A Review of Tidal and Wave Energy in Southern Waters of Iran

This paper discussed the historical review and current status of tidal current energy, problems, and challenges in this energy commercialization. Fossil fuels are nonreplicable and also have negative greenhouse effects on the environment, so the world needs new and sustainable energy resources such as the ocean, wind, solar, biofuels, etc. This review paper focused on the initiative tidal current energy technology and efforts in the development of such energy to extract power from. Iran’s southern waters have been selected in this review. Some former projects and studies, current status, and impact of the tidal current and wave energy on the environment and aquatic life are discussed. Also, the limitations, challenges, and problems in the way of using this energy and infrastructure to transfer the generated power such as grid connections are proposed. It is decided that Chabahar, Bushehr, and Khowr-Moussa are the best locations for harnessing tides and wave energy. This study is among the first review of works done in the aspect of the tidal current energy in Iran and the results will help the investors, policymakers, companies, and researchers to have access to a comprehensive list of up-to-date studies and statistics to better understand the current situation to secure the projects in this field

Investigating the Potential Impact of Wind Farms on Lake Erie

Our traditional energy sources are mainly non-renewable resources like coal and oil. These fuels, when burned, have a negative impact on our environment due to release of greenhouse gases, and they are not replenishable. So, the world needs other sources of energy to prevent an environmental crisis. Green energy produced from sources like wind, solar, geothermal and hydro, etc., is renewable and has much less impact on our environment. In our study, we focused on the potential impact of wind farms on Lake Eries dynamic and thermal structure. We used COHERENS (a Coupled Hydrodynamical-Ecological model for Regional and Shelf Seas) numerical software for the simulations. They were applied in 1 and 3 dimensions. In both cases, we used real wind speed and other meteorological data including atmospheric pressure, air temperature, humidity and cloud cover to simulate possible temperature and current variations over the ice-free season in Lake Erie. We worked on Erie, since this lake has the highest potential for offshore wind turbine installation due to its proximity to population centres and its shallow depth. In 1D mode, vertical profiles of temperature and water currents are driven by solar radiation and surface fluxes derived from observed three-hourly meteorological data, coupled with vertical mixing processes within the water column. Results are obtained for nine months of open (ice-free) water, March to November 2013, with different water depths of 10, 25 and 60 m. The model was run twice. In the second run, we used a reduced wind speed associated with the potential effect of wind turbines. For initial calculations, we used 25 percent reduction as a representative value. In 3D mode, we investigated the circulation and thermocline pattern for the months of May to October, 2005. As in the 1D mode, the model was run twice. The model is forced by solar radiation plus momentum and heat fluxes (sensible and latent) at the surface derived from North American Regional Reanalysis (NARR) and Canada Centre for Inland Waters (CCIW) data, plus initial conditions and with tributary flows represented as current vectors at river mouths. The Detroit River is the main inflow while outflow is via the Niagara River. With precipitation and evaporation balanced there was net zero accumulation of water in the basin. In the first run we explored water circulation patterns and the thermal structure (including the thermocline), of the lake and in the second run, we simulated the same parameters but added a large wind farm with 432 offshore turbines located in the shallow southern waters of the central basin. We compared our first run COHERENS output with both the Princeton Ocean Model (POM), and the Estuary and Lake Computer Model (ELCOM) results, run by the National Oceanic and Atmospheric Administration (NOAA) and the Canada Centre for Inland Waters (CCIW- Environment Canada), respectively. Generally, good agreement was achieved with these runs, which in turn had compared satisfactorily with field measurements. Results from the second run are used to estimate the potential impact of a large wind farm on the circulation and thermal structure in the areas of the lake within and around the wind farm

Metafrontier efficiency analysis with convex and non-convex metatechnologies by stochastic nonparametric envelopment of data

This paper suggests how stochastic nonparametric envelopment of data (StoNED) can be extended as an estimator in the metafrontier efficiency analysis. Both convex and non-convex metatechnologies are formed and a semi-nonparametric estimation technique for the corresponding metafrontiers is developed. Remaining consistent with the metafrontier theory, the resulting estimated metafrontiers always envelope the estimated group frontiers

A linear programming approach to efficiency evaluation in nonconvex metatechnologies

The notions of metatechnology and metafrontier arise in applications of data envelopment analysis (DEA) in which decision making units (DMUs) are not sufficiently homogeneous to be considered as operating in the same technology. In this case, DMUs are partitioned into different groups, each operating in the same technology. In contrast, the metatechnology includes all DMUs and represents all production possibilities that can in principle be achieved in different production environments. Often, the metatechnology cannot be assumed to be a convex set. In such cases benchmarking a DMU against the common metafrontier requires implementing either an enumeration algorithm and solving a linear program at each of its steps, or solving an equivalent mixed integer linear program. In this paper we show that the same task can be accomplished by solving a single linear program. We also show that its dual can be used for the returns-to-scale characterization of efficient DMUs on the metafrontier

A linear programming approach to efficiency evaluation in nonconvex metatechnologies

The notions of metatechnology and metafrontier arise in applications of data envelopment analysis (DEA) in which decision making units (DMUs) are not sufficiently homogeneous to be considered as operating in the same technology. In this case, DMUs are partitioned into different groups, each operating in the same technology. In contrast, the metatechnology includes all DMUs and represents all production possibilities that can in principle be achieved in different production environments. Often, the metatechnology cannot be assumed to be a convex set. In such cases benchmarking a DMU against the common metafrontier requires implementing either an enumeration algorithm and solving a linear program at each of its steps, or solving an equivalent mixed integer linear program. In this paper we show that the same task can be accomplished by solving a single linear program. We also show that its dual can be used for the returns-to-scale characterization of efficient DMUs on the metafrontier

Efficiency and Its Impact on the Performance of European Commercial Banks

The paper empirically analyzes the impact of the degree of efficiency on key performance fig-ures of publicly traded European banks in the period from 2005 to 2009. Efficiency is meas-ured by constructing non-parametric frontiers using the technique of data envelopment analysis on the cost, revenue, and profit sides. Decomposition of overall efficiency provides a detailed insight into effective risk and performance drivers in the banking industry. The results of our paper suggest that an increase in pure technical efficiency is related to more volatile assets, which is reflected in lower market values. Allocative and scale efficiency, however, boost capi-tal market performance

A DEA-based incentives system for centrally managed multi-unit organisations

In multi-unit organisations such as a bank and its branches or a national body delivering publicly funded health or education services through local operating units, the need arises to incentivize the units to operate efficiently. In such instances, it is generally accepted that units found to be inefficient can be encouraged to make efficiency savings. However, units which are found to be efficient need to be incentivized in a different manner. It has been suggested that efficient units could be incentivized by some reward compatible with the level to which their attainment exceeds that of the best of the rest, normally referred to as “super-efficiency”. A recent approach to this issue (Varmaz et. al. 2013) has used Data Envelopment Analysis (DEA) models to measure the super-efficiency of the whole system of operating units with and without the involvement of each unit in turn in order to provide incentives. We identify shortcomings in this approach and use it as a starting point to develop a new DEA-based system for incentivizing operating units to operate efficiently for the benefit of the aggregate system of units. Data from a small German retail bank is used to illustrate our method

Analytical and Laboratory Evaluation of the Solubility of Gypsiferous Soils

Gypsum soil is one of the problematic soils because of considerable solubility for Gypsum particles in contact with water. In this research the effects of three factors including; gypsum percent, hydraulic gradient and soil texture were studied on solubility of gypsum soils. To do this, samples of gypsum soils were provided artificially by adding various rates of natural gypsum rock including 0, 5, 10, 20 and 30 percent weight of 3 kinds of soil textures including clay, silty clay and sand. Totally, 15 types of gypsum soils were prepared. Then each of gypsum soils were leached under five hydraulic gradients levels 0.5, 1, 2, 5 and 10. The results of the test indicated that the rate of Gypsum in the soil had direct effect on the rate of soluble and by increasing the percent of Gypsum, the rate of solubility was increased. In addition, by increasing hydraulic gradient, the speed of water existing soil media in a specified time was increased and also higher rate of Gypsum was derived. Also the soil texture has a considerable effect on the rate of solubility of soil. In this study, rate of solubility of gypsum soils with sandy soils was determined as 1.5 to 2 times more than the rate of clay soils. The   statistical   results show the highest impact of gypsum percentage and lowest impact of hydraulic gradient soil on solubility of particles in different types of soils and it has no significant effect on the overall equation of the soil texture