while risk averse consumers can minimize their price risk by purchasing early callable forward contracts are simple in form and can be directly incorporated into the utility s economic dispatch procedure

child labor cause consequence and cure with remarks on international labor standards although the literature on child labor is enormous it lacks a common theoretical foundation in this paper analytical survey of this field is provided keeping in mind that this is an area where the primary reason for theorizing is ultimately to influence policy overall it is noted that the literature on child labor is an illustration of abundance and anarchy although empirical writings on child labor are numerous they are not usually founded on theory it is argued that there is much that can be done in curbing the issue of child labor several theories were studied in this paper including collaborative intervention such efforts include public action which alters the economic environment such that the parents of their own accord prefer to withdraw the child from labor force another strategy involves the government a legal intervention is enforcing a total ban on the subject although such interventions have good intentions some of them may not be feasible in general it is better to take economy wide measures against child labor and if there is to be a sector specific ban it should be based on the working conditions of that sector rather than the destination of the goods

is child labor inefficient we build a model of child labor and study its implications for welfare we assume that there is a trade off between child labor and the accumulation of human capital even if parents are altruistic and child labor is socially inefficient it may arise in equilibrium because parents fail to fully internalize its negative effects this occurs when bequests are zero or when capital markets are imperfect we also study the effects of a simple ban on child labor and derive conditions under which it may be pareto improving in general equilibrium we show that the implications of child labor for fertility are ambiguous

the policy analysis of child labor a comparative study the policy analysis of child labour c grootaert h a patrinos modelling the determinants of child labour c grootaert child labour in cote d ivoire k cartwright child labour in urban bolivia k cartwright h a patrinos child labour in the philippines c sakellariou a lall policies to reduce child labour c grootaert h a patrinos

household income as a determinant of child labor and school enrollment in brazil evidence from a social security reform abstractthis article studies the effects of household income on labor participation and school enrollment of children aged 10 14 in brazil using a social security reform as a source of exogenous variation in household income i find that increased benefits are associated with increases in school enrollment for girls as well as a smaller reduction in their labor participation but i find no effects for boys i also uncover evidence that the gender of the benefit receiver matters for girls labor variables only benefits received by females reduce girls work

interruptible electricity contracts from an electricity retailer s point of view valuation and optimal interruption we consider interruptible electricity contracts issued by an electricity retailer that allow for interruptions to electric service in exchange for either an overall reduction in the price of electricity delivered or for financial compensation at the time of interruption we provide a structural model to determine electricity prices based on stochastic models of supply and demand we use stochastic dynamic programming to value interruptible contracts from the point of view of an electricity retailer and describe the optimal interruption strategy we also demonstrate that structural models can be used to value contracts in competitive markets our numerical results indicate that in a deregulated market interruptible contracts can help alleviate supply problems associated with spikes of price and demand and that competition between retailers results in lower value and less frequent interruption

sri lanka can conditional cash transfer programs serve as safety nets in keeping children at school and from working when exposed to shocks this brief summarizes the results of a gender impact evaluation study can conditional cash transfer cct programs serve as safety nets in keeping children at school and from working when exposed to shocks conducted the program started in 1997 and still exists today in sri lanka the study observed that income shocks on poor households are known to induce parents to take their children out of school and send them to work when other risk coping instruments are insufficient cct programs where the condition is on school attendance have been shown to be effective in increasing educational achievements and reducing child work shocks are highly prevalent and children have irregular periods of school enrollment children who are taken out of school are less likely to re enroll

child labour in indonesian small industries abstract we analyse the geographic incidence of child labour in small manufacturing firms in indonesia at the village level our unique data set covers virtually all indonesian villages and urban neighbourhoods it allows us to distinguish between demand and supply side determinants of child labour we show by correcting for sample selection that a number of counterintuitive results child labour being unaffected by credit access and school proximity are the result of an interplay between supply and demand side determinants credit access and school proximity reduce child labour supply but simultaneously constitute positive location factors for firms thereby increasing the demand for child labourers to effectively reduce child labour growth oriented policies such as enhancing school and credit facilities should be complemented by policies specifically geared towards increasing school attendance

strategic management of multi year natural gas contracts in electricity markets combined cycle gas turbine ccgt plants show some advantages such as better economies of scale or lower co2 emission rates in comparison to other technologies in addition due to their flexible operation ccgt plants are a useful support for the integration of the growing renewable energy installed capacity consequently during the last years ccgt plants have proliferated in electricity systems increasing the global demand of natural gas ng in order to guarantee the ng supply and to hedge the price volatility electricity generation companies gencos sign supply contracts with ng producers typically ng producers force long term contracts in order to recover their huge capital investments therefore gencos should optimize the exercise of the supply contracts in the long term scope in order to maximize their profits in the electricity market however the optimal exercise of the supply contracts on behalf of the gencos could be impeded because of possible bottlenecks in the ng system accordingly this paper proposes a methodology to incorporate both the characteristics of ng supply contracts and the congestions in the ng system in an electricity market model that could support the decision making process on behalf of the gencos a study case illustrates the methodology

mobility and the return to education testing a roy model with multiple markets self selected migration presents one potential explanation for why observed returns to a college education in local labor markets vary widely even though u s workers are highly mobile to assess the impact of self selection on estimated returns this paper first develops a roy model of mobility and earnings where workers choose in which of the 50 states plus the district of columbia to live and work available estimation methods are either infeasible for a selection model with so many alternatives or place potentially severe restrictions on earnings and the selection process this paper develops an alternative econometric methodology that combines lee s 1983 parametric maximum order statistic approach to reduce the dimensionality of the error terms with more recent work on semiparametric estimation of selection models e g ahn and powell 1993 the resulting semiparametric correction is easy to implement and can be adapted to a variety of other polychotomous choice problems the empirical work which uses 1990 u s census data confirms the role of comparative advantage in mobility decisions the results suggest that self selection of higher educated individuals to states with higher returns to education generally leads to upward biases in ols estimates of the returns to education in state specific labor markets while the estimated returns to a college education are significantly biased correcting for the bias does not narrow the range of returns across states consistent with the finding that the corrected return to a college education differs across the u s the relative state to state migration flows of college versus high school educated individuals respond strongly to differences in the return to education and amenities across states

collective labor supply and welfare the paper develops a general collective model of household labor supply in which agents are characterized by their own possibly altruistic preferences and household decisions are only assumed to be pareto efficient an alternative interpretation is that there are two stages in the internal decision process agents first share nonlabor income according to some given sharing rule then each one optimally chooses his or her own labor supply and consumption this setting is shown to generate testable restrictions on labor supplies moreover the observation of labor supply behavior is sufficient for recovering individual preferences and the sharing rule up to a constant finally the traditional tools of welfare analysis can be adapted to the new setting

effects of public policy on child labor current knowledge gaps and implications for program design many policy instruments can be used to address or affect child labor even if they are implemented to achieve other objectives from a theoretical point of view however the impact of these policies on child labor is undetermined this paper discusses the evidence generated by rigorous evaluations on the impact on child labor of labor market programs conditional and unconditional transfers and microcredit among other social programs and interventions the study finds that although transfer programs generally tend to reduce child labor other policies risk increasing child labor especially if they affect households productive opportunities the findings also point to knowledge gaps that should be addressed in future evaluations while progress has been made over the past decade there is still much to learn about the effects of public policy on the labor participation of many children in developing countries

a review and comparison of tests of cross section independence in panels abstract in this paper we review and compare diagnostic tests of cross section independence in the disturbances of panel regression models we examine tests based on the sample pairwise correlation coefficient or on its transformations and tests based on the theory of spacings the ultimate goal is to shed some light on the appropriate use of existing diagnostic tests for cross equation error correlation our discussion is supported by means of a set of monte carlo experiments and a small empirical study on health results show that tests based on the average of pairwise correlation coefficients work well when the alternative hypothesis is a factor model with non zero mean loadings tests based on spacings are powerful in identifying various forms of strong cross section dependence but have low power when they are used to capture spatial correlation

does child labour displace schooling evidence on behavioral responses to an enrollment subsidy this brief summarizes the results of a gender impact evaluation study entitled does child labour displace schooling evidence on behavioral responses to an enrollment subsidy conducted between 1995 and 1996 in bangladesh the study observed that the subsidy increases schooling but its effect on child labour is ambiguous the subsidy increased schooling by far more than it reduced child labour substitution effects helped protect current incomes from the higher school attendance induced by the subsidy substitution effects helped protect current incomes from the higher school attendance induced by the subsidy the reduction in the incidence of child labour by boys girls represents about one quarter eighth of the increase in their school enrollment rate

optimizing short term natural gas supply portfolio for electric utility companies natural gas fired power plants ngfpp are important electricity generation resources in the united states optimizing the natural gas supply portfolio especially the short term portfolio is critical for the day to day operations and the financial performance of ngfpps traditionally such optimization problems are solved using cost minimization based frameworks however such frameworks are facing challenges due to the lack of consideration of associated financial risks in the current deregulated electricity markets which the electric utility companies eucs who own and operate ngfpps now bear this paper presents a utility maximization based framework to optimize the short term natural gas supply portfolio for the euc it considers the financial risks associated with the portfolio and incorporates the risk preferences of the eucs as decision maker dm in the portfolio optimization process an application of the proposed framework is provided and its results show that the proposed framework is more desirable in terms of risk cost trade off optimization

pricing flexible electricity contracts this paper is concerned with pricing of electricity contracts that allow flexible scheduling of the supply or demand of electric energy the contracts are priced based on the principle of no arbitrage variables of the contracts are used to determine arbitrage opportunities and the price of contracts pricing of flexible contracts involves a scheduling policy by representing the spot price with an appropriate stochastic process the scheduling policy can be found using stochastic dynamic programming simulation examples illustrate the tradeoffs between prices and scheduling flexibility