Motor systems energy efficiency supply curves: A methodology for assessing the energy efficiency potential of industrial motor systems

Motor-driven equipment accounts for approximately 60% of manufacturing final electricity use worldwide. A major barrier to effective policymaking, and to more global acceptance of the energy efficiency potential in industrial motor systems, is the lack of a transparent methodology for quantifying the magnitude and cost-effectiveness of these energy savings. This paper presents the results of groundbreaking analyses conducted for five countries and one region to begin to address this barrier. Using a combination of expert opinion and available data from the United States, Canada, the European Union, Thailand, Vietnam, and Brazil, bottom-up energy efficiency supply curve models were constructed to estimate the cost-effective electricity efficiency potentials and CO₂ emission reduction for three types of motor systems (compressed air, pumping, and fan) in industry for the selected countries/region. Based on these analyses, the share of cost-effective electricity saving potential of these systems as compared to the total motor system energy use in the base year varies between 27% and 49% for pumping, 21% and 47% for compressed air, and 14% and 46% for fan systems. The total technical saving potential varies between 43% and 57% for pumping, 29% and 56% for compressed air, and 27% and 46% for fan systems.     

New method for assessing the performance of agricultural biogas plants

Around 5000 agricultural biogas plants were operating in Germany by the end of 2009. There is a recognized need for their assessment, comparison and performance improvement. Prerequisites for their reliable assessment include: 1) detailed and reliable performance data, 2) defined criteria for the assessment, and 3) comprehensive method. The limitations of existing assessment methods have been reviewed. The new method developed for assessing the overall performance of biogas plants is focused on four assessment aspects: biogas production, biogas utilization, environmental impact and socio-economic efficiency. Each assessment aspect was determined by two performance criteria. The method is based on fuzzy set theory and fuzzy mathematics, which enables use of imprecise and uncertain data. Incorporation of enough expertise from the field of biogas technology was enabled in this method as well. Pre-assessment of future biogas plants in their planning phase is possible, contributing to their effective development. The reliability of the method was tested using data from ten monitored biogas plants. The assessment of the ten biogas plants showed that biogas utilization is the aspect with the largest potential for performance improvement, by increasing the external heat utilization. The method developed is adjustable to accommodate new developments related to biogas technology and biogas plants in any geographical region. Future research should be focused on definition and inclusion of more assessment criteria and on developing the methods that are capable to handle compensation between individual criteria.     

Criteria for the decomposition of energy systems in local/global optimizations

The decomposition of an energy system into subsystems of reduced complexity, to be optimized separately, but in a way compatible with the optimum of the global system, has been recognized as a viable solution to the problem of the design optimization of highly integrated, complex energy systems. Iterative Local/Global Optimization (ILGO) and its dynamic extension (DILGO) permit the decomposition of the global problem into smaller subproblems to be optimized separately, guaranteeing in the process that the subproblem optima eventually converge after a small number of iterations to or near to the optimum of the original global problem. The aim of this paper is to analyze the criteria for energy system decomposition, in particular with regard to the formulation of the separate subproblems and to the imposition of the constraints that affect the coupling of two or more subsystems. Three general decomposition criteria are identified and discussed with simple examples to let the mathematical formulation be analyzed critically.     

Measuring global effectiveness of integrated electric energy systems

In the energy sector, significant investments were made to improve the characteristics of the existing integrated electrical system favoring the transition to a more sustainable, efficient, flexible, reliable and high quality system. Therefore, it is required to have reliable and robust metrics that try to include these concepts in the form of indicators for the KPI and its subsequent analysis. This paper addresses that problem and in order to tackle it introduces a novel methodology to measure the effectiveness of an integrated electrical system. Such methodology is based on the extension of the OEE concept to the energetic domain considering the multiple uncertain factors affecting OEE, and establishing a relation among them through the Planning Factor (PF), which relate strategic and operational concepts. In the experimental part of the paper, we have used this novel methodology to analyze and measure the effectiveness of the Spanish integrated electrical system without losing generality, and using a confidence interval of 95% an OOEE of 0.96 and SOEE of 0.652 have been obtained, which classifies the Spanish system as an advanced one. In this way, different settings or electrical systems can be compared an assessed.     

Exergy method for the diagnosis of energy systems using measured data

The use of exergetic and thermoeconomic analysis for the diagnosis of efficiency reductions in energy systems has been widely discussed in literature. Several procedures, based on thermoeconomic analysis with the aim of locating and quantifying malfunctions, have been proposed and applied to operating plants.     

Development of wind energy systems for New England islands

The 3000 plus islands of New England with their varying electrical needs and high electricity costs present an opportunity for renewable energy development. This paper summarizes the results of ongoing wind energy projects carried out by the University of Massachusetts for the development of renewable energy on several of these islands. In addition to technical–economic issues, the work has addressed potential environmental and political problems that might arise with the installation of such systems. Summaries of four selected case studies involving this work are given in this paper. The overall analysis method used to study each of these studies is described, and the example case studies present a status of the work to date on each of these projects.     

A probabilistic method for the evaluation of the performance ofwind-diesel energy systems

The method takes into account the constraint that the wind generation must not exceed a certain percentage of the system load, which is imposed for reliability reasons. The method efficiently computes the statistics of the wind generation and the diesel plant loading based on the statistics of the wind speed and the system load demand. The performance of the method is demonstrated with computational results. An example of obtaining the optimum wind penetration for an existing diesel system is presented     

A general design method for closed-loop solar energy systems

A general design method is presented for closed loop energy systems consisting of solar collectors, sensible energy storage and a closed-loop flow circuit in which thermal energy is supplied (through heat exchange) to a load above a specified minimum temperature. It is assumed that the energy supplied to the load is used at a constant thermal efficiency. Computer simulations were used to estimate the long-term thermal performance of these systems, and correlations between the system performance and the system design parameters, such as the collector characteristics, load size, climatic data, and the minimum useful temperature, are presented.     

Novel method for setting up the relay protection of power systems containing renewable energy sources and hydrogen energy storage systems

Integration of renewable energy sources (RES) together with energy storage systems (ESS) changes processes in electric power systems (EPS) significantly. Specifically, rate of change and the lowest values of operating conditions during the emergencies are got influenced. Such changes can cause incorrect actions of relay protection (RP) as it was designed and adjusted with no regard for influence of RES and ESS. Detailed research on processes during the different normal and abnormal modes in both EPS and primary transducers and also in RP devices should be done to take preventive actions. To do this research mathematical modeling based on detailed and authentic models of all elements including RP should be used. HRTSim (which was developed by authors) software for simulating EPS provides the opportunity to create such models of EPS of any size without simplifications and limits. Using of this instrument together with detailed mathematical models of RP which were developed before provided the opportunity to investigate them rigorously in RES-integrated EPS. Settings providing adequate action of RP in certain conditions were performed as a result of this investigation. Fragments of these investigations are performed in this paper. Results of these investigations would be useful for designing new methods and tools of RP adjustment.     

New proposal for photovoltaic-thermal solar energy utilization method

One of the most effective methods of utilizing solar energy is to use the sunlight and solar thermal energy such as a photovoltaic-thermal panel (PV/T panel) simultaneously. From such a viewpoint, systems using various kinds of PV panels were constructed in the world. In these panels, solar cells are set up at an absorber collecting solar thermal energy. Therefore, temperature of solar cell increases up to the prescribed temperature of thermal energy use, although it is lower than the cell temperature when using only solar cell panel. For maintaining cell conversion efficiency at the standard conditions, it is necessary to keep the cell at lower temperature. In this paper, electric and thermal energy obtained from a PV/T panel is evaluated in terms of energy. Based on this evaluation, the method of not to decrease cell conversion efficiency with collecting solar thermal energy was proposed.     

Growth in global energy demand and contribution of alternative supply systems

Growth in global energy demand since the end of World War II has been nearly constant at a rate of 5.3% each year. When energy demand is projected into the future, the basic question is how long such an exponentially growing global energy use can continue, and a more accurate analysis than projecting exponential growth indefinitely into the future is certainly desirable.In this analysis, nine political/geographical segments are used and it is shown that the less developed countries will grow much more rapidly than the industrialized countries. Analyses of individual nations- or at least small sub-divisions of the nine segments—based on factors such as population growth, availability of resources, capability of food production, potential for formation of capital, and prospects for political stability are necessary in order to achieve reasonable accuracy in projections.Such concepts of growth suggest very strongly that fifty years from now the global energy demand will be approximately 31 TW, with over half the total coming from the developing world. This will present unusual opportunities for employing alternative energy supply systems. In rapidly growing situations, market penetration of new technologies is easier, but, in any event, the magnitude of the effort required is enormous if alternative supply systems are to make major contributions to the total.As a target, the 17 TW demand in AD2025 from the developing world might be met by the following supply system: TW Solar Heating (water and air) 1.5 Biomass (firewood, charcoal, alcohol) 3.5 Wind 0.8 Hydro and Geothermal 2.2 Fission 0.5 Fossil fuels (oil, gas, coal) 8.5 Total 17.0To place these in perspective and to indicate the size of the task involved, note that the total world energy demand in 1975 was only 7.3 TW. The target calls for alternative supply systems in the developing world alone to exceed the present world total within 50 yr. Contributions from hydro and geothermal sources (in the developing world) approach the present total energy demand in North America—one-third of the world's total. Biomass as a supply system is targeted for 1.5 times the present N. American total. While this is a formidable target, I believe that if economic growth throughout the world is to continue and if the gap between the rich and poor countries is to shrink, it is, in fact, a modest social goal.     

New energy and exergy parameters for geothermal district heating systems

This paper introduces four new parameters, namely energetic renewability ratio, exergetic renewability ratio, energetic reinjection ratio, and exergetic reinjection ratio for geothermal district energy systems. These parameters are applied to Edremit Geothermal District Heating System (GDHS) in Balikesir, Turkey for daily, monthly and yearly assessments and their variations are studied. In addition, the actual data are regressed to obtain some applied correlations for practical use. Some results follow: (i) Both energetic and exergetic renewability ratios decrease with decreasing temperature in heating season and increasing temperature in the summer. (ii) Both energetic and exergetic reinjection ratios increase with decreasing temperature for heating season and increase with increasing temperature for summer season.     

A probabilistic method for the evaluation of the reliability ofstand alone wind energy systems

The author describes a probabilistic method for the computation of the loss of load probability and the expected unserved energy of a stand-alone wind energy system. The system consists of a wind generator and a storage battery supplying the consumer load. The statistics of the surplus generation (excess wind generation over load demand) time series are computed and used for the calculation of the desired reliability indices. It is shown, that in the probability computations, the serial correlation of the surplus generation cannot be ignored. The performance of the developed method is demonstrated with computational results. Some results useful for the design of stand-alone wind energy systems are also presented     

Modelling of thermal energy storage in industrial energy systems the method development of MIND

Industrial energy efficiency is of vital importance as regards environment and industrial profitability. Optimisation of industrial energy systems may show a way towards improved use of resources in energy supply as well as in production processes.The deregulation of the electricity market in some countries increases flexibility in electricity contracts. Taking advantage of the price structure in these contracts is one of the ways to minimise the energy costs and decrease the influence on the environment. Thermal energy stores are very suitable facilities for achieving these goals, having the capability of moving energy use from one period of time to another and thereby influencing not only energy cost but also costs related to power demand if electric energy use is involved.In this paper, the influence on energy costs, energy and material flows resulting from the use of energy storage is discussed. Energy storage has been modelled by using MIND (Method for analysis of INDustrial energy systems) in the form that has recently been developed by the author. A case study from the pulp and paper industry has been used to verify this.     

Fuzzy TOPSIS method for ranking renewable energy supply systems in Turkey

Multi-Criteria Decision Making (MCDM) techniques are gaining popularity in energy supply systems. The aim of this paper is to develop the multi-criteria decision support framework for ranking renewable energy supply systems in Turkey. Given the selection of renewable energy supply systems involves many conflicting criteria, multi criteria decision methods (Fuzzy TOPSIS) were employed for the analysis. The Interval Shannon's Entropy methodology was used to determine weight values of the criteria. In this study, α = 0.1, 0.5 and 0.9 values based sensitivity analysis were performed. Three α-cutting levels were identical to the sequence of alternatives. According to result, the first criterion in preference ranking of renewable energy sources in Turkey is the Amount of Energy Produced, followed by the ranking systems Land use, Operation and maintenance cost, Installed capacity, Efficiency, Payback period, Investment cost, Job creation, and Value of CO₂ emission. Thus the multi-criteria analysis showed that the Hydro Power Station is determined to be the most renewable energy supply system in Turkey. Additionally, the Geothermal Power Station, Regulator and Wind Power Station are determined to be the second, third and fourth, respectively. The government of Turkey should invest, in order of priority, in these systems. The government should also evaluate the projects, which are related to these renewable energy resources.     

A probabilistic method for the evaluation of the performance andthe reliability of wind-diesel energy systems

A probabilistic method for the evaluation of the performance and the reliability of wind-diesel energy systems with constrained wind generation is presented. The method computes the expected annual wind and diesel energy production as well as the system loss of load probability and expected unserved energy by processing the statistics of the wind speed and the system load demand. The performance of the method is demonstrated with computational results     

Designing an index for assessing wind energy potential

To meet the increasing global demand for renewable energy, such as wind energy, an increasing number of wind parks are being constructed worldwide. Finding a suitable location requires a detailed and often costly analysis of local wind conditions. Plain average wind speed maps cannot provide a precise forecast of wind power because of the non-linear relationship between wind speed and production. We suggest a new approach to assess the local wind energy potential. First, meteorological reanalysis data are applied to obtain long-term low-scale wind speed data at specific turbine locations and hub heights. Second, the relation between wind data and energy production is determined via a five parameter logistic function using actual high-frequency energy production data. The resulting wind energy index allows for a turbine-specific estimation of the expected wind power at an unobserved location. A map of the wind power potential for Germany exemplifies our approach.     

Insights for global energy interconnection from China renewable energy development

Vigorously developing global renewable energy such as wind energy, solar energy, and hydropower and realizing global clean resource sharing are paramount driving forces for building the Global Energy Interconnection (GEI). With the help of a comparative analysis of renewable energy development and global renewable energy development scenarios, this paper expounds on the similarities between China1 and global renewable energy development. Based on the analysis of renewable energy development and the status of global renewable energy development in China, this paper summarizes the relevant experience and problems of renewable energy development in China. According to these problems, this paper also puts forward the corresponding solutions and measures, that is, to promote the healthy and steady development of renewable energy in China through the source-network-load-storage and market coordination. Finally, by analyzing the development requirements and current foundation of GEI, insights and suggestions are proposed for the future development of renewable energy for the GEI construction.     

A review of the potential water quality impacts of tidal renewable energy systems

The continued increase in the demand for energy, growing recognition of climate change impacts, high oil and gas prices and the rapid depletion of fossil fuel reserves have led to an increased interest in the mass generation of electricity from renewable sources. Traditionally, this has been pursed through riverine hydropower plants, with onshore wind systems growing steadily in popularity and importance over the years. Other renewable energy resources, which were previously not economically attractive or technically feasible for large scale exploitation, are now being considered to form a significant part of the energy mix. Amongst these, marine and in particular, tidal energy resource has become a serious candidate for undergoing mass exploitation in the near future, particularly in places with a tidal range of 4 m or more. Tidal renewable energy systems are designed to extract the kinetic or potential energy flow and convert it into electricity. This can be achieved by placing tidal stream turbines in the path of high speed tidal currents or through tidal range schemes, where low head turbines are encapsulated in impoundment structures, much like in low head riverine hydropower schemes. It is thought that these systems, when implemented at scales required to generate substantial amounts of electricity, have the potential to significantly alter the tidal flow characteristics, which could have knock-on impacts on the hydro-environment. This review gathers together knowledge from different research areas to facilitate an evaluation of the potential hydro-environmental impacts of tidal renewable energy systems, with a particular focus on water quality. It highlights the relevance of hydro-environmental modelling in assessing potential impacts of proposed schemes and identifies areas where further research is needed. A case study is presented of recent modelling studies undertaken for the Severn Estuary.     

Mira: A one-repetitive day method for predicting the long-term performance of solar energy systems

A new, one-repetitive day simulation method, named MIRA, has been developed for predicting the long-term performance of a wide variety of solar energy systems. Compared to detailed hourly computer simulations, MIRA requires little computational effort and climatic data bases, while offering comparable accuracy. In the MIRA simulation method, the daily solar radiation profile incorporates both random fluctuations and an inherent time-of-day dependence. Satisfactory agreement between the long-term system performance predictions of the new method and corresponding detailed hourly simulations is demonstrated. The range and magnitude of the predictive accuracy of MIRA and other one-repetitive day methods are illustrated. Their usefulness in sensitivity studies and comparative evaluations of different solar system configurations and control strategies is also discussed.