evaluating a stochastic programming based bidding model for a multireservoir system hydropower producers need to schedule when to release water from reservoirs and participate in wholesale electricity markets where the day ahead production is physically traded a mixed integer linear stochastic model for bid optimization and short term production allocation is developed and tested through a simulation procedure implemented for a complex real life river system the stochastic bid model sees uncertainty in both spot market prices and inflow to the reservoirs the same simulation procedure is also implemented for a practice based deterministic heuristic method similar to what is currently used for bid determination in the industry and the results are compared the stochastic approach gives improvements in terms of higher obtained average price and higher total value than the deterministic alternative it also performs well in terms of startup costs in the presence of river flow travel delay the practice based method is even more outperformed by the stochastic model

agent based analysis of the impact of the imbalance pricing mechanism on market behavior in electricity balancing markets abstract the imbalance pricing mechanism is an important design variable within european type electricity balancing markets that determines the incentives given to so called balance responsible parties brps to balance their electricity production and consumption portfolio to analyze the impact of alternative imbalance pricing mechanisms on balancing market performance an agent based model has been built in which the brps are the agents that decide autonomously in each round on their balancing strategy based on results in past rounds six alternative mechanisms are analyzed it is concluded that aiming for a small long position is generally the preferable brp strategy different imbalance pricing mechanisms lead to comparable system imbalances but single pricing results in the lowest imbalance costs for the brps and for the market as a whole

optimal alliance strategies among retailers under energy deviation settlement mechanism in china s forward electricity market an energy deviation settlement eds mechanism has been proposed to settle the deviation between consumption and energy contracts in china s forward electricity market due to high eds costs of electricity retailers a deviation mutual insurance dmi mechanism is put forward representing an option for electricity retailers to reduce the deviation through contract transfer given this background an optimal alliance strategy is proposed to maximize the utility of different types of individual electricity retailers the alliance income model considers the eds cost reduction and the cooperation cost analyzed based on transaction cost theory tct an improved income allocation method which considers distribution indexes selected by game theory and resource dependence theory rdt is proposed to ensure the comprehensive and reasonable allocation of alliance income considering the expected income and financial risk an evaluation model using conditional value at risk cvar as the financial risk assessment indicator is presented to measure the stability of alliances simulations based on data from a provincial electricity market in china illustrate that the eds costs of retailers can be reduced by selecting appropriate partners for alliance in addition the proposed alliance income allocation method is more reasonable and more targeted than the cooperative game based methods

strategic offering for a wind power producer as a result of subsidies and technological maturity renewable electricity producers have grown in some jurisdictions to clearly dominant positions in the market under this context we propose an offering strategy for a wind power producer with market power that participates in the day ahead market as a price maker and in the balancing market as a deviator uncertainty pertaining to wind power production and balancing market price is represented through a set of correlated scenarios the proposed model is a stochastic mathematical program with equilibrium constraints mpec that can be recast as a tractable mixed integer linear programming milp problem which is solvable using available optimization software results from an illustrative example and two case studies show the effectiveness of the proposed model

risk assessment of virtual power plants offering in energy and reserve markets distributed energy resources ders can be integrated into a single entity namely virtual power plant vpp the integration enables them to participate in competitive wholesale electricity markets according to the different types of uncertainty faced by different ders this integration can also act as a risk hedging mechanism providing a surplus profit in this paper using a two stage stochastic programming approach risk averse optimal offering model for a vpp trading in a joint market of energy and spinning reserve service is presented the conditional value at risk cvar is used to control the risk of profit variability uncertainties involved in generation of renewables consumption of loads calls for reserve service as well as prices in the day ahead market the spinning reserve market rm and the balancing real time market bm are taken into consideration this paper assesses how total and surplus profits of vpp are affected by risk aversion participation in the rm and the pricing system in the bm for this purpose the role of the integration and the trends of energy and reserve transactions under both single and dual pricing systems in the bm are addressed in detail through a numerical study

gender wage differentials and discrimination in the new south africa research into discrimination within south africa sa has focused on racial issues with gender issues being largely ignored this study aims to estimate gender wage differentials and through decomposition analysis understand the different problems faced by white black coloured and indian asian in 1995 it is found that white and asian females suffer greater gender discrimination than their black and coloured counterparts which could be a signal to future problems black and coloured females may encounter the largest gender wage differential is faced by white females whilst the lowest is encountered by coloured and black females a possible explanation for this finding is the low subsistence wages that the black and coloured population groups command relative to other population groups

intraday trading of wind energy in this paper we tackle the problem of a wind power producer participating in a short term electricity market that allows for the continuous but potentially illiquid intraday trading of energy considering the realistic case of a wind farm operating in the western danish price area of nord pool we build a simple but effective algorithm for the wind power producer to fully benefit from the elbas intraday market we then investigate the sensitivity of the obtained benefits to the maximum volume of energy the wind power producer is willing to trade in the intraday market the ultimate aim of the trade either to decrease energy imbalances or to increase profits and to the installed capacity of the wind farm our numerical results reveal that the wind power producer can substantially increase his revenues by partaking in the intraday market but with diminishing returns to scale a result that we attribute to the low liquidity of elbas

trading wind generation in short term energy markets even with state of the art forecasting methods the short term generation of wind farms cannot be predicted with a high degree of accuracy in a market situation these forecasting errors lead to commercial risk through imbalance costs when advance contracting this situation is one that needs to be addressed due to the steady increase in the amount of grid connected wind generation combined with the rise of deregulated market orientated electricity systems in the presence of imbalance prices and uncertain generation a method is required to determine the optimum level of contract energy to be sold on the advance markets such a method is presented here using markov probabilities for a wind farm and demonstrates substantial reductions in the imbalance costs the effect of market closure delays and forecasting window lengths are also shown

offering strategy of wind power producer a multi stage risk constrained approach given the significant amount of installed generation capacity based on wind power and also due to current economic downturn the subsidies and incentives that have been widely used by wind power producers to recover their investment costs have decreased and are even expected to disappear in the near future in these conditions wind power producers need to develop offering strategies to make their investments profitable counting solely on the market this paper proposes a multi stage risk constrained stochastic complementarity model to derive the optimal offering strategy of a wind power producer that participates in both the day ahead and the balancing markets uncertainties concerning wind power productions market prices demands bids and rivals offers are efficiently modeled using a set of scenarios the conditional value at risk metric is used to model the profit risk associated with the offering decisions the proposed model is recast as a tractable mixed integer linear programming program solvable using available branch and cut algorithms results of a case study are reported and discussed to show the effectiveness and applicability of the proposed approach

demand response application by strategic wind power producers this paper considers a wind power producer playing strategically in a day ahead market while willing to set demand response dr contracts with a dr aggregator to this end a bilevel problem including a single leader and two followers is formulated the wind power producer is the leader aiming at maximizing its profit through offering into a day ahead market and clearing its deviation in a balancing market the strategic behavior of the producer in the day ahead market is modeled through the market clearing process follower 1 in addition the dr aggregator behavior is modeled through a revenue function in which the aggregator is able to sell its dr product to the wind power producer other competitors and the day ahead market follower 2 the overall problem is a stochastic mathematical program with equilibrium constraints mpec in which wind power production and imbalance prices are associated with uncertainty the problem is then transformed into a linear programming approach a case of the nordic market is chosen to assess the validity of the given problem

stochastic joint optimization of wind generation and pumped storage units in an electricity market one of the main characteristics of wind power is the inherent variability and unpredictability of the generation source even in the short term to cope with this drawback hydro pumped storage units have been proposed in the literature as a good complement to wind generation due to their ability to manage positive and negative energy imbalances over time this paper investigates the combined optimization of a wind farm and a pumped storage facility from the point of view of a generation company in a market environment the optimization model is formulated as a two stage stochastic programming problem with two random parameters market prices and wind generation the optimal bids for the day ahead spot market are the ldquohere and nowrdquo decisions while the optimal operation of the facilities are the recourse variables a joint configuration is modeled and compared with an uncoordinated operation a realistic example case is presented where the developed models are tested with satisfactory results

rent seekers who demand government production bureaucratic output and the price of complements many goods and services produced by government bureaus are sold at prices which do not maximize net revenues maximize profits or minimize losses indeed bureaucratic institutions typically create incentives to expand production beyond that which would maximize net revenues furthermore many of the products sold by government bureaus are highly complementary to privately produced goods and services if a bureau s output is not priced to maximize net revenues then private sellers of various complements may be in a position to extract rents by adjusting their prices this paper explores the implications of bureaucratically generated rents for privately produced complements first rent seeking can materialize when private sector interests apply pressure for expanded bureau production and lower bureau prices second if the bureau does expand its production capacity beyond the net revenue maximizing level and if a private producer obtains exclusive rights to supply complements then the extraction of rents will result in an inefficient mix of resources in bureaucratic production the basis of the inefficiency is not the reason often given however rather inefficiencies arise because the actual level of use is less than that which the bureaucratic plant was constructed to produce due to the relatively high price of the complementary services

bringing wind energy to market wind energy is a rapidly growing source of renewable energy generation however the current extra market approach to its assimilation into the electric grid will not scale at deep penetration levels in this paper we investigate how an independent wind power producer might optimally offer its variable power into a competitive electricity market for energy starting with a stochastic model for wind power production and a model for a perfectly competitive two settlement market we derive explicit formulae for optimal contract offerings and the corresponding optimal expected profit as wind is an inherently variable source of energy we explore the sensitivity of optimal expected profit to uncertainty in the underlying wind process we also examine the role of forecast information and recourse markets in this setting we quantify the role of reserves in increasing reliability of offered contracts and obtain analytical expressions for marginal profits resulting from investments in improved forecasting and local auxiliary generation the formulae make explicit the relationship between price signals and the value of such firming strategies

explaining personality pay gaps in the uk using the british household panel survey we estimate the effect on pay of each of the big five personality traits for employed men living in the uk we add to the existing literature by estimating the role of factors such as education and occupation in explaining personality pay gaps by allowing the personality traits to affect wage differently across occupations education levels and other workers characteristics and by investigating personality pay gaps for high and low paid workers we find that openness to experience is the most relevant personality trait in explaining wages followed by neuroticism agreeableness extroversion and conscientiousness openness and extroversion are rewarded while agreeableness and neuroticism are penalized but the openness pay gap is totally explained by differences in worker characteristics particularly education and occupation

a meta analysis of the international gender wage gap abstract since the early 1970s a number of authors have calculated gender wage differentials between women and men of equal productivity this meta study provides a new quantitative review of this vast amount of empirical literature on gender wage differentials as it concerns not only differences in methodology data and time periods but also different countries we place particular emphasis on a proper consideration of the quality of the underlying study which is done by a weighting with quality indicators the results show that data restrictions i e the limitation of the analysis to new entrants never marrieds or one narrow occupation only have the biggest impact on the resulting gender wage gap moreover we are able to show what effect a misspecification of the underlying wage equation like the frequent use of potential experience has on the calculated gender wage gap over time raw wage differentials worldwide have fallen substantially however most of this decrease is due to better labor market endowments of females

minimization of imbalance cost trading wind power on the short term power market present power markets are designed for trading conventional generation for wind generation to participate in a short term energy market lengthy wind power production forecasts are required although wind speed forecasting techniques are constantly improving wind speed forecasts are never perfect and resulting wind power forecast errors imply imbalance costs for wind farm owners in this paper a new method for minimization of imbalance costs is developed stochastic programming is used to generate optimal wind power production bids for a short term power market a wind power forecast error is represented as a stochastic process the imbalance costs resulting from this strategy are then compared to the case when wind power production bids on a short term power market are based directly on a wind speed forecast

gender role attitudes and the labour market outcomes of women across oecd countries this paper uses data from the world value surveys 1990 1995 1999 to investigate the impact of gender role attitudes and work values on women s labour market outcomes across 25 oecd countries anti egalitarian views are found to display the strongest negative association with female employment rates and the gender pay gap these views are however softening among recent cohorts on the other hand perceptions of women s role as homemakers which are likely formed in youth and linked to religious ideology are more persistent over time they could be implicated in the recent slowdown of the gender convergence in pay finally the unavoidable clash between family values and egalitarian views that takes the form of an inner conflict for many women the so called mother s guilt is another obstacle in the path towards greater gender equality in the labour market copyright 2005 oxford university press

the impact of wind generation on wholesale electricity prices in the hydro rich pacific northwest extant literature documents that wind generation can reduce wholesale electricity market prices by displacing conventional generation but how large is the wholesale price effect of wind generation in an electricity market dominated by hydroelectric generation we explore this question by analyzing the impact of wind generation on wholesale electricity prices in the pacific northwest region of the united states this hydro rich system tends to be energy limited rather than capacity constrained with its marginal generation during the hydro runoff season often a hydro unit instead of a natural gas fired unit we find that increased wind generation reduces wholesale market prices by a small but statistically significant amount while a hydro rich system can integrate wind generation at a lower cost than a thermal dominated region the direct economic benefits to end users from greater investment in wind power may be negligible

the impact of psychological and human capital on wages historically economists have taken the position that psychological capital is either unobservable or immeasurable thus heretofore little evidence has been available on the contribution of psychological capital to wages using data drawn from two different waves of the national longitudinal survey of youth we offer evidence that psychological capital has both a direct effect via self esteem and an indirect effect through locus of control on an individual s real wage we find a person s wage is more sensitive to changes in self esteem than to comparable alterations in human capital both relative wages and human capital contribute to self esteem

short term load forecasting methods an evaluation based on european data this paper uses intraday electricity demand data from ten european countries as the basis of an empirical comparison of univariate methods for prediction up to a day ahead a notable feature of the time series is the presence of both an in traweek and an intraday seasonal cycle the forecasting methods considered in the study include arima modeling periodic ar modeling an extension for double seasonality of holt winters exponential smoothing a recently proposed alternative exponential smoothing formulation and a method based on the principal component analysis pca of the daily demand profiles our results show a similar ranking of methods across the 10 load series the results were disappointing for the new alternative exponential smoothing method and for the periodic ar model the arima and pca methods performed well but the method that consistently performed the best was the double seasonal holt winters exponential smoothing method

on the market impact of wind energy forecasts this paper presents an analysis of how day ahead electricity spot prices are affected by day ahead wind power forecasts demonstration of this relationship is given as a test case for the western danish price area of the nord pool s elspot market impact on the average price behaviour is investigated as well as that on the distributional properties of the price by using a non parametric regression model to assess the effects of wind power forecasts on the average behaviour the non linearities and time variations in the relationship are captured well and the effects are shown to be quite substantial furthermore by evaluating the distributional properties of the spot prices under different scenarios the impact of the wind power forecasts on the price distribution is proved to be considerable the conditional price distribution is moreover shown to be non gaussian this implies that forecasting models for electricity spot prices for which parameters are estimated by a least squares techniques will not have gaussian residuals hence the widespread assumption of gaussian residuals from electricity spot price models is shown to be inadequate for these model types the revealed effects are likely to be observable and qualitatively similar in other day ahead electricity markets significantly penetrated by wind power

panel estimates of the earnings gap in norway do female immigrants experience a double earnings penalty this study explores the possibility that being both a female and an immigrant will impose an earnings disadvantage on immigrant women in norway well known techniques are used to decompose the earnings gap between norwegian men and immigrant women into portions attributable to productivity differentials portions attributable to a gender effect and portions attributable to an ethnic effect the analysis supports the following conclusions first there is evidence of a double negative effect on female immigrant earnings second gender effect is more important than ethnic effect finally the discrimination estimates are robust to the alternative methods used in decomposing norwegian men immigrant women earnings gap

the impact of intraday markets on the market value of flexibility decomposing effects on profile and the imbalance costs abstract an increasing share of variable renewable energy sources vres basically affects the electricity price formation in two ways 1 the so called merit order effect tends to lower the base price level and challenges conventional plants to remain profitable 2 due to the variable nature of renewable energy infeed the short term demand for flexibility increases and changes the volatility of electricity prices the more variable prices offer opportunities for controllable electricity producers ceps who provide up and down ramping flexibility to increase their revenues in contrast the vres with high degrees of simultaneity tend to pay for this flexibility in the electricity spot market to reduce their imbalance exposure the intraday market idm for electricity has gained importance for the market value of different technologies lately and continues to expand due to the increasing efforts to balance within day deviation from day ahead schedules this article presents a combination and extension of two existing models to capture the peculiarities of the intraday price formation and to analyze the impact of the idm on the market value of vres and ceps doing so the paper suggests an adjustment of the classical market value factor metric and to go beyond classical day ahead market dam information the article shows that market value factors mvfs can be stabilized if the idm delivers market based price signals for the costs of flexibility that are sufficient to activate flexibilities prior to the usually more expensive imbalance mechanism ibm yet the mvfs from single vre technologies will worsen if their market share is high enough to outweigh forecast errors from other technologies and if they become a permanent price maker in the idm and the ibm

optimal bidding of a group of wind farms in day ahead markets through an external agent in deregulated electricity markets producers offer their energy to the day ahead market as the subsidies for renewable producers are becoming lower and lower they have to adapt to market prices this paper models the energy trading in the day ahead market for wind power producers different strategies are proposed for this purpose 1 several wind farms offering their energy separately to the day ahead market 2 the same strategy as in 1 but compensating the imbalance among different wind farms and 3 a joint offer involving several wind farms through an external agent in order to minimize the imbalances between the offer and the final power generation the strategies are modeled with stochastic mixed integer linear programming and conditional value at risk is used to consider the risk assessment the expected profit including risk aversion is maximized for each wind power producer and for the set of wind power producers in the case of a joint offer a comparison of the different cases is described in detail in a case study and relevant conclusions are provided

impact of renewables on electricity markets do support schemes matter abstract rising renewable shares influence electricity markets in several ways among others average market prices are reduced and price volatility increases therefore the missing money problem in energy only electricity markets is more likely to occur in systems with high renewable shares nevertheless renewables are supported in many countries due to their expected benefits the kind of support instrument can however influence the degree to which renewables influence the market while fixed feed in tariffs lead to higher market impacts more market oriented support schemes such as market premiums quota systems and capacity based payments decrease the extent to which markets are affected this paper analyzes the market impacts of different support schemes for this purpose a new module is added to an existing bottom up simulation model of the electricity market in addition different degrees of flexibility in the electricity system are considered a case study for germany is used to derive policy recommendations regarding the choice of support scheme

appropriable rents from yellowstone park a case of incomplete contracting i introduction though the general populace accepts that national parks are and should be the domain of government the history of our first national park yellowstone reveals that from the beginning private entrepreneurs were actively involved in preserving the amenity values and capturing the amenity rents to appropriate the rents from yellowstone the early entrepreneurs had to carve the amenity values from the common domain or see them dissipated through open access without private ownership of the land this was accomplished through vertical integration of complementary inputs namely transportation services and tourist facilities necessary for the enjoyment of the natural amenities the extent of private sector success or failure in the history of yellowstone can be best understood in the context of the theory of the firm as developed by armen alchian his work with demsetz 1972 and with klein and crawford 1978 expands our understanding of how firms contract to appropriate rents and prevent postcontractual opportunism klein crawford and alchian 1978 300 distinguish between two reasons for vertical integration both of which apply to private firms operating in yellowstone at the time of its creation the first is the successive monopoly problem which occurs when two monopolists supply inputs into a final product or service and the second is postcontractual opportunism our purpose here is to apply these two important threads from the firm s contractual tapestry to the formation and operation of yellowstone national park the central theme is that amenity rents associated with the yellowstone region either could be dissipated through open access and the ensuing tragedy of the commons or appropriated through contractual arrangements that limited entry to the commons the former occurred until the northern pacific railroad with its monopoly on transportation services vertically integrated with monopoly suppliers of tourist facilities and operated the park as if it were privately owned 1 however the potential for rent dissipation still existed because the railroad did not own the park itself and could not effectively contract with the federal government to restrict entry therefore when the federal government opened the park to automobiles in 1915 the railroad s monopoly was eliminated and rent dissipation occurred through congestion ii brief history of yellowstone the natural features of the area that is now yellowstone national park were well known by 1860 following john colter s exploration of the area in 1807 numerous other trappers and later prospectors explored colter s hell in 1865 1870 and 1871 the first formal explorers financed in part by congress were sent to yellowstone these explorers provided scientific information photographs and paintings that increased the awareness in the east about the yellowstone area this awareness culminated in the creation of yellowstone national park by an act of congress on 1 march 1872 making it the first national park though yosemite had been established as a state preserve in 1864 early administration of the park was haphazard because the federal government provided no funds for operating expenses indeed many of yellowstone s natural features were being defaced until in 1886 the u s army assumed administrative responsibilities stationing a cavalry troop there the army stayed until 1918 at the time of yellowstone s creation the region was relatively inaccessible and sparsely settled but railroads changed this the northern pacific railroad completed its transcontinental line in 1883 and immediately added a sixty mile spur from livingston montana to yellowstone s northern entrance in 1903 the chicago burlington and quincy railroad gained access to yellowstone through cody wyoming and in 1908 the union pacific arrived at west yellowstone montana finally in 1915 the park was opened to automobile traffic

medium term multimarket optimization for virtual power plants a stochastic based decision environment this paper presents a decision making tool tailored for a portfolio manager aiming at maximizing its profit by participating in both energy and balancing services markets the proposed formulation is modular and flexible so as to comply with any portfolio configuration and to follow evolutions of the market regulation policy detailed formulations of both medium term i e typically from one week up to one year ahead and short term i e day ahead perspectives are jointly considered and solved using surrogate based optimization the objective is to adequately account for the interdependencies and possible conflicting objectives between these time horizons then in order to overcome the resulting computational burden associated with the different sources of uncertainty an innovative method for generating time and space dependent scenarios is developed the approach is based on nonparametric copulas and in contrast to traditional methods allows including a large number of uncertain parameters into the formulation finally the procedure is tested and illustrated for a portfolio manager with diversified assets the case study is developed to emphasize the advantages of the proposed optimization tool in terms of accuracy and computational burden of the proposed models as well as subsequent generated profit

bidding strategy of virtual power plant for participating in energy and spinning reserve markets part i problem formulation this paper addresses the bidding problem faced by a virtual power plant vpp in a joint market of energy and spinning reserve service the proposed bidding strategy is a non equilibrium model based on the deterministic price based unit commitment pbuc which takes the supply demand balancing constraint and security constraints of vpp itself into account the presented model creates a single operating profile from a composite of the parameters characterizing each distributed energy resources der which is a component of vpp and incorporates network constraints into its description of the capabilities of the portfolio the presented model is a nonlinear mixed integer programming with inter temporal constraints and solved by genetic algorithm ga

wind power offering strategy in day ahead markets employing demand response in a two stage plan this paper deals with wind power offering strategies in day ahead markets a new plan is proposed in which a wind power producer participates in the day ahead market while employing demand response dr to smooth its power variations in this context a new dr scheme is presented through which the wind power producer is able to achieve dr by establishing various dr agreements with dr aggregators the proposed offering plan involves two stages the first stage clears on the day ahead market the wind power producer decides on day ahead offers as well as dr agreements with the aggregator the second stage takes place on the balancing market in a successive approach the wind power producer determines its energy trading for each period until the whole day is covered additionally proper dr agreements for each period are confirmed here the proposed plan is formulated in a stochastic programming approach where its validity is assessed on a case of the nordic market

maximizing profit of a wind genco considering geographical diversity of wind farms uncertainty and geographical diversity of wind speeds create risk for a wind power generation company wgenco to make the maximum profit from power market trading a probabilistic approach is proposed to estimate the profit of a wgenco considering geographical diversity and uncertainty of wind speeds and market prices the objective of the optimization problem is to assist a wgenco to do the optimal bidding in market trading in order to make the maximum profit under various market and wind speed uncertainties the point estimate method pem has been improved to facilitate stochastic modeling of the aggregated power output of wind turbine generators in different locations in the problem formulation the principal component analysis pca is used to manage correlated wind speeds

nodal pricing for distribution networks efficient pricing for efficiency enhancing dg as distributed generation dg becomes more widely deployed distribution networks become more active and take on many of the same characteristics as transmission we propose the use of nodal pricing that is often used in the pricing of short term operations in transmission as an economically efficient mechanism nodal pricing would properly reward dg for reducing line losses through increased revenues at nodal prices and signal prospective dg where it ought to connect with the distribution network applying nodal pricing to a model distribution network we show significant price differences between buses reflecting high marginal losses moreover we show the contribution of a dg resource located at the end of the network to significant reductions in losses and line loading we also show the dg resource has significantly greater revenue under nodal pricing reflecting its contribution to reduced line losses and loading

economic assessment of the participation of wind generation in the secondary regulation market the aim of this paper is to analyze the profitability of wind technology as a potential participant in the frequency regulation specifically in the secondary regulation market the study is conducted for the spanish system using existing market rules however although this system has some peculiarities the main methodology could be applied in other systems firstly a bibliographical review of the relevant technical possibilities of this technology is carried out then a simulation study based on real data is conducted in order to evaluate the maximum possible incomes later a specific offer strategy is proposed and the income is estimated based on statistical modeling and checked by simulating its performance using the actual and forecasted productions of a wind portfolio it is concluded that under the current generation structure and regulatory framework in the spanish system the incomes obtained from the participation of wind technology would be modest however secondary regulation by wind generators might facilitate higher penetration levels of this technology in the long term with expected wind generation subsidies much reduced a greater need for regulation reserves and a possible increase in regulation prices regulation related incomes might become a sizeable fraction of the total income of wind generators

pricing energy and ancillary services in integrated market systems by an optimal power flow a detailed ac opf based formulation for procuring pricing and settling energy and ancillary service in simultaneous auctions by integrated market systems is presented the paper provides clear definitions of locational marginal prices for energy and ancillary service marginal prices in terms of lagrange multipliers the characteristics of the prices are analyzed especially when economic substitution among ancillary services is required the paper also evaluates the conditions under which opportunity costs are incurred to units that provide ancillary services it is particularly shown that the intuitive belief that the provision of regulation down service does not incur opportunity cost to the provider in general is not true

trading wind generation from short term probabilistic forecasts of wind power due to the fluctuating nature of the wind resource a wind power producer participating in a liberalized electricity market is subject to penalties related to regulation costs accurate forecasts of wind generation are therefore paramount for reducing such penalties and thus maximizing revenue despite the fact that increasing accuracy in spot forecasts may reduce penalties this paper shows that if such forecasts are accompanied with information on their uncertainty i e in the form of predictive distributions then this can be the basis for defining advanced strategies for market participation such strategies permit to further increase revenues and thus enhance competitiveness of wind generation compared to other forms of dispatchable generation this paper formulates a general methodology for deriving optimal bidding strategies based on probabilistic forecasts of wind generation as well as on modeling of the sensitivity a wind power producer may have to regulation costs the benefits resulting from the application of these strategies are clearly demonstrated on the test case of the participation of a multi mw wind farm in the dutch electricity market over a year

optimal offering and operating strategy for a large wind storage system as a price maker wind farms and energy storage systems are playing increasingly more important roles in power systems which makes their offering nonnegligible in some markets from the perspective of wind farm energy storage systems wf ess this paper proposes an integrated strategy of day ahead offering and real time operation policies to maximize their overall profit as participants with large capacity in electricity markets can influence cleared prices by strategic offering a large scaled wf ess is assumed to be a price maker in day ahead markets correspondingly the strategy considers influence of offering quantity on cleared day ahead prices and adopts linear decision rules as the real time control strategy these allow enhancing overall profits from both day ahead and balancing markets the integrated price maker strategy is formulated as a stochastic programming problem where uncertainty of wind power generation and balancing prices are taken into account in the form of scenario sets permitting to reformulate the optimization problem as a linear program case studies validate the effectiveness of the proposed strategy by highlighting and quantifying benefits comparing with the price taker strategy and also show the profit enhancement brought to the distributed resources

the german paradox in the balancing power markets abstract this paper provides answers to questions raised by hirth and ziegenhagen 1 regarding the german paradox in the balancing power markets we show that in spite of the increasing energy production from variable renewable energy sources there is no need for a higher demand of balancing power in germany because adaptations in the energy market design were undertaken and grid control cooperations led to immense efficiency savings additionally we investigate the price developments in the german secondary balancing power market we find evidence that the suppliers coordinate on a price level which is far above the competitive level and that they orientate their power bids towards previous auction prices

causes of the eu ets price drop recession cdm renewable policies or a bit of everything new evidence the price of eu allowances euas in the eu emissions trading scheme eu ets fell from almost 30 tco2 in mid 2008 to less than 5 tco2 in mid 2013 the sharp and persistent price decline has sparked intense debates both in academia and among policy makers about the decisive allowance price drivers in this paper we examine whether and to what extent the eua price drop can be justified by three commonly identified explanatory factors the economic recession renewable policies and the use of international credits capitalizing on marginal abatement cost theory and a broadly extended data set we find that only variations in economic activity and the growth of wind and solar electricity production are robustly explaining eua price dynamics contrary to simulation based analyses our results point to moderate interaction effects between the overlapping eu ets and renewable policies the bottom line however is that 90 of the variations of eua price changes remains unexplained by the abatement related fundamentals together our findings do not support the widely held view that negative demand shocks are the main cause of the weak carbon price signal in view of the new evidence we evaluate the eu ets reform options which are currently discussed

a review of the value of aggregators in electricity systems abstract distributed energy resources ders are being adopted throughout the world aggregators are lauded by some as critical in enabling ders to provide these valuable electricity services at scale in this light regulatory and policy bodies are discussing the role of aggregators and even the need to support their market entry in order to shed light on the economically efficient regulation of aggregators in electricity systems this paper systematically assesses the economic fundamentals of aggregators we perform a critical review of the value of aggregators defining the factors that determine their role in power systems under different technological and regulatory scenarios we identify three categories of value that aggregators may create fundamental transitory and opportunistic fundamental value is intrinsic to aggregation and is independent of the market or regulatory context transitory value can be significant in the near term but may be diminished by technological or regulatory advances finally opportunistic value emerges as a result of regulatory or market design flaws and may endanger the economic efficiency of the power system this paper provides a template for regulators to encourage the efficient development of aggregators while eliminating the potential for economic inefficiencies through opportunistic aggregation

is the gender wage gap declining in the netherlands in this paper i try to answer the question whether the gender wage gap in the netherlands is declining i posed this question because on several other indicators labour market differences between men and women in the netherlands declined or disappeared altogether first of all the labour market participation of women has increased and women on the labour market are no longer a small minority second the difference in productive characteristics between men and women is disappearing third both product and labour markets have become increasingly competitive due to changes in regulation like anti trust laws which should have an effect on the gender wage gap contrary to these expectations i did not find a declining gender wage gap the data in dutch institute for labour studies osa labour supply panel show a steady gender gap of approximately nineteen per cent at most twenty five to thirty per cent of the gap can be explained by productivity differences the largest part of the gender wage gap is due

balancing power and variable renewables three links abstract balancing power is used to quickly restore the supply demand balance in power systems the need for this tends to be increased by the use of variable renewable energy sources vre such as wind and solar power this paper reviews three channels through which vre and balancing systems interact the impact of vre forecast errors on balancing reserve requirements the supply of balancing services by vre generators and the incentives to improve forecasting provided by imbalance charges the paper reviews the literature provides stylized facts from german market data and suggests policy options surprisingly while german wind and solar capacity has tripled since 2008 balancing reserves have been reduced by 15 and costs by 50

pros and cons of exposing renewables to electricity market risks a comparison of the market integration approaches in germany spain and the uk abstract the article examines how renewable electricity res e producers are integrated into the electricity market under the support legislations and regulatory frameworks of germany spain and the uk focus is on wind power which faces the highest market integration challenge of all res e the analysis shows that the three countries follow contrasting approaches of exposing res e producers to the market risks of forward electricity markets balancing markets and system planning requirements risk exposure is highest in the uk and lowest in germany from a policy maker s perspective there is a trade off between a high risk and a low risk approach when res e face high market risks a higher level of financial support is required to stimulate res e development than in a low risk environment but the exposure to market risks may also give an incentive to make efficient use of the respective market thus limiting the indirect costs to society the special characteristics of wind energy however put natural limits to the response of wind power plants to market prices and locational price signals and will increasingly influence electricity markets and grid infrastructure these interdependencies should be recognised in the design of res e policies and market regulations

the merit order effect a detailed analysis of the price effect of renewable electricity generation on spot market prices in germany the german feed in support of electricity generation from renewable energy sources has led to high growth rates of the supported technologies critics state that the costs for consumers are too high an important aspect to be considered in the discussion is the price effect created by renewable electricity generation this paper seeks to analyse the impact of privileged renewable electricity generation on the electricity market in germany the central aspect to be analysed is the impact of renewable electricity generation on spot market prices the results generated by an agent based simulation platform indicate that the financial volume of the price reduction is considerable in the short run this gives rise to a distributional effect which creates savings for the demand side by reducing generator profits in the case of the year 2006 the volume of the merit order effect exceeds the volume of the net support payments for renewable electricity generation which have to be paid by consumers

gender roles and human capital inverstment the relationship between traditional attitudes and female labour market performance this paper investigates the relationship between the labour market behaviour of females and their attitudes towards traditional gender roles an attitudes index is constructed by employing individuals responses to statements related to the role of women and examined to determine whether it is correlated with individual characteristics the paper examines whether these attitudes influence human capital attainment and whether they are weakly exogenous to educational attainment it also focuses on the impact of these traditio nal attitudes upon labour supply and the return to education the results are dramatic it is found that females attitudes towards working women are developed in their youth and result in substantial reductions in their human capital investment labour supply and rates of return to education furthermore it is found that these attitudes are determined outside the educational process

the feasibility of hydrogen storage for mixed wind nuclear power plants a novel methodology for economic evaluation of hydrogen storage for a mixed wind nuclear power plant is presented in this article in a context of a ldquohydrogen economyrdquo the simulation of the operation of the combined nuclear wind hydrogen system is discussed first where the selling and buying of electricity and the selling of excess hydrogen and oxygen is optimized to maximize profits this simulation is done in two phases in the pre dispatch phase the system operation is optimized according to stochastic wind and price forecasts to obtain optimal hydrogen charge levels for the operational horizon in the second phase a real time dispatch is carried out on an hourly basis to optimize the operation of the system to maximize profits and to follow the storage levels of the pre dispatch phase based on the operation planning and dispatch results an economic evaluation is performed to determine the feasibility of the proposed scheme for investment purposes the results of these studies demonstrate that hydrogen for the sole purpose of storage of electricity is not economically feasible at the current state of hydrogen technology development unless hydrogen is sold to the market for other purposes such as transportation as in the case in a hydrogen economy or in the case of limited electricity transmission capacities i e transmission congestion

the impact of european balancing rules on wind power economics and on short term bidding strategies abstract wind power represents a significant percentage of the european generation mix and this will increase to fulfill the renewable energy targets different balancing rules are applied to wind power among the countries for instance to what extent wind power producers wpps are responsible for the energy imbalances and how those imbalances are penalized this paper discusses those different rules and evaluates their effects on wpp bidding strategies to do so a quantitative analysis is presented for an offshore wind farm considering the differences in the balancing rules and prices of belgium denmark germany and the netherlands the quantitative approach consists of a stochastic optimization model that maximizes the profits of a wpp by trading in different markets day ahead and intraday and computes the final energy delivered the model considers uncertainties of most important parameters such as wind energy forecasts and prices at different time frames the results show that the imbalance pricing design and the allocation of balance responsibility significantly affect wpp revenues additionally wpps deviate differently from the expected energy depending on the balancing rules which can impact the system furthermore these balancing rules should be considered with other market regulations such as the design of support schemes

the structure of a contract and the theory of a non exclusive resource the process of arriving at a useful concept of analysis is not only slow and painful but also may go astray and attain nothing useful someone begins with one example or observation followed by a theory which is intuitively plausible a theoretical term associated with a vague concept is coined examples of a seemingly different type emerge which call for another theory the process goes on as examples and theories continue to accumulate the different categories under the same heading of analysis serve only to confuse and each associated theory becomes ad hoc such has been the fate of the concept of externality a more useful approach i think is via contractual conditions the example chosen for illustration is marine fisheries where the fishing right is taken

opportunity cost bidding by wind generators in forward markets analytical results wind generation must trade in forward electricity markets based on imperfect forecasts of its output and real time prices when the real time price differs for generators that are short and long the optimal forward strategy must be based on the opportunity costs of charges and payments in real time rather than a central estimate of wind output we present analytical results for wind s optimal forward strategy in the risk neutral case the optimal strategy is determined by the distribution of real time available wind capacity and the expected real time prices conditioned on the forward price and wind out turn our approach is simpler and more computationally efficient than formulations requiring specification of full joint distributions or a large set of scenarios informative closed form examples are derived for particular specifications of the wind price dependence structure in the usual case of uncertain forward prices the optimal bidding strategy generally consists of a bid curve for wind power rather than a fixed quantity bid a discussion of the risk averse problem is also provided an analytical result is available for aversion to production volume risk however we doubt whether wind owners should be risk averse with respect to the income from a single settlement period given the large number of such periods in a year

identifying barriers to large scale integration of variable renewable electricity into the electricity market a literature review of market design abstract for reaching the 2 c climate target the robust growth of electricity generation from variable renewable energy sources vre in the power sector is expected to continue accommodation of the power system to the variable uncertain and locational dependent outputs of vre causes integration costs integrating vre into a well functioning electricity market can minimize integration costs and drive investments in vre and complementary flexible resources however the electricity market in the european union eu as currently designed seems incapable to deliver this end this paper aims to provide a comprehensive literature review of barriers to the large scale market integration of vre in the eu electricity market design based on the set up of the eu electricity market a framework was developed to incorporate the most pertinent market integration barriers and resulting market inefficiencies this paper concludes that an overhaul is needed for the current eu electricity market to address all barriers identified firstly a discrete auction intraday market a marginal pricing balancing market a two price imbalance settlement and a nodal pricing locational marginal pricing mechanism seem more promising in limiting integration costs secondly to support business cases of vre and complementary flexible resources in the electricity market a level playing field should be established and the price cap should be lifted up to the value of lost load voll meanwhile to fit vre s market participation a higher time resolution of trading products and later gate closure time in different submarkets would be required lastly feed in support schemes currently widely used for vre investments might be inconsistent with market integration as they increase integration costs and lock vre investments in a subsidy dependent pathway to avoid such lock in further investigation of alternative capacity based support schemes is recommended

employers discriminatory behavior and the estimation of wage discrimination this paper considers the linkage of empirical estimates of wage discrimination between two groups introduced by oaxaca 1973 to a theoretical model of employers discriminatory behavior it is shown that conditional on different assumptions about employers discriminatory tastes oaxaca s estimators of wage discrimination can be derived that the approach is more generally useful is demonstrated by deriving an alternative estimator of wage discrimination based on the assumption that within each type of labor e g unskilled skilled the utility function capturing employers discriminatory tastes is homogeneous of degree zero with respect to labor inputs from each of the two groups the estimators are compared empirically in an application to male female wage differentials

female labor force intermittency and current earnings a switching regression model with unknown sample selection using the health and retirement survey from the usa this paper finds a 16 selectivity corrected wage penalty among women who engage in intermittent labour market activity this penalty is experienced at a low level of intermittent activity but appears to not play an important role in a woman s decision to undertake such activity in addition employer preferences appear to play a larger role than human capital atrophy in the determination of the wage penalty

capital market response to emission rights returns evidence from the european power sector prior studies on the distributional effects of the european union s emission trading scheme eu ets have so far only relied on supply and demand data empirical evidence from capital markets has been missing we address this gap and measure the ets s economic consequences using the expectations of investors towards the regulatory impact on firm value employing a multifactor model we show that returns on common stock of the largest affected industry power generation are positively correlated with rising prices for emission rights this implies that the market predicts that firms are not only able to pass on their share of the regulatory burden to customers but even achieve windfall profits by overcompensating for the costs

personality and the gender wage gap in this study we investigate whether personality traits contribute towards a better understanding of the reasons for the gender wage gap we explore whether two of the personality factors put forward by bowles et al 2001 as likely to be incentive enhancing in the employer employee relationship can explain the difference in wages for women and men these are 1 personal self efficacy locus of control loc and 2 time preference we also study the role of the so called big five personality traits extraversion emotional stability agreeableness openness intellect and conscientiousness which have been associated with earnings in several recent studies using a sample of dutch employees we found that 11 5 of the observed gender wage gap could be ascribed to differences in the personality trait scores mainly in agreeableness and intellect while less than 0 5 could be ascribed to gender differences in the returns to the traits the addition of personality traits to a traditional human capital

the market value of variable renewables the effect of solar wind power variability on their relative price this paper provides a comprehensive discussion of the market value of variable renewable energy vre the inherent variability of wind speeds and solar radiation affects the price that vre generators receive on the market market value during windy and sunny times the additional electricity supply reduces the prices because the drop is larger with more installed capacity the market value of vre falls with higher penetration rate this study aims to develop a better understanding on how the market value with penetration and how policies and prices affect the market value quantitative evidence is derived from a review of published studies regression analysis of market data and the calibrated model of the european electricity market emma we find the value of wind power to fall from 110 of the average power price to 50 80 as wind penetration increases from zero to 30 of total electricity consumption for solar power similarly low value levels are reached already at 15 penetration hence competitive large scale renewable deployment will be more difficult to accomplish than as many anticipate

analysis of the imbalance price scheme in the spanish electricity market a wind power test case this work investigates the interaction between wind power and electricity markets the paper is focused on balancing markets pricing policies the proposal of a new imbalance price scheme is included and conveniently evaluated this proposed scheme tries to minimise the use of ancillary services to compensate for deviations in searching for a more efficient market design the effectiveness of imbalance prices as market signals is also examined and policy recommendations regarding imbalance services are discussed two test cases are included that analyse the participation of a wind power producer in the spanish electricity market using a stochastic optimisation strategy for this purpose the uncertainty of the variables is considered i e wind power production and prediction intraday and imbalance prices test cases were run with real data for 10 months and realistic results are presented along with a hypothetical test case the regulation of the imbalance prices may not be adequate for the spanish electricity market because an error drop is not sufficiently encouraged therefore we suggest the application of a new imbalance price scheme which includes an additional constraint the conclusions of this paper can be assumed to be general policy recommendations

pool strategy of a price maker wind power producer we consider the problem of a wind power producer trading energy in short term electricity markets the producer is a price taker in the day ahead market but a price maker in the balancing market and aims at optimizing its expected revenues from these market floors the problem is formulated as a mathematical program with equilibrium constraints mpec and cast as a mixed integer linear program milp which can be solved employing off the shelf optimization software the optimal bid is shown to deliver significantly improved performance compared to traditional bids such as the conditional mean or median forecast of wind power distribution finally sensitivity analyses are carried out to assess the impact on the offering strategy of the producer s penetration in the market of the correlation between wind power production and residual system deviation and of the shape of the forecast distribution of wind power production

do support systems for res e reduce eu ets driven electricity prices abstract support systems for electricity from renewable energy sources res e can reduce electricity prices which have also been influenced by a co2 emission trading scheme ets additional res e substitutes electricity from fossil fuels and thus co2 emissions are reduced the demand for emission reductions is lowered as a result the co2 price is also reduced consequently the wholesale price for electricity decreases however most res e support systems are financed via the electricity market which increases the retail electricity price an assessment for germany shows that retail electricity prices in the first trading period of the eu ets 2005 2007 are lowered by 2 6 euro mwh due to additional res e considering the complete eu the effect is substantially higher this paper describes the effect and the influence of different policy designs it develops an approach for assessing the effect and applies it for the case of germany and roughly estimates the effect for the eu

wind power bidding strategy in the short term electricity market abstract this paper presents an analytical trading electricity model for wind power producers wpps in the short term electricity market in the u s this model addresses four specific uncertainties real time rt wind power generation day ahead da locational marginal prices lmps rt lmps and deviation penalty rates the model is designed to find the optimal bidding strategy to maximize the expected revenue under these uncertainties in addition this paper shows that advanced forecasting techniques could be used with the proposed bidding strategy to help wpps trade energy in short term markets a case study is presented to illustrate the effectiveness of this proposed bidding strategy and advanced forecasting techniques using a set of real data taken from a wind farm in the pjm electricity market

optimal contract pricing of distributed generation in distribution networks this paper proposes a bilevel programming approach to determine the optimal contract price of dispatchable distributed generation dg units in distribution systems two different agents are considered in the model namely the distribution company disco and the owner of the dg the former seeks the minimization of the payments incurred in attending the forecasted demand while the latter seeks the maximization of his profit to meet the expected demand the disco has the option to purchase energy from any dg unit within its network and directly from the wholesale electricity market a traditional distribution utility model with no competition among dg units is considered the proposed model positions the dg owner in the outer optimization level and the disco in the inner one this last optimization problem is substituted by its karush kuhn tucker optimality conditions turning the bilevel programming problem into an equivalent single level nonlinear programming problem which is solved using commercially available software tests are performed in a modified ieee 34 bus distribution network

a novel policy for locational marginal price calculation in distribution systems based on loss reduction allocation using game theory in this paper a novel locational marginal price lmp policy for distribution system with significant penetration of distribution generation dg in competitive electricity market is presented this new lmp method is based on remunerating dg units for their participation in reduced amount of energy losses in distribution systems brought about by participation of all dg units in supplying demand also this method is combined with an iterative solution this approach provides an efficient tool for distribution companies discos to estimate the state of the system in the next step which other existing approaches of lmp fail to provide this system state estimation finally in order to expand lmp method and provide effective prediction method for discos to estimate the day ahead state of the system ann tool is employed to predict the market price and demand for the next 24 h this lmp prediction is a powerful operational tool for disco to exert its control over private dg units however prediction methods contain error therefore uncertainty modeling is implemented for modeling the effect of error in prediction on the lmp calculation for the next day

how emission certificate allocations distort fossil investments the german example despite political activities to foster a low carbon energy transition germany currently sees a considerable number of new coal power plants being added to its power mix there are several possible drivers for this dash for coal but it is widely accepted that windfall profits gained through free allocation of ets certificates play an important role yet the quantification of allocation related investment distortions has been limited to back of the envelope calculations and stylized models so far we close this gap with a numerical model integrating both germany s particular allocation rules and its specific power generation structure we find that technology specific new entrant provisions have substantially increased incentives to invest in hard coal plants red to natural gas at the time of the ets onset more precisely disproportionate windfall profits compared more than half the total capital costs of a hard coal plant moreover shorter periods of free allocations would not have turned investors favours towards the cleaner natural gas technology because of pre existing economic advantages for coal in contrast full auctioning of permits or a single best available technology benchmark would have made natural gas the predominant technology of choice

incentive enhancing preferences personality behavior and earnings suppose there is a principal agent relationship between employer and employee in which effort is not contractible but is elicited through employer incentive mechanisms we term preferences that allow the employer to elicit effort at lower cost incentive enhancing we analyze how such preferences affect earnings nd then provide evidence that one of the relevant behavioral traits efficacy as well as other psychological aspects of individuals are significant influences on earnings we conclude that measures of cognitive performance are not sufficient indicators of the effectiveness of schools in promoting student labor market success incentive enhancing preferences are irreducibly heterogeneous incentive enhancing preferences help explain the persistence of poverty over generations within families and unlike cognitive skills incentive enhancing traits need not be welfare increasing for their bearers

contracting problems and regulation the case of the fishery the inefficiencies of common property fisheries are of continuing concern to economists the early work by scott gordon 1954 and anthony scott 1955 outlined the problem and later studies by james crutchfield and giulio pontecorvo 1969 and frederick bell 1972 provided empirical estimates of the losses that result those studies were followed by the dynamic models of colin clark 1976 and james quirk and vernon smith 1970 of optimal harvest rates and the use of corrective taxes or quotas to achieve them but in spite of a large and growing literature and the persuasiveness of the outlined efficiency criteria most fisheries retain common property aspects with overcapitalization and excessive labor input why those conditions persist and the failure of the regulatory response to them are the issues addressed in this paper we examine a number of fisheries but focus on the texas shrimp industry which is one of the nation s most valuable fisheries for a single species and which shares the common property characteristics observed elsewhere it is considered overcapitalized and catch per unit of effort is falling 2 examination of the fishery reveals the many margins along which rent dissipation occurs and the nature of the regulations necessary for controlling fishing effort to avoid those losses the regulatory environment in texas is complicated by conflict within the fishery between inshore and offshore fishermen the latter assert that bay shrimping reduces the number of shrimp that successfully migrate to the gulf the inshore fishery is highlighted by another issue the recent resettlement of some 30 45 000 vietnamese refugees including many fishermen along the texas coast marine advisory service paul starr their entry has been met by hostility and violence from existing shrimpers who recognize that they are in an environment characterized by the absence of property rights bay shrimpers have lobbied the texas legislature for broad limits on new entrants yet ironically the sale of additional boats by individual shrimpers to the vietnamese has facilitated entry of the refugees into the fishery regulations in the texas shrimp and other fisheries are incomplete leaving many options for rent dissipation uncontrolled because of high contracting costs among fishermen and political factors that mold government actions contracting costs are high among heterogeneous fishermen who vary principally with regard to fishing skill 3 montana state university and texas a m university respectively we benefitted from comments by terry anderson raymond c battalio gardner brown oscar burt micha gisser wade griffin john r moroney anthony d scott peter temin and participants in workshops at texas a m university and the university of washington research assistance was provided by scott barnhart and phil mizzi funding was provided by sea grant texas a m university throughout this paper we use the terms common property and open access interchangeably here the terms describe a situation where no property rights group or individual exist s for the resource 2catch per unit of effort in the inshore texas gulf and federal gulf waters is presented for 1963 77 by w l griffin c g tydlacka and w e grant they show catch per unit of effort generally falling in inshore and offshore waters while catch per unit of effort fluctuates from year to year it falls from approximately 360 kg shrimp per unit of effort to 220 kg from 1963 to 1977 the common property nature of the fishery is reflected in the following statistics since 1975 the number of vessels has grown by 23 percent nelson swartz for fish houses the record of entry is similar between 1970 a d 1977 the number of firms grew from 259 to 287 though during that period many left the industry as others entered the number of fish houses was calculated from license data supplied by the texas parks and wildlife department the record of entry by fish houses suggests that monopsony as discussed by colin clark and gordon munro is absent in the fishery 3there may be minor differences in labor leisure choices and capital but our statistical evidence and discussions with fishermen indicate that catch variations are largely due to skill government regulations in the texas bays restrict capital and our empirical evidence shows boats to be relatively homogeneous

sibling gender and wage differences abstractfamily influences on economic performance are investigated in particular sibship sex composition is related to hourly wages using data from the national longitudinal survey of youth 1979 the wages of men are increasing in the proportion of siblings who are brothers but the wages of women are insensitive to sibling gender nonwage outcomes are generally unaffected contrasts by age structure and demographic group are also presented the analysis addresses econometric challenges like the endogeneity of fertility and selection into the workforce in addition mechanisms such as labour market interactions human capital investment and role model effects are documented a questionnaire on job search indicates a same gender bias in the use of brothers and sisters in obtaining employment developmental and psychological assessments suggest that brothers may be associated with worse childhood home environments and more traditional family attitudes among women the findings are policy relevant and cont

electricity market participation of wind farms the success story of the spanish pragmatism abstract in the last 10 years more than 15 gw of wind power asociacion empresarial eolica spanish wind energy association nota de prensa press release 17 de enero de 2008 http www aeeolica org doc np 080117 espana supera los 15000 mw eolicos pdf have been installed in spain of which more than 3 5 gw in 2007 furthermore plans are to reach 20 gw by 2010 and there are expectations of an installed capacity exceeding 40 gw by 2020 this article will present the innovative solutions for technical and economical integration that allow to reach such high level wind penetration objectives the system peaks at around 44 gw and is almost isolated it will be described how the regulation has evolved from a pure feed in tariff to a market premium option where technical and economic integration has been a priority today approximately 97 of installed wind capacity accesses the spanish wholesale electricity market market integration has been crucial sending the correct signals to participants to look for the optimum technical solutions technical improvements have come from both wind power producers fault ride through capabilities visibility and controllability of wind power power production forecasting reactive power control and the system operator specific control centre dedicated to renewable energy sources res new security analysis tools gaining technical confidence of wind capabilities

promoting the market and system integration of renewable energies through premium schemes a case study of the german market premium abstract with the share of renewable energies within the electricity sector rising improving their market and system integration is of increasing importance by offering plant operators a premium on top of the electricity market price premium schemes represent an option to increase the alignment of renewable electricity production with market signals and have been implemented by several eu member states this paper examines the case study of the german market premium scheme adopted in 2012 building on an evaluation of early experiences we discuss whether the market premium contributes to the aims of market and or system integration effectiveness and what potential efficiency gains and additional costs of administering integration are associated with it efficiency while exposing renewables to price risks is not the scheme s purpose it has successfully increased participation in direct marketing however risks of overcompensating producers for marketing and balancing costs are high and the benefits of gradually leading plant operators towards the market are questionable incentives for demand oriented production are established but they seem insufficient particularly in the case of intermittent renewable energy sources to conclude we provide an outlook on alternative designs of premium schemes and discuss whether they seem better suited for addressing the challenges ahead

wind power trading under uncertainty in lmp markets this paper presents a new model for optimal trading of wind power in day ahead da electricity markets under uncertainty in wind power and prices the model considers settlement mechanisms in markets with locational marginal prices lmps where wind power is not necessarily penalized from deviations between da schedule and real time rt dispatch we use kernel density estimation to produce a probabilistic wind power forecast whereas uncertainties in da and rt prices are assumed to be gaussian utility theory and conditional value at risk cvar are used to represent the risk preferences of the wind power producers the model is tested on real world data from a large scale wind farm in the united states optimal da bids are derived under different assumptions for risk preferences and deviation penalty schemes the results show that in the absence of a deviation penalty the optimal bidding strategy is largely driven by price expectations a deviation penalty brings the bid closer to the expected wind power forecast furthermore the results illustrate that the proposed model can effectively control the trade off between risk and return for wind power producers operating in volatile electricity markets

marital status in a developing economy gender ethnicity and family structure this article employs population survey data for trinidad and tobago to investigate the likelihood of being married both legal and common law in the present or the past as compared to being never married in a developing economy the article finds support for the sex specialized theory of marital formation with men valued more and women valued less for their economic contributions to the family socioeconomic status and ethnicity play an important role in marital formation with sex specialization less likely to occur among africans than the more advantaged ethnic groups one of the consistent findings is that family structure matters crucially in predicting both legal and common law marriages for example living in a large multigenerational household tends to impact the likelihood of marriage as compared to remaining single in opposite ways for men and women with men in large households more likely to be married but women less likely to be married

short term strategies for dutch wind power producers to reduce imbalance costs the paper assesses bidding strategies for a wind power producer in the netherlands to this end a three stage stochastic optimization framework is used maximizing wind power producer s profit using the day ahead and cross border intraday market taking into account available interconnection capacity results show that the wind power producer can increase its profits by trading on the intraday market and under certain imbalance prices by intentionally creating imbalances it has been considered uncertainties about prices power forecast and interconnection capacity at the day ahead and intraday timeframes

optimal coordinated wind hydro bidding strategies in day ahead markets wind and hydro technologies represent an important part of the electricity generation sector however there have been few detailed studies that have investigated the synergies resulting from their combined operation to address that we formulate three optimization models where wind and reversible hydro technologies bid in a day ahead market the bidding strategies are divided into three categories 1 separate wind and reversible hydro offers without a physical connection between them 2 separate wind and reversible hydro offers with a physical connection to store by pumping the wind energy surplus and 3 single wind and reversible hydro offers with a physical connection risk is considered in the models by means of the conditional value at risk cvar a comparison of the models and relevant conclusions are drawn from an illustrative case study of the iberian day ahead electricity market

evaluating interconnector investments in the north european electricity system considering fluctuating wind power penetration with increasing amounts of power generation from intermittent sources like wind transmission planning has not only to account for the expected load curve but also for the stochasticity of volatile power infeeds moreover investments in power generation are no longer centrally planned in deregulated power markets but rather decided on competitive grounds by individual power companies this poses particular challenges when it comes to evaluating the benefits of increased interconnection capacities in large scale systems like the european transmission system within this article an approach is presented which allows assessing the benefits of interconnector investments in the presence of stochastic power infeed and endogenous power plant investments this model uses typical days and hours as well as recombining trees to represent both load and infeed fluctuations an application is presented covering 30 european countries and simultaneously optimizing generation investments and dispatch as well as utilization of transmission lines the model is used to evaluate the benefits of further line extensions between the european mainland and northern european countries we compute welfare gains and the distribution of these gains within a business as usual scenario up to 2030

wind balancing costs in a power system with high wind penetration evidence from portugal abstract the growth of intermittent renewable power generation has been drawing attention to the design of balancing markets portugal is an interesting case study because wind generation already accounts for a high fraction of demand 23 in 2012 2016 but still there are no economic incentives for efficient wind forecasting wind balancing costs are passed to end consumers we analyze the evolution of the balancing market from 2012 to 2016 using actual market data we find wind balancing costs around 2 euros per mwh of generated energy one main reason for these low costs is the existence of a robust transmission grid which allows for the compensation of positive with negative wind imbalances across the system nevertheless the results suggest that final consumers could save several million euros per year if wind generators were made responsible for the economic cost of their imbalances in line with other european markets