Aim: To compare the contents of nucleosides from natural Cordyceps sinensis and cultured Cordyceps mycelia, and to study the effect of humidity and heat on the content of nucleosides. Methods: The contents of nucleos...Aim: To compare the contents of nucleosides from natural Cordyceps sinensis and cultured Cordyceps mycelia, and to study the effect of humidity and heat on the content of nucleosides. Methods: The contents of nucleosides were determined by using high performance capillary electrophoresis (HPCE). Beckman P/ACE System 5010 apparatus equipped with a UV detector and a Beckman untreated fused-silica capillary (57 cm 75 mm, 50 cm effective length) was used. Before sample injection, the capillary was rinsed with 1 molL-1 sodium hydroxide solution and running buffer for 5 min, respectively. A voltage of 20 kV was applied for the separation. Pressure injection was 586 kPa for 6 seconds, and the wavelength of detector was 254 nm. The running time was 20 min at 20 oC. The effect of humidity and heat on the contents of nucleosides from natural Cordyceps sinensis and cultured Cordyceps mycelia was observed for 1, 3, 5 and 10 days at temperature 40 oC, and relative humidity 75%. Results: The content of nucleosides from natural Cordyceps sinensis was higher than that from cultured Cordyceps mycelia. But the contents of nucleosides from freshly collected natural Cordyceps sinensis were very low, even below the limit of quantitation. The contents of nucleosides from natural Cordyceps sinensis were significantly increased by humidity and heat, but this phenomenon was not observed in cultured Cordyceps mycelia. Conclusion: There are differences between the nucleosides from natural Cordyceps sinensis and cultured Cordyceps mycelia. The nucleosides in natural Cordyceps sinensis may be derived from the degradation of nucleic acids. This implies that adenosine being used for the quality control of natural Cordyceps sinensis may have to be reconsidered.展开更多
Actual sea condition testing and inspection and evaluation method research are carried out for tidal energy devices to provide scientific and effective technical support for the ocean high-tech achievement transformat...Actual sea condition testing and inspection and evaluation method research are carried out for tidal energy devices to provide scientific and effective technical support for the ocean high-tech achievement transformation and marine renewable energy development. By analyzing three core indicators, including the power output characteristics of the tidal current device, the generating capacity, energy conversion efficiency, proposed the test contents and evaluation methods of indicators are proposed in this paper; and based on the research of wind farms, power quality testing and assessment methods of offshore tidal energy device are proposed; given the security access to the test contents of tidal current energy device, tidal current energy device running conditions in the testing ground are comprehensively assessed.展开更多
AIM: To evaluated the value of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) scan in diagnosis of hepatocellular carcinoma (HCC) and extrahepatic metastases. METHODS: A total...AIM: To evaluated the value of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) scan in diagnosis of hepatocellular carcinoma (HCC) and extrahepatic metastases. METHODS: A total of 138 patients with HCC who had both conventional imaging modalities and 18F-FDG PET/CT scan done between November 2006 and March 2011 were enrolled. Diagnostic value of each imaging modality for detection of extrahepatic metastases was evaluated. Clinical factors and tumor characteristics including PET imaging were analyzed as indicative factors for metastases by univariate and multivariate methods. RESULTS: The accuracy of chest CT was significantly superior compared with the accuracy of PET imaging for detecting lung metastases. The detection rate of metastatic pulmonary nodule ≥ 1 cm was 12/13 (92.3%), when < 1 cm was 2/10 (20%) in PET imaging. The accuracy of PET imaging was significantly superior compared with the accuracy of bone scan for detecting bone metastases. In multivariate analy- sis, increased tumor size (≥ 5 cm) (P = 0.042) and increased average standardized uptake value (SUV) uptake (P = 0.028) were predictive factors for extrahepatic metastases. Isometabolic HCC in PET imaging was inversely correlated in multivariate analysis (P = 0.035). According to the receiver operating characteristic curve, the optimal cutoff of average SUV to predict extrahepatic metastases was 3.4. CONCLUSION: 18F-FDG PET/CT scan is invaluable for detection of lung metastases larger than 1 cm and bone metastases. Primary HCC having larger than 5 cm and increased average SUV uptake more than 3.4 should be considered for extrahepatic metastases.展开更多
Energy-conservation based generation dispatching is the revolutionary change in operation mode which could reduce energy consumption and pollutant emissions, promote power industry restructuring, and achieve sustainab...Energy-conservation based generation dispatching is the revolutionary change in operation mode which could reduce energy consumption and pollutant emissions, promote power industry restructuring, and achieve sustainable development. Social benefit evaluation of the energy-conservation based generation dispatching under the new situation and environment has come into being as an important theoretical issue. A new scenario analysis based social benefit evluating method, which is implemented by comparing the energy., consumption and pollutant emissions of different scenarios defined by the key indicators, i.e., load factor and coal consumption structure, is proposed in the paper. Then the composition of social benefit is analyzed from the point of the dispatching mode and the coal consumption structure. The method proposed is of clear physical meaning. It is not only practical, but also applicable for the implementation of energy-conservation based generation dispatching in diffferent phases and with different goals.展开更多
Considering comprehensive benefit of micro-grid system and consumers,we establish a mathematical model with the goal of the maximum consumer satisfaction and the maximum benefit of power generation side in the view of...Considering comprehensive benefit of micro-grid system and consumers,we establish a mathematical model with the goal of the maximum consumer satisfaction and the maximum benefit of power generation side in the view of energy management.An improved multi-objective local mutation adaptive quantum particle swarm optimization(MO-LM-AQPSO)algorithm is adopted to obtain the Pareto frontier of consumer satisfaction and the benefit of power generation side.The optimal solution of the non-dominant solution is selected with introducing the power shortage and power loss to maximize the benefit of power generation side,and its reasonableness is verified by numerical simulation.Then,translational load and time-of-use electricity price incentive mechanism are considered and reasonable peak-valley price ratio is adopted to guide users to actively participate in demand response.The simulation results show that the reasonable incentive mechanism increases the benefit of power generation side and improves the consumer satisfaction.Also the mechanism maximizes the utilization of renewable energy and effectively reduces the operation cost of the battery.展开更多
In this paper, the generator set of R 〈 x1,x2 〉G is obtained in according to the group G = Gl(n,R). The conditions of G = Gl(n, R) -equivalence of a pair of curves are found in terms of G = Gl(n, R)-invariants...In this paper, the generator set of R 〈 x1,x2 〉G is obtained in according to the group G = Gl(n,R). The conditions of G = Gl(n, R) -equivalence of a pair of curves are found in terms of G = Gl(n, R)-invariants. And the independence of GL(n, R) -invariants is shown.展开更多
This article analyzes the importance of the moderately leading development in electric power industry, and the basic policy of the industry in China. It evaluates if the industry is appropriately developed ahead of ot...This article analyzes the importance of the moderately leading development in electric power industry, and the basic policy of the industry in China. It evaluates if the industry is appropriately developed ahead of other industries from the aspects of legal structuring, planning, electricity pricing mechanism, fixed assets investment, human resources, technological innovation and production and supply capacity etc., and proposes f ive recommendations.展开更多
The main objective of this study is estimating environmental pollution of hybrid biomass and co-generation power plants. Efficiency of direct tapping of biomass is about 15%-20%. Consequently, about 80% of energy woul...The main objective of this study is estimating environmental pollution of hybrid biomass and co-generation power plants. Efficiency of direct tapping of biomass is about 15%-20%. Consequently, about 80% of energy would be waste in this method. While in co-generation power plant, this number could improve to more than 50%. Therefore, to achieve higher efficiency in utilizing biomass energy, co-generation power plants is proposed by using biogas as fuel instead of natural gas. Proposed system would be supplied thermal and electrical energy for non-urban areas of Iran. In this regard, process of fermentation and gas production from biomass in a vertical digester is studied and simulated using analytic methods. Various factors affecting the fermentation, such as temperature, humidity, PH and optimal conditions for the extraction of gas from waste agriculture and animal are also determined. Comparing between the pollution emission from fossil fuel power plants and power plants fed by biomass shows about 88% reduction in greenhouse emission which significant number.展开更多
This research seeks to evaluate the economic benefits to be gained by installing a small-scale wind turbine for a customer with a three-phase electrical supply requirement. The evidence for the claims made in this pap...This research seeks to evaluate the economic benefits to be gained by installing a small-scale wind turbine for a customer with a three-phase electrical supply requirement. The evidence for the claims made in this paper is obtained by using actual data obtained from the installed equipment over a three year period. The objective is to accurately appraise the financial investment using real data. There appears to be limited studies conducted into this type of research, possibly because the renewable energy sector is in the infancy stage in the host country, Ireland. There are some wind energy installations with financial appraisal techniques based on modeled data, which may, or may not, be accurate. The study concludes by claiming that the financial benefits of the wind energy turbine installation had disappointing results when compared to predicted benefits based on modeled data.展开更多
Nowadays IPP's power plant construction is encouraged by the current deregulatory climate. The financing technique employed to implement these projects is often the project financing formula. Under such condition an ...Nowadays IPP's power plant construction is encouraged by the current deregulatory climate. The financing technique employed to implement these projects is often the project financing formula. Under such condition an investor consortium, usually foreigner plan, build, operate the power plant and sell the generated electricity to the host utility. The sale price is determined from the expected IPP's production cost, enhanced from the expected welfare obtainable by selling electricity. This paper proposes a methodology for linking the uncertainty of the future production cost with the price of the electricity generated by an IPP. This is a stochastic approach to the sale price definition problem, while usually conducted through a deterministic procedure.展开更多
The global energy related challenges, mainly due to the worldwide growing energy consumption gone with a reduction ofoil and gas availability, is leading to an increasing interest on hydrogen as energy carrier. Molten...The global energy related challenges, mainly due to the worldwide growing energy consumption gone with a reduction ofoil and gas availability, is leading to an increasing interest on hydrogen as energy carrier. Molten salts at temperatures up to 550 ~C can be used as solar heat carrier and storage system, and hydrogen selective membranes can be used to drive reforming reaction at lower temperatures than conventional (〈 550 ~C), with hydrogen purification achieved thereby. The combination of new technologies such as membranes and membrane reactors, concentrating solar power (CSP) systems and molten salt heat carriers, allows a partial decarbonation of the fossil fuel together with the possibility to carry solar energy in the current natural gas grid. The aim of this work is to present a life cycle assessment of a novel hybrid plant for the production of a mixture of methane and hydrogen, called enriched methane, from a steam reforming reactor whose heat duty is supplied by a molten salt stream heated up by an innovative concentrating solar power (CSP) plant developed by ENEA. The performance of this plant will be evaluated from an environmental point of view by the use of an LCA software (SimaPro7) and compared with the ones of traditional plants (reformer and cracker for the hydrogen production) for the production of enriched methane.展开更多
China has a large potential to reduce CO2 emission in the Asian region. In this study, life cycle analyses of energy supply technologies in China were evaluated for enforcing the clean development mechanism (CDM). W...China has a large potential to reduce CO2 emission in the Asian region. In this study, life cycle analyses of energy supply technologies in China were evaluated for enforcing the clean development mechanism (CDM). Wind power, integrated coal gasification combined cycle (IGCC), natural gas combined cycle (NGCC), and ultra super critical power plant (USC) were chosen as new power generation technologies. The system function of the developed model was enhanced to extend coverage to new technologies for power generation systems in China. CO2 intensities, energy profit ratios, and CO2 emission reductions are estimated based on the assumption that these power plants were constructed at Shanxi, Xinjiang, and Shanghai. Wind power showed the best results with regard to CO2 intensity and energy profit ratio. However, it also has some disadvantages with regard to the utilization factor and the lifetime. It is considered that wind power will become an important part of CDM activities as the utilization factor and the lifetime improve. An NGCC using a natural gas pipeline was found to be most advantageous in reducing CO2 emission. IGCC and USC were inferior to NGCC with regard to energy profit ratios and CO2 emission reductions.展开更多
At Olkaria (Kenya) geothermal energy has been used since 1981, to generate electricity and now there are currently 3 plants with a nominal capacity of 205 MW. Preliminary measurement and evaluation of possible mercu...At Olkaria (Kenya) geothermal energy has been used since 1981, to generate electricity and now there are currently 3 plants with a nominal capacity of 205 MW. Preliminary measurement and evaluation of possible mercury (Hg) emission from two plants has been investigated. Potential atmospheric Hg emission has been determined based on an existing model for estimating the transport of mercury along geothermal fluid flow streams as pertains to energy recovery and conversion from liquid dominated geothermal reservoirs. Hg concentrations, addition, retention and release rates were calculated at a number of locations in the geothermal power plants based on the plant operating parameters and steam flow process (turbine, condenser, non-condensable gas ejector, and cooling tower). Potential Hg emission rates through plume range from 0.455 g/h to 2.17 g/h, or 10-30 mg/h per MWe. The emission per hour per MWe is 130-300 times lower compared to Hg levels reported for 88 MWe five operating geothermal power plants around Mt. Amiata area in Italy. These emissions are coupled with a release of 1.07 kg/h per MW of hydrogen sulphide (HzS). The potential Hg release rates to the environment will depend greatly on the concentration of HzS in the system. Any higher HzS contents may reduce solubility of rig in the brine hence making it to be available in the steam. The volatile Hg may travel with the non-condensable gases as Hg vapour.展开更多
Firstly, the construction background and basic connotations of CNOOC's Green Supply Chain was presented in this paper. Then, a detailed introduction to CNOOC's good practices for building green oil and gas fie...Firstly, the construction background and basic connotations of CNOOC's Green Supply Chain was presented in this paper. Then, a detailed introduction to CNOOC's good practices for building green oil and gas fields, green power plants, green refineries and green chemical plants was given with respect to the establishment of a green production construction and assessment system as well as green exploration, green manufacturing,green products, green sales, green recovery and other aspects. Finally, the effects of the Green Supply Chain established by CNOOC were summarized.展开更多
In this paper,through applying the result of backward stochastic differential equations,it investigates a domination for pricing of the contingent claims by the use of nonlinear infinitesimal generator of process X. T...In this paper,through applying the result of backward stochastic differential equations,it investigates a domination for pricing of the contingent claims by the use of nonlinear infinitesimal generator of process X. This domination provides a guide for valuing the price of the position on the financial market.展开更多
Modern power systems are typically characterized with renewable energies and smart grids.Their developments should be kept at a compatible pace with each other.According to the different structures of the power indust...Modern power systems are typically characterized with renewable energies and smart grids.Their developments should be kept at a compatible pace with each other.According to the different structures of the power industry,such as generation,transmission,distribution,consumption and dispatching,a comprehensive evaluation system for coordinated development of renewable energy and smart grid in"3 levels,4 sections,15 targets"is created.The index system of coordinated development is important to determine the priorities and key areas in smart grids and renewable energies.By the index system of coordinated development,this paper evaluates the status of renewable energy and grid development,and their degree of coordination in China.A quantitative evaluation method to determine the level of coordination between China's renewable energies and smart grids is developed.The total and component coordination levels in China are calculated by an analytic hierarchy process.In conclusion,the degree of coordination in transmission and dispatching is higher, but the extent of electricity consumption is lowest.Therefore,the consumption section should be the first to develop within China.展开更多
DC distribution networks are often employed in isolated power systems like in marine and aeronautical applications. An interesting alternative to DC machines for the supply of DC grids is constituted by a three-phase ...DC distribution networks are often employed in isolated power systems like in marine and aeronautical applications. An interesting alternative to DC machines for the supply of DC grids is constituted by a three-phase alternator feeding an AC/DC rectifier. In this paper, alternative solutions are investigated where the AC alternator is equipped with more (iV) three-phase windings and feeds the DC load through more (N) cascade-connected rectifiers. The advantages of this solution with respect to the conventional three-phase topology are highlighted along with their dependence on the number (N) of the alternator windings. For this purpose, test results are reported and discussed on a prototype generator whose stator coils can be differently connected to obtained one, two, three or four windings. The major benefits (in terms of DC output current quality and field current ripple) are found when passing from the three-phase solution to the dual winding topology; conversely, relatively little advantage is gained by increasing the number of stator windings above two.展开更多
A microgrid is a combination of distributed energy resources and controllable loads. The main objective of this research is to optimize energy flow within a microgrid with regards to reliability in grid connected mode...A microgrid is a combination of distributed energy resources and controllable loads. The main objective of this research is to optimize energy flow within a microgrid with regards to reliability in grid connected mode. A microgrid with combined heat and power, natural gas generator, diesel generator, solar energy, wind energy, and battery energy storage along with a critical load is considered in this research. An event oriented analytical method called FTA (fault trees analysis) is implemented for reliability optimization using PTC Windchill Solutions software in a microgrid. The reliability of each component in each energy source of the microgrid is calculated using FTA. The reliability of the critical load is evaluated. The quantitative and qualitative results of FTA are evaluated in order to interpret the results of fault tree. The sensitivity and uncertainty of the fault tree results for critical load is deduced by calculating the importance measures such as risk achievement worth, risk reduction worth, criticality importance and Fussel-Vesely importance. Finally from the results the components that are sensitive and at high risk are deduced.展开更多
This paper presents the outdoor performance evaluation of different grid-connected PV technologies installed in Cyprus over a two year period. The PV research and testing facility at the University of Cyprus was commi...This paper presents the outdoor performance evaluation of different grid-connected PV technologies installed in Cyprus over a two year period. The PV research and testing facility at the University of Cyprus was commissioned in 2006 to perform continuous measurements of meteorological and PV operational parameters. The test site is appropriately equipped to undertake such evaluations at a very high resolution (1 measurement per second). The perfromance results obtained for the two year evaluation period clearly show how each PV technology has performed under the climatological conditions in Cyprus. Finally the high average energy yield of the fixed plate systems under test, 1580 kWh/kWp and 1609 kWh/kWp during the first and second year of evaluation respectively, also verifies that solar energy is a very promising renewable source of energy for countries with a high solar resource.展开更多
文摘Aim: To compare the contents of nucleosides from natural Cordyceps sinensis and cultured Cordyceps mycelia, and to study the effect of humidity and heat on the content of nucleosides. Methods: The contents of nucleosides were determined by using high performance capillary electrophoresis (HPCE). Beckman P/ACE System 5010 apparatus equipped with a UV detector and a Beckman untreated fused-silica capillary (57 cm 75 mm, 50 cm effective length) was used. Before sample injection, the capillary was rinsed with 1 molL-1 sodium hydroxide solution and running buffer for 5 min, respectively. A voltage of 20 kV was applied for the separation. Pressure injection was 586 kPa for 6 seconds, and the wavelength of detector was 254 nm. The running time was 20 min at 20 oC. The effect of humidity and heat on the contents of nucleosides from natural Cordyceps sinensis and cultured Cordyceps mycelia was observed for 1, 3, 5 and 10 days at temperature 40 oC, and relative humidity 75%. Results: The content of nucleosides from natural Cordyceps sinensis was higher than that from cultured Cordyceps mycelia. But the contents of nucleosides from freshly collected natural Cordyceps sinensis were very low, even below the limit of quantitation. The contents of nucleosides from natural Cordyceps sinensis were significantly increased by humidity and heat, but this phenomenon was not observed in cultured Cordyceps mycelia. Conclusion: There are differences between the nucleosides from natural Cordyceps sinensis and cultured Cordyceps mycelia. The nucleosides in natural Cordyceps sinensis may be derived from the degradation of nucleic acids. This implies that adenosine being used for the quality control of natural Cordyceps sinensis may have to be reconsidered.
基金supported by the Implementation Programs for Marine Renewable Energy Special Funds (GHME2012ZC02)
文摘Actual sea condition testing and inspection and evaluation method research are carried out for tidal energy devices to provide scientific and effective technical support for the ocean high-tech achievement transformation and marine renewable energy development. By analyzing three core indicators, including the power output characteristics of the tidal current device, the generating capacity, energy conversion efficiency, proposed the test contents and evaluation methods of indicators are proposed in this paper; and based on the research of wind farms, power quality testing and assessment methods of offshore tidal energy device are proposed; given the security access to the test contents of tidal current energy device, tidal current energy device running conditions in the testing ground are comprehensively assessed.
文摘AIM: To evaluated the value of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) scan in diagnosis of hepatocellular carcinoma (HCC) and extrahepatic metastases. METHODS: A total of 138 patients with HCC who had both conventional imaging modalities and 18F-FDG PET/CT scan done between November 2006 and March 2011 were enrolled. Diagnostic value of each imaging modality for detection of extrahepatic metastases was evaluated. Clinical factors and tumor characteristics including PET imaging were analyzed as indicative factors for metastases by univariate and multivariate methods. RESULTS: The accuracy of chest CT was significantly superior compared with the accuracy of PET imaging for detecting lung metastases. The detection rate of metastatic pulmonary nodule ≥ 1 cm was 12/13 (92.3%), when < 1 cm was 2/10 (20%) in PET imaging. The accuracy of PET imaging was significantly superior compared with the accuracy of bone scan for detecting bone metastases. In multivariate analy- sis, increased tumor size (≥ 5 cm) (P = 0.042) and increased average standardized uptake value (SUV) uptake (P = 0.028) were predictive factors for extrahepatic metastases. Isometabolic HCC in PET imaging was inversely correlated in multivariate analysis (P = 0.035). According to the receiver operating characteristic curve, the optimal cutoff of average SUV to predict extrahepatic metastases was 3.4. CONCLUSION: 18F-FDG PET/CT scan is invaluable for detection of lung metastases larger than 1 cm and bone metastases. Primary HCC having larger than 5 cm and increased average SUV uptake more than 3.4 should be considered for extrahepatic metastases.
文摘Energy-conservation based generation dispatching is the revolutionary change in operation mode which could reduce energy consumption and pollutant emissions, promote power industry restructuring, and achieve sustainable development. Social benefit evaluation of the energy-conservation based generation dispatching under the new situation and environment has come into being as an important theoretical issue. A new scenario analysis based social benefit evluating method, which is implemented by comparing the energy., consumption and pollutant emissions of different scenarios defined by the key indicators, i.e., load factor and coal consumption structure, is proposed in the paper. Then the composition of social benefit is analyzed from the point of the dispatching mode and the coal consumption structure. The method proposed is of clear physical meaning. It is not only practical, but also applicable for the implementation of energy-conservation based generation dispatching in diffferent phases and with different goals.
基金National Natural Science Foundation of China(No.519667013)Institution of Higher Learning Scientific Research Project of Gansu Province of China(No.2016B-032)。
文摘Considering comprehensive benefit of micro-grid system and consumers,we establish a mathematical model with the goal of the maximum consumer satisfaction and the maximum benefit of power generation side in the view of energy management.An improved multi-objective local mutation adaptive quantum particle swarm optimization(MO-LM-AQPSO)algorithm is adopted to obtain the Pareto frontier of consumer satisfaction and the benefit of power generation side.The optimal solution of the non-dominant solution is selected with introducing the power shortage and power loss to maximize the benefit of power generation side,and its reasonableness is verified by numerical simulation.Then,translational load and time-of-use electricity price incentive mechanism are considered and reasonable peak-valley price ratio is adopted to guide users to actively participate in demand response.The simulation results show that the reasonable incentive mechanism increases the benefit of power generation side and improves the consumer satisfaction.Also the mechanism maximizes the utilization of renewable energy and effectively reduces the operation cost of the battery.
文摘In this paper, the generator set of R 〈 x1,x2 〉G is obtained in according to the group G = Gl(n,R). The conditions of G = Gl(n, R) -equivalence of a pair of curves are found in terms of G = Gl(n, R)-invariants. And the independence of GL(n, R) -invariants is shown.
文摘This article analyzes the importance of the moderately leading development in electric power industry, and the basic policy of the industry in China. It evaluates if the industry is appropriately developed ahead of other industries from the aspects of legal structuring, planning, electricity pricing mechanism, fixed assets investment, human resources, technological innovation and production and supply capacity etc., and proposes f ive recommendations.
文摘The main objective of this study is estimating environmental pollution of hybrid biomass and co-generation power plants. Efficiency of direct tapping of biomass is about 15%-20%. Consequently, about 80% of energy would be waste in this method. While in co-generation power plant, this number could improve to more than 50%. Therefore, to achieve higher efficiency in utilizing biomass energy, co-generation power plants is proposed by using biogas as fuel instead of natural gas. Proposed system would be supplied thermal and electrical energy for non-urban areas of Iran. In this regard, process of fermentation and gas production from biomass in a vertical digester is studied and simulated using analytic methods. Various factors affecting the fermentation, such as temperature, humidity, PH and optimal conditions for the extraction of gas from waste agriculture and animal are also determined. Comparing between the pollution emission from fossil fuel power plants and power plants fed by biomass shows about 88% reduction in greenhouse emission which significant number.
文摘This research seeks to evaluate the economic benefits to be gained by installing a small-scale wind turbine for a customer with a three-phase electrical supply requirement. The evidence for the claims made in this paper is obtained by using actual data obtained from the installed equipment over a three year period. The objective is to accurately appraise the financial investment using real data. There appears to be limited studies conducted into this type of research, possibly because the renewable energy sector is in the infancy stage in the host country, Ireland. There are some wind energy installations with financial appraisal techniques based on modeled data, which may, or may not, be accurate. The study concludes by claiming that the financial benefits of the wind energy turbine installation had disappointing results when compared to predicted benefits based on modeled data.
文摘Nowadays IPP's power plant construction is encouraged by the current deregulatory climate. The financing technique employed to implement these projects is often the project financing formula. Under such condition an investor consortium, usually foreigner plan, build, operate the power plant and sell the generated electricity to the host utility. The sale price is determined from the expected IPP's production cost, enhanced from the expected welfare obtainable by selling electricity. This paper proposes a methodology for linking the uncertainty of the future production cost with the price of the electricity generated by an IPP. This is a stochastic approach to the sale price definition problem, while usually conducted through a deterministic procedure.
文摘The global energy related challenges, mainly due to the worldwide growing energy consumption gone with a reduction ofoil and gas availability, is leading to an increasing interest on hydrogen as energy carrier. Molten salts at temperatures up to 550 ~C can be used as solar heat carrier and storage system, and hydrogen selective membranes can be used to drive reforming reaction at lower temperatures than conventional (〈 550 ~C), with hydrogen purification achieved thereby. The combination of new technologies such as membranes and membrane reactors, concentrating solar power (CSP) systems and molten salt heat carriers, allows a partial decarbonation of the fossil fuel together with the possibility to carry solar energy in the current natural gas grid. The aim of this work is to present a life cycle assessment of a novel hybrid plant for the production of a mixture of methane and hydrogen, called enriched methane, from a steam reforming reactor whose heat duty is supplied by a molten salt stream heated up by an innovative concentrating solar power (CSP) plant developed by ENEA. The performance of this plant will be evaluated from an environmental point of view by the use of an LCA software (SimaPro7) and compared with the ones of traditional plants (reformer and cracker for the hydrogen production) for the production of enriched methane.
文摘China has a large potential to reduce CO2 emission in the Asian region. In this study, life cycle analyses of energy supply technologies in China were evaluated for enforcing the clean development mechanism (CDM). Wind power, integrated coal gasification combined cycle (IGCC), natural gas combined cycle (NGCC), and ultra super critical power plant (USC) were chosen as new power generation technologies. The system function of the developed model was enhanced to extend coverage to new technologies for power generation systems in China. CO2 intensities, energy profit ratios, and CO2 emission reductions are estimated based on the assumption that these power plants were constructed at Shanxi, Xinjiang, and Shanghai. Wind power showed the best results with regard to CO2 intensity and energy profit ratio. However, it also has some disadvantages with regard to the utilization factor and the lifetime. It is considered that wind power will become an important part of CDM activities as the utilization factor and the lifetime improve. An NGCC using a natural gas pipeline was found to be most advantageous in reducing CO2 emission. IGCC and USC were inferior to NGCC with regard to energy profit ratios and CO2 emission reductions.
文摘At Olkaria (Kenya) geothermal energy has been used since 1981, to generate electricity and now there are currently 3 plants with a nominal capacity of 205 MW. Preliminary measurement and evaluation of possible mercury (Hg) emission from two plants has been investigated. Potential atmospheric Hg emission has been determined based on an existing model for estimating the transport of mercury along geothermal fluid flow streams as pertains to energy recovery and conversion from liquid dominated geothermal reservoirs. Hg concentrations, addition, retention and release rates were calculated at a number of locations in the geothermal power plants based on the plant operating parameters and steam flow process (turbine, condenser, non-condensable gas ejector, and cooling tower). Potential Hg emission rates through plume range from 0.455 g/h to 2.17 g/h, or 10-30 mg/h per MWe. The emission per hour per MWe is 130-300 times lower compared to Hg levels reported for 88 MWe five operating geothermal power plants around Mt. Amiata area in Italy. These emissions are coupled with a release of 1.07 kg/h per MW of hydrogen sulphide (HzS). The potential Hg release rates to the environment will depend greatly on the concentration of HzS in the system. Any higher HzS contents may reduce solubility of rig in the brine hence making it to be available in the steam. The volatile Hg may travel with the non-condensable gases as Hg vapour.
文摘Firstly, the construction background and basic connotations of CNOOC's Green Supply Chain was presented in this paper. Then, a detailed introduction to CNOOC's good practices for building green oil and gas fields, green power plants, green refineries and green chemical plants was given with respect to the establishment of a green production construction and assessment system as well as green exploration, green manufacturing,green products, green sales, green recovery and other aspects. Finally, the effects of the Green Supply Chain established by CNOOC were summarized.
基金National Natural Science Foundation of China (No.10571025)Key Project of Chinese Ministry of Education (No.106076)
文摘In this paper,through applying the result of backward stochastic differential equations,it investigates a domination for pricing of the contingent claims by the use of nonlinear infinitesimal generator of process X. This domination provides a guide for valuing the price of the position on the financial market.
文摘Modern power systems are typically characterized with renewable energies and smart grids.Their developments should be kept at a compatible pace with each other.According to the different structures of the power industry,such as generation,transmission,distribution,consumption and dispatching,a comprehensive evaluation system for coordinated development of renewable energy and smart grid in"3 levels,4 sections,15 targets"is created.The index system of coordinated development is important to determine the priorities and key areas in smart grids and renewable energies.By the index system of coordinated development,this paper evaluates the status of renewable energy and grid development,and their degree of coordination in China.A quantitative evaluation method to determine the level of coordination between China's renewable energies and smart grids is developed.The total and component coordination levels in China are calculated by an analytic hierarchy process.In conclusion,the degree of coordination in transmission and dispatching is higher, but the extent of electricity consumption is lowest.Therefore,the consumption section should be the first to develop within China.
文摘DC distribution networks are often employed in isolated power systems like in marine and aeronautical applications. An interesting alternative to DC machines for the supply of DC grids is constituted by a three-phase alternator feeding an AC/DC rectifier. In this paper, alternative solutions are investigated where the AC alternator is equipped with more (iV) three-phase windings and feeds the DC load through more (N) cascade-connected rectifiers. The advantages of this solution with respect to the conventional three-phase topology are highlighted along with their dependence on the number (N) of the alternator windings. For this purpose, test results are reported and discussed on a prototype generator whose stator coils can be differently connected to obtained one, two, three or four windings. The major benefits (in terms of DC output current quality and field current ripple) are found when passing from the three-phase solution to the dual winding topology; conversely, relatively little advantage is gained by increasing the number of stator windings above two.
文摘A microgrid is a combination of distributed energy resources and controllable loads. The main objective of this research is to optimize energy flow within a microgrid with regards to reliability in grid connected mode. A microgrid with combined heat and power, natural gas generator, diesel generator, solar energy, wind energy, and battery energy storage along with a critical load is considered in this research. An event oriented analytical method called FTA (fault trees analysis) is implemented for reliability optimization using PTC Windchill Solutions software in a microgrid. The reliability of each component in each energy source of the microgrid is calculated using FTA. The reliability of the critical load is evaluated. The quantitative and qualitative results of FTA are evaluated in order to interpret the results of fault tree. The sensitivity and uncertainty of the fault tree results for critical load is deduced by calculating the importance measures such as risk achievement worth, risk reduction worth, criticality importance and Fussel-Vesely importance. Finally from the results the components that are sensitive and at high risk are deduced.
文摘This paper presents the outdoor performance evaluation of different grid-connected PV technologies installed in Cyprus over a two year period. The PV research and testing facility at the University of Cyprus was commissioned in 2006 to perform continuous measurements of meteorological and PV operational parameters. The test site is appropriately equipped to undertake such evaluations at a very high resolution (1 measurement per second). The perfromance results obtained for the two year evaluation period clearly show how each PV technology has performed under the climatological conditions in Cyprus. Finally the high average energy yield of the fixed plate systems under test, 1580 kWh/kWp and 1609 kWh/kWp during the first and second year of evaluation respectively, also verifies that solar energy is a very promising renewable source of energy for countries with a high solar resource.