Energy Cost Analysis Research Articles

An Economic Analysis of Grid-connected Hybrid Energy Systems

In this article, a pilot area was selected and the renewable energy potential for this region has been evaluated by making an energy cost analysis. The study evaluates the feasibility of utilizing solar and wind energy with hydrogen as a backup power unit to meet the electricity requirements of the pilot region in conjunction with conventional grid-based electricity. In order to simulate the operation of the system and to calculate the technical/economical parameters, micropower optimization program HOMER was used. HOMER requires some input values for the area and ranges the feasible system configurations according to the net present cost (system cost) using these inputs. The pilot region where the renewable based energy will be used is determined to be The Electrics and Electronics faculty, Istanbul Technical University.

The cost of energy analysis and energy planning for emerging, fossil fuel power plants based on the climate change scenarios

This paper studies the cost of energy (COE) for several emerging, fossil fuel power plants such as an integrated gasification combined cycle (IGCC) power plant, a natural gas combined cycle (NGCC) power plant, and a pulverized coal (PC) power plant under three different scenarios defined by the International Energy Agency (IEA). In order to compare the COE for each power plant more realistically, the concept of the 20-year levelized cost of energy (LCOE) was used. Since previous LCOE analyses did not consider the changes in fuel price and CO 2 prices, the reliability of previous LCOE results is not good enough to be acceptable for future energy planning. In this study, modified LCOEs, which consider the changes in fuel and CO 2 prices with respect to the different scenarios were suggested in order to increase the reliability of the economic comparisons of emerging, fossil power plants. In addition, energy planning was done in order to present the applicability of the proposed calculation method for the COE.

Economic analysis of standalone and grid connected hybrid energy systems

A pilot region was selected and cost analysis of using renewable energy sources with a hydrogen system for that region’s energy demand is introduced, in a techno-economic perspective, in this paper. The renewable energy potential for the region was evaluated by implementing energy cost analysis. The study also evaluates the feasibility of utilizing solar and wind energy with hydrogen as a storage unit to meet the electricity requirements of the pilot region as a standalone system and in conjunction with the conventional grid based electricity. In order to simulate the operation of the system and to calculate the technical and economic parameters, micropower optimization program Homer (NREL, US) was used in this study. Homer requires some input values, such as technological options, cost of components, and resource compliance; and then the program ranges the feasible system configurations according to the net present cost (system cost) by using these inputs. The pilot region in this study, where the renewable based energy will be used, is determined to be Electrics & Electronics Faculty, Istanbul Technical University.

Functional mapping of factor VIII C2 domain

The factor VIII (FVIII) is a cofactor of the coagulation cascade. The FVIII C2 domain is a critical domain that participates in the interactions with the von Willebrand factor and the phospholipidic surfaces. To assess the importance of each residue of this domain in the maintenance of the structure and the function of FVIII, a number (n=139) of mutants were generated by substituting the original residues, from Ser2173 to Gly2325, by an alanine. Mutants were built within a complete B domain-deleted FVIII and expressed in COS-1 cells. Mutant antigen levels and procoagulant activities were measured. Two in silico analyses, a sliding average procedure and an analysis of the mutation energy cost were conducted in parallel on the FVIII structure. Both results were in agreement with the functional data, and illustrated the benefit of using such strategies prior to targeting specific residues in the aim of generating active recombinant molecules. The functional assays identify the residues that are important to maintaining the structure of the C2 domain, mainly those forming β-sheet, and those that can afford substitution, establishing a detailed functional relation with the available crystallographic data. This study provided a comprehensive functional mapping of the FVIII C2 domain and discussed the implication of specific residues in respect to the maintenance in the activity and structure stability, the efficiency in secretion, the binding to phospholipids and the formation of epitope.

Primary energy and economic analysis of combined heating, cooling and power systems

Abstract In this paper, the primary energy consumption and the economic viability of a combined heating, cooling and power (CHCP) system are derived. The focus is on small-scale applications in the range below 100 kWH/70 kWC/58 kWel. CHCP is discussed between the boundaries of combined heating and power (CHP) and combined cooling and power (CCP) using a lumped parameter model. The method used is independent of a specific load profile for a building; only the full-load hours for heating and cooling are needed to predict the economic viability. German data is used for the example. A sensitivity analysis reveals the parameters with the highest impact on the primary energy consumption and the energy costs. The primary energy factors, the energy prices and the electric efficiency of the CHP are the dominating parameters. Increasing electricity prices favour the introduction of CHP and CHCP systems whereas increasing gas prices inhibit it. The energy cost analysis is extended to an economic analysis taking maintenance and investment costs into account. One result of this paper is a simple diagram which shows how many annual operation hours are needed for heating and cooling with CHCP to be more economical than a reference system.

Efficiency of CO2 Dissociation in a Radio-Frequency Discharge

One possible solution to mitigating the effects of high atmospheric concentrations of carbon dioxide (CO2) is the use of a plasma source to break apart the molecule into carbon monoxide (CO) and oxygen. This work experimentally investigates the efficiency of dissociation of CO2 in a 1-kW radio-frequency (rf) plasma source operating at 13.56-MHz in a low-pressure discharge. Mass spectrometry diagnostics are used to determine the species present in the discharge, and these measurements are used to calculate the energy efficiency and conversion efficiency of CO2 dissociation in the rf plasma source. Experimental results have found that the conversion efficiency of CO2 to CO can reach values near 90%, however energy efficiency reaches a maximum of 3%. A theoretical energy cost analysis is also given as a method to evaluate the effectiveness of any plasma system designed for CO2 emissions reduction.

A comparative study on energy use and cost analysis of potato production under different farming technologies in Hamadan province of Iran

Abstract The aim of this study was to determine the amount of input–output energy used in potato production and to make an economic analysis of potato production in Hamadan province, Iran. Data for the production of potatoes were collected from 100 producers by using a face to face questionnaire method. The population investigated was divided into two groups. Group I was consisted of 68 farmers (owner of machinery and high level of farming technology) and Group II of 32 farmers (non-owner of machinery and low level of farming technology). The results revealed that 153071.40 MJ ha−1 energy consumed by Group I and 157151.12 MJ ha−1 energy consumed by Group II. The energy ratio, energy productivity, specific energy, net energy gain and energy intensiveness were calculated. The net energy of potato production in Group I and Group II was 4110.95 MJ ha−1 and −21744.67 MJ ha−1, respectively. Cost analysis showed that total cost of potato production in Groups I and II were 4784.68 and 4172.64 $ ha−1, respectively. The corresponding, benefit to cost ratio from potato production in the surveyed groups were 1.09 and 0.96, respectively. It was concluded that extension activities are needed to improve the efficiency of energy consumption in potato production.

Energy Storage Systems Markets, Value and Cost Analysis

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Potential for biofuel development in Tihvin and Boksitogorsk districts of the Leningrad region — The analysis of energy wood supply systems and costs

The existing and potential energy wood supply systems have been compared in terms of cost efficiency in Tihvin and Boksitogorsk districts of the Leningrad region to find optimal supply systems. In most cases the supply systems based on the cut-to-length method have the highest cost efficiency and provides costs of energy wood between 18.8 and 25.8 € m − 3 . For commercial thinnings the supply systems with manual felling are the most cost effective. In final fellings bigger average stem volume allows more productive use of harvesters that provides lower costs than systems with manual cutting. The total supply cost of energy wood from thinnings is higher compared to final fellings. Costs of energy wood cannot compete with the local price of coal and natural gas. However, energy wood is cheaper than heavy oil if transporting distances are shorter than 50 km. Main reasons for high supply costs of energy wood are low productivity of felling, hauling and transportation. Cost efficiency of energy wood supply can be improved through learning process and the use of modern machines.

Predicting Energy Saving and Life-Cycle Cost Analysis for Lighting and Daylighting Schemes

Energy-efficient lighting installations, together with dimming controls, can make a good contribution to building energy conservation. Energy-efficient lamp fittings provide high light-output values with less power consumption, and electronic circuitry is more efficient than conventional ballasts. Dimming controls can lower lamp output to save energy when illuminance from daylight and light fittings exceeds the target value. This article studies lighting energy consumption and cost analysis when such lighting schemes are used. The findings would be useful for planning green and sustainable energy schemes and applicable to other spaces with similar architectural layouts and lighting control systems.

Energy Recovery Efficiency and Cost Analysis of VOC Thermal Oxidation Pollution Control Technology

Thermal oxidation of VOC is extremely energy intensive, and necessitates high efficiency heat recovery from the exhaust heat. In this paper, two independent parameters heat recovery factor (HRF) and equipment cost factor (ECF) are introduced. HRF and ECF can be used to evaluate separately the merits of energy efficiency and cost effectiveness of VOC oxidation systems. Another parameter equipment cost against heat recovery (ECHR) which is a function of HRF and ECF is introduced to evaluate the merit of different systems for the thermal oxidation of VOC. Respective cost models were derived for recuperative thermal oxidizer (TO) and regenerative thermal oxidizer (RTO). Application examples are presented to show the use and the importance of these parameters. An application examples show that TO has a lower ECF while RTO has a higher HRF. However when analyzed using ECHR, RTO would be of advantage economically in longer periods of use. The analytical models presented can be applied in similar environmental protection systems.

Gait in adolescent idiopathic scoliosis: energy cost analysis

Walking is a very common activity for the human body. It is so common that the musculoskeletal and cardiovascular systems are optimized to have the minimum energetic cost at 4 km/h (spontaneous speed). A previous study showed that lumbar and thoracolumbar adolescent idiopathic scoliosis (AIS) patients exhibit a reduction of shoulder, pelvic, and hip frontal mobility during gait. A longer contraction duration of the spinal and pelvic muscles was also noted. The energetic cost (C) of walking is normally linked to the actual mechanical work muscles have to perform. This total mechanical work (W(tot)) can be divided in two parts: the work needed to move the shoulders and lower limbs relative to the center of mass of the body (COM(b)) is known as the internal work (W(int)), whereas additional work, known as external work (W(ext)), is needed to accelerate and lift up the COM(b) relative to the ground. Normally, the COM(b) goes up and down by 3 cm with every step. Pathological walking usually leads to an increase in W (tot) (often because of increased vertical displacement of the COM(b)), and consequently, it increases the energetic cost. The goal of this study is to investigate the effects of scoliosis and scoliosis severity on the mechanical work and energetic cost of walking. Fifty-four female subjects aged 12 to 17 were used in this study. Thirteen healthy girls were in the control group, 12 were in scoliosis group 1 (Cobb angle [Cb] < or = 20 degrees), 13 were in scoliosis group 2 (20 degrees < Cb < 40 degrees), and 16 were in scoliosis group 3 (Cb > or = 40 degrees). They were assessed by physical examination and gait analysis. The 41 scoliotic patients had an untreated progressive left thoracolumbar or lumbar AIS. During gait analysis, the subject was asked to walk on a treadmill at 4 km h(-1). Movements of the limbs were followed by six infrared cameras, which tracked markers fixed on the body. W(int) was calculated from the kinematics. The movements of the COM(b) were derived from the ground reaction forces, and W(ext) was calculated from the force signal. W(tot) was equal to W(int) + W(ext). Oxygen consumption VO2 was measured with a mask to calculate energetic cost (C) and muscular efficiency (W(tot)/C). Statistical comparisons between the groups were performed using an analysis of variance (ANOVA). The external work (W(ext)) and internal work (W(int)) were both reduced from 7 to 22% as a function of the severity of the scoliosis curve. Overall, the total muscular mechanical work (W(tot)) was reduced from 7% to 13% in the scoliosis patients. Within scoliosis groups, the W(ext) for the group 1 (Cb > or = 20 degrees) and 2 (20 < or = Cb < or = 40 degrees) was significantly different from group 3 (Cb > or = 40 degrees). No significant differences were observed between scoliosis groups for the W(int). The W(tot) did not showed any significant difference between scoliosis groups except between group 1 and 3. The energy cost and VO2 were increased by around 30%. As a result Muscle efficiency was significantly decreased by 23% to 32%, but no significant differences related to the severity of the scoliosis were noted. This study shows that scoliosis patients have inefficient muscles during walking. Muscle efficiency was so severely decreased that it could be used as a diagnostic tool, since every scoliosis patient had an average muscle efficiency below 27%, whereas every control had an average muscle efficiency above 27%. The reduction of mechanical work found in scoliotic patients has never been observed in any pathological gait, but it is interpreted as a long term adaptation to economize energy and face poor muscle efficiency. With a relatively stiff gait, scoliosis patients also limit vertical movement of the COM(b) (smoothing the gait) and consequently, reduce W(ext) and W(int). Inefficiency of scoliosis muscles was obvious even in mild scoliosis (group 1, Cb < 20 degrees) and could be related to the prolonged muscle contraction time observed in a previous study (muscle co-contraction).

One-Pass EAP-AKA Authentication in 3G-WLAN Integrated Networks

The incorporation of Wireless Local Area Networks (WLANs) within the third generation (3G) networks materializes the next generation of mobile/wireless systems, named 3G-WLANs integrated networks. This paper proposes an improved authentication procedure for the 3G-WLANs integrated networks that enables a WLAN user to get access to the 3G packet switched services or to the public Internet through the 3G public land mobile network. The proposed procedure reduces significantly the authentication overhead compared to the legacy one, without compromising the provided security services. A security analysis of the proposed authentication procedure is elaborated that ensures the correctness of the authentication procedure, the provision of advanced security services and the elimination of possible attacks that may threaten the proposed authentication procedure. In addition, an energy cost analysis is carried out that compares the energy consumption induced by the legacy and the proposed authentication procedures. Finally, a communication cost analysis is provided that estimates the cost improvement of the proposed over the legacy authentication procedure.

Energy cost analysis of a solar-hydrogen hybrid energy system for stand-alone applications

Three configurations of fuel cell and photovoltaic hybrid systems were evaluated in this paper based on economic constraints. In order to estimate the energy cost of each configuration, sources were sized with an analytical approach. An energy based modelling has been developed with Matlab/Simulink to observe evolution of the system during the period of one year. The simulation results were used for optimizing the configuration costs in order to obtain the most cost effective system. An appropriate system sizing based on the proposed optimization solution, showed that a system composed with a photovoltaic generator, a fuel cell, an electrolizer and a battery can deliver energy in a stand-alone installation with an acceptable cost.

Measurement and improvement of the energy efficiency at pumping stations

Rational and efficient use of energy is essential for sustainable development. In Spain, as in many other countries, electrical energy is the main source of energy in irrigation; therefore, research with the aim of increasing the efficient use of electrical energy should be arranged. The goal of the research performed was to develop a model for analysing energy efficiency at pumping stations, which permitted the determination of the sequence of pump activation that minimised the energy cost for real demand scenarios. The model was calibrated for the pumping station of Tarazona de La Mancha (Spain) by measuring hydraulic and electrical parameters for each pump. One of the main aspects to consider when carrying out the energy cost analysis at pumping stations is to estimate the discharge distribution throughout the irrigation season. The optimum sequence of activation of pumps was the option that best fitted the discharge distribution in terms of efficiency. This paper illustrates that simple electrical and hydraulic measurements at pumping stations can help to improve their management. In the case study, a cost saving of 16% was obtained by changing the regulation of the pumping station. In only one season, the additional costs of applying this methodology (electrical network analysers, flowmeters, and pressure transducers) would have been recovered with the energy efficiency improvement. Results could vary in other cases depending on the discharge distribution and the working points of the pumps.

Decreased Energy Cost and Improved Gait Pattern Using a New Orthosis in Persons With Long-Term Stroke

Thijssen DH, Paulus R, van Uden CJ, Kooloos JG, Hopman MT. Decreased energy cost and improved gait pattern using a new orthosis in persons with long-term stroke. Objective To measure energy cost and gait analysis in persons with stroke with and without a newly developed orthosis. Design Immediate and long-term (3wk) intervention (before-after trial). Setting University medical center. Participants Volunteer sample of 27 persons with long-term (range, 0.6–19y) hemiparetic stroke. Intervention Three-week familiarization to the new walking aid. Main Outcome Measures Energy cost (per distance walked), preferred walking speed (PWS), and step length. Energy cost was examined in all subjects while walking on a treadmill at 3 different velocities (PWS, PWS+30%, PWS−30%) during 3 different situations (without orthosis, with orthosis, after 3-wk orthosis familiarization). Spatiotemporal aspects of the gait pattern were examined using a 6-m instrumented walkway system. Results Using the orthosis immediately decreased energy cost in persons with stroke during walking at the PWS ( P<.001) and significantly increased walking speed ( P<.005) and step length ( P<.001). After 3 weeks of familiarization to the orthosis, energy cost at the PWS and at PWS+30% showed further improvement in energy cost ( P<.05). Conclusions The newly developed orthosis immediately decreases energy cost and improves walking speed and step length in persons with long-term stroke. After only 3 weeks of orthosis familiarization, energy cost shows additional improvement.

A Modular Process Modeling Tool for the Analysis of Energy Use and Cost in the Pulp and Paper Industry

A novel process modeling tool to facilitate the study of how various process changes in the paper dryer section affect the mill-wide energy system has been developed. A model library with steady-state block models describing paper dryers, heat recovery equipment, and auxiliary systems on component level have been developed using the software Extend. Process models are then created from these block models using graphical programming. In this article, the characteristics of the developed tool are described and a case study where the tool is shown to be useful for analyzing the energy performance of a hybrid dryer section is presented.

Energy consumption and cost analysis of local parboiling processes

This study was conducted at Gazole in the Malda district of West Bengal, India, by both the physical monitoring and questionnaire survey to evaluate the local parboiling processes (vessel, small-boiler and medium-boiler). The biomass consumption and head rice yield were measured and the market values were assessed by a questionnaire. The net present worth (NPW), payback period and internal rate of return were also determined. The parboiled rice produced under boiler processes had a higher market value (US$157.4/t) compared to the vessel (US$151.6/t), but required a greater initial investment. The boiler processes were reported to be less tedious and provided a better working environment compared to the vessel. The head rice yield was estimated to be 65.9%, 69.2% and 66.6% for the vessel, small-boiler and medium-boiler process, respectively. The medium-boiler consumed the lowest amount of energy (1659 MJ/t) compared to the others. The cost analysis of the parboiling processes revealed that all the processes are economically viable, but the small-boiler was found to be the most attractive, having the shortest payback period and the highest internal rate of return. The local parboiling process can be improved in terms of the energy consumption and the market value of the rice by adopting the medium-boiler process.

05/01054 Probabilistic analysis of electrical energy costs comparing: production costs for gas, coal and nuclear power plants

05/01054 Probabilistic analysis of electrical energy costs comparing: production costs for gas, coal and nuclear power plants

Energy expenditure and gait characteristics of a bilateral amputee walking with C-leg prostheses compared with stubby and conventional articulating prostheses

Perry J, Burnfield JM, Newsam CJ, Conley P. Energy expenditure and gait characteristics of a bilateral amputee walking with C-Leg prostheses compared with stubby and conventional articulating prostheses. Objective To compare energy cost and stride characteristics during walking with 3 different types of prostheses in a person with bilateral knee disarticulations. Design Single-case study. Setting Pathokinesiology laboratory. Participant A subject with bilateral knee disarticulations and bilateral transradial amputations secondary to meningococcemia with purpura fulminans. Interventions Not applicable. Main outcome measures Energy cost, stride characteristics, and motion analysis. Results When wearing the C-Leg prostheses, the subject walked the farthest and fastest, with an overall lower rate of oxygen consumption and oxygen cost compared with walking with either of the other prostheses. Gait analysis while the patient was wearing the C-Leg prostheses revealed premature hip extension, absence of knee flexion during loading response, and a rate of swing in the referent range. Conclusions Walking in a C-leg was the most efficient method of ambulation for our subject.