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CO2 Emissions (co2 + emission)
Selected AbstractsTHE FUTURE TRAJECTORY OF U.S. CO2 EMISSIONS: THE ROLE OF STATE VS.JOURNAL OF REGIONAL SCIENCE, Issue 1 2007AGGREGATE INFORMATION ABSTRACT This paper provides comparisons of a variety of time-series methods for short-run forecasts of the main greenhouse gas, carbon dioxide, for the United States, using a recently released state-level data set from 1960,2001. We test the out-of-sample performance of univariate and multivariate forecasting models by aggregating state-level forecasts versus forecasting the aggregate directly. We find evidence that forecasting the disaggregate series and accounting for spatial effects drastically improves forecasting performance under root mean squared forecast error loss. Based on the in-sample observations we attempt to explain the emergence of voluntary efforts by states to reduce greenhouse gas emissions. We find evidence that states with decreasing per capita emissions and a "greener" median voter are more likely to push toward voluntary cutbacks in emissions. [source] How Uncertain Are Estimates of CO2 Emissions?JOURNAL OF INDUSTRIAL ECOLOGY, Issue 1 2009Gregg Marland First page of article [source] Cycle analysis of low and high H2 utilization SOFCs/gas turbine combined cycle for CO2 recoveryELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 10 2008Takuya Taniuchi Abstract Global warming is mainly caused by CO2 emission from thermal power plants, which burn fossil fuel with air. One of the countermeasure technologies to prevent global warming is CO2 recovery from combustion flue gas and the sequestration of CO2 underground or in the ocean. SOFC and other fuel cells can produce high-concentration CO2, because the reformed fuel gas reacts with oxygen electrochemically without being mixed with air, or diluted by N2. Thus, we propose to operate the multistage SOFCs under high utilization of reformed fuel for obtaining high-concentration CO2. In this report, we have estimated the multistage SOFCs' performance considering H2 diffusion and the combined cycle efficiency of multistage SOFC/gas turbine/CO2 recovery power plant. The power generation efficiency of our CO2 recovery combined cycle is 68.5% and the efficiency of conventional SOFC/GT cycle is 57.8% including the CO2 recovery amine process. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 91(10): 38,45, 2008; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/ecj.10165 [source] A diffusion model with cubic drift: statistical and computational aspects and application to modelling of the global CO2 emission in SpainENVIRONMETRICS, Issue 1 2007R. Gutiérrez Abstract The aim of this work is the study of a new stochastic diffusion model with a cubic-type drift coefficient. The model is considered as the solution of an Ito stochastic differential equation. Using the Ito's stochastic calculus and properties of the Kummer function, the trend functions and steady-state distribution for the process are obtained. Statistical estimation and corresponding computational methodology are established. Finally, the model is applied to modelling and prediction of the global CO2 emission in Spain. Copyright © 2006 John Wiley & Sons, Ltd. [source] Soil-atmospheric exchange of CO2, CH4, and N2O in three subtropical forest ecosystems in southern ChinaGLOBAL CHANGE BIOLOGY, Issue 3 2006XULI TANG Abstract The magnitude, temporal, and spatial patterns of soil-atmospheric greenhouse gas (hereafter referred to as GHG) exchanges in forests near the Tropic of Cancer are still highly uncertain. To contribute towards an improvement of actual estimates, soil-atmospheric CO2, CH4, and N2O fluxes were measured in three successional subtropical forests at the Dinghushan Nature Reserve (hereafter referred to as DNR) in southern China. Soils in DNR forests behaved as N2O sources and CH4 sinks. Annual mean CO2, N2O, and CH4 fluxes (mean±SD) were 7.7±4.6 Mg CO2 -C ha,1 yr,1, 3.2±1.2 kg N2O-N ha,1 yr,1, and 3.4±0.9 kg CH4 -C ha,1 yr,1, respectively. The climate was warm and wet from April through September 2003 (the hot-humid season) and became cool and dry from October 2003 through March 2004 (the cool-dry season). The seasonality of soil CO2 emission coincided with the seasonal climate pattern, with high CO2 emission rates in the hot-humid season and low rates in the cool-dry season. In contrast, seasonal patterns of CH4 and N2O fluxes were not clear, although higher CH4 uptake rates were often observed in the cool-dry season and higher N2O emission rates were often observed in the hot-humid season. GHG fluxes measured at these three sites showed a clear increasing trend with the progressive succession. If this trend is representative at the regional scale, CO2 and N2O emissions and CH4 uptake in southern China may increase in the future in light of the projected change in forest age structure. Removal of surface litter reduced soil CO2 effluxes by 17,44% in the three forests but had no significant effect on CH4 absorption and N2O emission rates. This suggests that microbial CH4 uptake and N2O production was mainly related to the mineral soil rather than in the surface litter layer. [source] Role of lakes for organic carbon cycling in the boreal zoneGLOBAL CHANGE BIOLOGY, Issue 1 2004Grete Algesten Abstract We calculated the carbon loss (mineralization plus sedimentation) and net CO2 escape to the atmosphere for 79 536 lakes and total running water in 21 major Scandinavian catchments (size range 437,48 263 km2). Between 30% and 80% of the total organic carbon that entered the freshwater ecosystems was lost in lakes. Mineralization in lakes and subsequent CO2 emission to the atmosphere was by far the most important carbon loss process. The withdrawal capacity of lakes on the catchment scale was closely correlated to the mean residence time of surface water in the catchment, and to some extent to the annual mean temperature represented by latitude. This result implies that variation of the hydrology can be a more important determinant of CO2 emission from lakes than temperature fluctuations. Mineralization of terrestrially derived organic carbon in lakes is an important regulator of organic carbon export to the sea and may affect the net exchange of CO2 between the atmosphere and the boreal landscape. [source] Environmentally-friendly Aspects and Innovative Lightweight Traction System Technologies of the Shinkansen High-speed EMUsIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 2 2008Yoshiyasu Hagiwara Member Abstract In 1964, the Tokaido Shinkansen marked the start of the world's first commercial service high-speed railway that operates at over 200 km/h. Since then, the Tokaido Shinkansen has demonstrated successful business and technological advancement. With the speeding-up of the Shinkansen, environmental matters such as noise and vibration have become critical issues. Measures taken to counter noise and vibration,such as weight reduction and aerodynamics,also effect global environmental measures to reduce energy consumption and CO2 emission. With the introduction of the Series 300, there was a system change of applying an AC drive system, and the lightweight body realized performance improvement over the earlier Series 0. The high-speed EMUs have readily taken advantage of technological innovation such as those achieved in electronics technology. In particular, an innovative AC drive system comprising a power converter with a GTO thyristor and asynchronous motors realized a high-performance and lightweight traction system for high-speed EMUs in the 1990s. Furthermore, recent innovations in electronics technology, such as low switching loss power devices and high-power permanent magnets, have improved the AC drive systems of the high-speed EMUs of the 21st century. This article starts out by introducing environmentally friendliness of the Shinkansen trains in terms of low energy consumption by means of traction system change, and then proceeds to describe the recent technological innovations that have given birth to lightweight traction systems, such as the Permanent Magnet Synchronous traction Motor (PMSM) and power converters with train-draft-cooling systems. The article concludes by summing up the environmentally friendly aspects of the Tokaido Shinkansen. Copyright © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] Optimization of parabolic trough solar collector systemINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 4 2006Saad D. Odeh Abstract Process heat produced by solar collectors can contribute significantly in the conservation of conventional energy resources, reducing CO2 emission, and delaying global warming. One of the major problems associated with solar process heat application is fluctuation in system temperature during unsteady state radiation conditions which may cause significant thermal and operation problems. In this paper a transient simulation model is developed for analysing the performance of industrial water heating systems using parabolic trough solar collectors. The results showed that to prevent dramatic change and instability in process heat during transient radiation periods thermal storage tank size should not be lower than 14.5 l m,2 of collector area. Small periods of radiation instability lower than 30 min do not have significant effect on system operation. During these periods when water flow rate of collector loop is doubled the time required to restore system normal operating condition increased by a ratio of 1.5. Copyright © 2005 John Wiley & Sons, Ltd. [source] Refrigerated transport and environmentINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 10 2004S. K. Chatzidakis Abstract The regulations and the technical specifications for international carriage of perishable foodstuffs and for the special equipment to be used for such carriage are prescribed in the international ATP Agreement. The refrigerated special equipment has to be checked for quality conformity with the ATP standards, at officially designated national ATP test stations. Some of the alternatively proposed ATP testing procedures for checking of the in-service and second-hand refrigerated transport equipment are incomplete and can give incorrect test results. The consequence is increase in energy consumption and an increased environmental pollution through CO2 emission. This study analyses the ATP testing procedures for in-service equipment, investigates the impact on the environmental and gives some proposals for improvement. Copyright © 2004 John Wiley & Sons, Ltd. [source] Lack of discontinuous gas exchange in a tracheate arthropod, Leiobunum townsendi (Arachnida, Opiliones)PHYSIOLOGICAL ENTOMOLOGY, Issue 2 2002John R. B. Lighton Abstract The discontinuous gas exchange cycle, characterized by stringent spiracular control and periods of near-zero external CO2 emission separated by ,bursts' of CO2 emission, has evolved independently in several taxa of tracheate arthropods. These include the hexapoda, diplopoda, and several arachnid taxa; ticks, pseudoscorpions and solphugids. This paper presents the first data on gas exchange kinetics in a harvestman (Arachnida; Opiliones). The experimental animal, Leiobunum townsendi Weed, from an arid area of the south-western United States, displayed a metabolic rate similar to those of other arthropods at 25 °C (129 ± 22 µW). Their CO2 emission kinetics showed, when the animals were motionless, only minor variations about a mean value of 0.0217 ± 0.0037 mL/h (n = 6, mean body mass 86 mg). Expressed on an intra-recording basis, the coefficient of variation of CO2 emission (= SD/MEAN), which is an index of short-term gas emission fluctuations and thus of spiracular control, had a mean value of only 0.082. In contrast, the coefficient of variation of animals employing a discontinuous gas exchange cycle is >,1.5. Gas exchange in opilionids, unlike the case with most other tracheate arthropods, may therefore be dominated by simple diffusion without a prominent role for wide modulations of spiracular conductance. Contributory to this conservative spiracular control strategy may be the weak degree of tracheation in opilionids, combined with circulating haemocyanin, which acts as both a transport medium and a buffering reservoir for respiratory gas exchange. [source] An environmental evaluation of household garbage processorsELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 7 2010Kazuhito Haruki Abstract The amount of garbage emitted from households and industries has been constantly increasing in recent years, and its treatment cost has been a financial burden to municipal governments in Japan. Many municipal governments recommend that their citizens purchase household garbage processors in order to reduce the volume of garbage transferred to and incinerated at their facilities. Actually, 1535 municipal governments subsidize their citizens' purchase of electrical garbage processors and/or compost containers. These subsidies should be assessed from various points of view, such as the costs and benefits to municipal governments and citizens, and also global or local environmental loads. An environmental planning department of a city office sent questionnaires to its residents to investigate the utilization of the subsidized devices. An environmental organization of citizens supported the department with design of the questionnaire form and analysis of the collected questionnaire data. In this paper, the processes of designing the form and analyzing the data are explained, and then an evaluation of the subsidy is presented. The conclusions are as follows: Electrical garbage processors would be beneficial for dealing with local environmental problems such as lack of a final landfill site. However, the processors will increase CO2 emissions unless their electrical consumption efficiency can be improved. © 2010 Wiley Periodicals, Inc. Electron Comm Jpn, 93(7): 42,52, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10285 [source] Profile of the climate change in the Kingdom of BahrainENVIRONMETRICS, Issue 8 2003W. E. Alnaser Abstract Long-term meteorological data from the Kingdom of Bahrain (1902 to 2001), along with other data from the Sultanate of Oman and the Kingdom of Saudi Arabia, were used to study the profile and the characteristics of the climate changes in the Kingdom of Bahrain. This article illustrates the possible effects of several factors, such as greenhouse gases (GHG), sunspot number, cosmic ray flux, planet conjunctions, the Earth's magnetic field, as well as volcanic eruption, on the profile of the climate change. In general, we found that the temperature variations, to a certain extent, are associated with the cyclic variations in sunspot number (the 11-year cycle), which in turn affect the pattern of the cosmic ray flux due to the distortion of the interplanetary magnetic field. The latter is believed to influence cloud formation. In addition, the discrepancy in the climate change pattern in Bahrain was also attributed to the combined effect of the high local level of CO2 emissions as well as that of other cooling gases in the region. Copyright © 2003 John Wiley & Sons, Ltd. [source] Translocation of soils to stimulate climate change: CO2 emissions and modifications to soil organic matterEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 6 2007M. Rey Summary The effect of climate change on CO2 emissions was studied on undisturbed soil monoliths (40-cm diameter, 25-cm high), which were translocated to warmer zones than their place of origin. Thirty-two months after the translocation, a climatic factor deduced from the moisture content of the soil and from the effective mean temperature (temperatures in excess of 5°C) revealed that translocation increased the potential of the climate to enhance the biological processes by between 73% and 26% compared with what the soil would support in its place of origin. At the end of the study, the transported soils had lost a large proportion of both total carbon and nitrogen (between 20 and 45%). During the experiment, the CO2 emissions from the soils, measured under field conditions, were quite variable, but were usually greater than from soils in situ. The variation in labile C in the soil throughout the experiment was calculated from a first-order kinetic equation for organic matter decay. The relative CO2 emissions, expressed in terms of the labile carbon fraction in the soils, were clearly greater in those translocated soils that underwent the most intensive climate change, which indicates that the variations in emissions over time are basically a function of the size of the labile organic matter pool. [source] Emissions of N2O from soils during cycles of freezing and thawing and the effects of soil water, texture and duration of freezingEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2004R. Teepe Summary Freezing and thawing influence many physical, chemical and biological processes in soils, including the production of trace gases. We studied the effects of freezing and thawing on three soils, one sandy, one silty and one loamy, on the emissions of N2O and CO2. We also studied the effect of varying the water content, expressed as the percentage of the water-filled pore space (WFPS). Emissions of N2O during thawing decreased in the order 64% > 55% > 42% WFPS, which suggests that the retardation of the denitrification was more pronounced than the acceleration of the nitrification with increasing oxygen concentration in the soil. However, emissions of N2O at 76% WFPS were less than at 55% WFPS, which might be caused by an increased ratio of N2/N2O in the very moist conditions. The emission of CO2 was related to the soil water, with the smallest emissions at 76% WFPS and largest at 42% WFPS. The emissions of CO2 during thawing exceeded the initial CO2 emissions before the soils were frozen, which suggests that the supply of nutrients was increased by freezing. Differences in soil texture had no marked effect on the N2O emissions during thawing. The duration of freezing, however, did affect the emissions from all three soils. Freezing the soil for less than 1 day had negligible effects, but freezing for longer caused concomitant increases in emissions. Evidently the duration of freezing and soil water content have important effects on the emission of N2O, whereas the effects of texture in the range we studied were small. [source] Carbon sequestration under Miscanthus: a study of 13C distribution in soil aggregatesGCB BIOENERGY, Issue 5 2009MARTA DONDINI Abstract The growing of bioenergy crops has been widely suggested as a key strategy in mitigating anthropogenic CO2 emissions. However, the full mitigation potential of these crops cannot be assessed without taking into account their effect on soil carbon (C) dynamics. Therefore, we analyzed the C dynamics through four soil depths under a 14-year-old Miscanthus plantation, established on former arable land. An adjacent arable field was used as a reference site. Combining soil organic matter (SOM) fractionation with 13C natural abundance analyses, we were able to trace the fate of Miscanthus -derived C in various physically protected soil fractions. Integrated through the whole soil profile, the total amount of soil organic carbon (SOC) was higher under Miscanthus than under arable crop, this difference was largely due to the input of new C. The C stock of the macroaggregates (M) under Miscanthus was significantly higher than those in the arable land. Additionally, the C content of the micro-within macroaggregates (mM) were higher in the Miscanthus soil as compared with the arable soil. Analysis of the intramicroaggregates particulate organic matter (POM) suggested that the increase C storage in mM under Miscanthus was caused by a decrease in disturbance of M. Thus, the difference in C content between the two land use systems is largely caused by soil C storage in physically protected SOM fractions. We conclude that when Miscanthus is planted on former arable land, the resulting increase in soil C storage contributes considerably to its CO2 mitigation potential. [source] Algorithm for determining optimum sequestration depth of CO2 trapped by residual gas and solubility trapping mechanisms in a deep saline formationGEOFLUIDS (ELECTRONIC), Issue 4 2008C. K. LIN Abstract An algorithm is proposed here for determining the optimum sequestration depth (in terms of depth corresponding to maximum net income per unit rock volume) in a saline formation for CO2 trapped by residual gas and solubility trapping mechanisms. The Peng,Robinson equation of state was used to determine the density and fugacity of sequestered CO2 and the compression energy required for CO2 injection. Geochemist's Workbench®, a commercial geochemical software package, was used to estimate CO2 solubility in groundwater. Operational costs and CO2 emissions due to compression energy consumption were estimated. A hypothetical reference case was constructed to illustrate the proposed algorithm, assuming constant values of geothermal gradient, hydrostatic pressure gradient, sweep efficiency and initial groundwater chemistry, with a depth-dependent porosity and porosity-dependent saturation of residual gas. In general, the algorithm was illustrated successfully for the hypothetical reference case and produced the following results. The depth corresponding to maximum trapping capacity was approximately 3000 m, but the depth representing maximum net income was approximately 1300 m. CO2 emissions due to compression energy consumption per unit mass of CO2 sequestration cannot be ignored, but may be <0.15, even down to a depth of 7000 m. Both the trapping capacity and net income of CO2 sequestration decreased with geothermal gradient, but the corresponding optimum depths increased with geothermal gradient. [source] Litter decomposition in grasslands of Central North America (US Great Plains)GLOBAL CHANGE BIOLOGY, Issue 5 2009ELIANA E. BONTTI Abstract One of the major concerns about global warming is the potential for an increase in decomposition and soil respiration rates, increasing CO2 emissions and creating a positive feedback between global warming and soil respiration. This is particularly important in ecosystems with large belowground biomass, such as grasslands where over 90% of the carbon is allocated belowground. A better understanding of the relative influence of climate and litter quality on litter decomposition is needed to predict these changes accurately in grasslands. The Long-Term Intersite Decomposition Experiment Team (LIDET) dataset was used to evaluate the influence of climatic variables (temperature, precipitation, actual evapotranspiration, and climate decomposition index), and litter quality (lignin content, carbon : nitrogen, and lignin : nitrogen ratios) on leaf and root decomposition in the US Great Plains. Wooden dowels were used to provide a homogeneous litter quality to evaluate the relative importance of above and belowground environments on decomposition. Contrary to expectations, temperature did not explain variation in root and leaf decomposition, whereas precipitation partially explained variation in root decomposition. Percent lignin was the best predictor of leaf and root decomposition. It also explained most variation in root decomposition in models which combined litter quality and climatic variables. Despite the lack of relationship between temperature and root decomposition, temperature could indirectly affect root decomposition through decreased litter quality and increased water deficits. These results suggest that carbon flux from root decomposition in grasslands would increase, as result of increasing temperature, only if precipitation is not limiting. However, where precipitation is limiting, increased temperature would decrease root decomposition, thus likely increasing carbon storage in grasslands. Under homogeneous litter quality, belowground decomposition was faster than aboveground and was best predicted by mean annual precipitation, which also suggests that the high moisture in soil accelerates decomposition belowground. [source] Partitioning sources of soil respiration in boreal black spruce forest using radiocarbonGLOBAL CHANGE BIOLOGY, Issue 2 2006Edward A.G. Schuur Abstract Separating ecosystem and soil respiration into autotrophic and heterotrophic component sources is necessary for understanding how the net ecosystem exchange of carbon (C) will respond to current and future changes in climate and vegetation. Here, we use an isotope mass balance method based on radiocarbon to partition respiration sources in three mature black spruce forest stands in Alaska. Radiocarbon (,14C) signatures of respired C reflect the age of substrate C and can be used to differentiate source pools within ecosystems. Recently-fixed C that fuels plant or microbial metabolism has ,14C values close to that of current atmospheric CO2, while C respired from litter and soil organic matter decomposition will reflect the longer residence time of C in plant and soil C pools. Contrary to our expectations, the ,14C of C respired by recently excised black spruce roots averaged 14, greater than expected for recently fixed photosynthetic products, indicating that some portion of the C fueling root metabolism was derived from C storage pools with turnover times of at least several years. The ,14C values of C respired by heterotrophs in laboratory incubations of soil organic matter averaged 60, higher than the contemporary atmosphere ,14CO2, indicating that the major contributors to decomposition are derived from a combination of sources consistent with a mean residence time of up to a decade. Comparing autotrophic and heterotrophic ,14C end members with measurements of the ,14C of total soil respiration, we calculated that 47,63% of soil CO2 emissions were derived from heterotrophic respiration across all three sites. Our limited temporal sampling also observed no significant differences in the partitioning of soil respiration in the early season compared with the late season. Future work is needed to address the reasons for high ,14C values in root respiration and issues of whether this method fully captures the contribution of rhizosphere respiration. [source] Role of land cover changes for atmospheric CO2 increase and climate change during the last 150 yearsGLOBAL CHANGE BIOLOGY, Issue 8 2004Victor Brovkin Abstract We assess the role of changing natural (volcanic, aerosol, insolation) and anthropogenic (CO2 emissions, land cover) forcings on the global climate system over the last 150 years using an earth system model of intermediate complexity, CLIMBER-2. We apply several datasets of historical land-use reconstructions: the cropland dataset by Ramankutty & Foley (1999) (R&F), the HYDE land cover dataset of Klein Goldewijk (2001), and the land-use emissions data from Houghton & Hackler (2002). Comparison between the simulated and observed temporal evolution of atmospheric CO2 and ,13CO2 are used to evaluate these datasets. To check model uncertainty, CLIMBER-2 was coupled to the more complex Lund,Potsdam,Jena (LPJ) dynamic global vegetation model. In simulation with R&F dataset, biogeophysical mechanisms due to land cover changes tend to decrease global air temperature by 0.26°C, while biogeochemical mechanisms act to warm the climate by 0.18°C. The net effect on climate is negligible on a global scale, but pronounced over the land in the temperate and high northern latitudes where a cooling due to an increase in land surface albedo offsets the warming due to land-use CO2 emissions. Land cover changes led to estimated increases in atmospheric CO2 of between 22 and 43 ppmv. Over the entire period 1800,2000, simulated ,13CO2 with HYDE compares most favourably with ice core during 1850,1950 and Cape Grim data, indicating preference of earlier land clearance in HYDE over R&F. In relative terms, land cover forcing corresponds to 25,49% of the observed growth in atmospheric CO2. This contribution declined from 36,60% during 1850,1960 to 4,35% during 1960,2000. CLIMBER-2-LPJ simulates the land cover contribution to atmospheric CO2 growth to decrease from 68% during 1900,1960 to 12% in the 1980s. Overall, our simulations show a decline in the relative role of land cover changes for atmospheric CO2 increase during the last 150 years. [source] Urban Polycentricity and the Costs of Commuting: Evidence from Italian Metropolitan AreasGROWTH AND CHANGE, Issue 3 2010PAOLO VENERI ABSTRACT Polycentricity at the metropolitan scale is perhaps the model of spatial organisation that needs to be investigated more thoroughly as regards its effects on travel. The aim of this paper is to test the role of polycentricity,as well as other spatial characteristics, such as compactness, functional diversification and size,in the costs of commuting, taking into account an external cost component (per-capita CO2 emissions) and a private cost component (time spent on travelling). The degree of urban polycentricity has been measured by adopting a dynamic approach based on commuting flows and on social network analysis tools. The analysis is carried out using a database of 82 Italian metropolitan areas (MAs). Results show that MAs with a higher degree of polycentricity are more virtuous both in terms of private and external costs of mobility, while the degree of compactness is associated with lower environmental costs but with higher private costs. Size is associated with both higher external and private costs, while the role of functional diversification turns out to be statistically insignificant. Socio-demographics also play a role. [source] Fixed Energy Storage Technology Applied for DC Electrified RailwayIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 3 2010Takeshi Konishi Member Abstract The fixed energy storage system solves the problem of rising energy costs by reducing primary energy consumption. Without a fixed energy storage system, the energy generated by a braking vehicle would be simply converted into waste heat by its braking resistors if no other vehicles are powered simultaneously. Because, as a rule, such synchronized braking and powering cannot be coordinated, the energy storage system stores the energy generated during braking and discharges it again when a vehicle is powered. This greatly reduces primary energy demand in the substation. However, in addition to this energy saving, the energy storage system contributes to the reduction of CO2 emissions. The energy storage system also stabilizes the system voltage. Recent years have witnessed an advance in the energy storage media technology. Developments of energy storage media, lithium ion battery, nickel-metal hydride battery, and electric double-layer capacitors (EDLCs) have been remarkable. This study introduces technologies of fixed energy storage system applicable for DC electrified railway in Japan, and describes two examples of charge/discharge characteristics. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] Implications of system expansion for the assessment of well-to-wheel CO2 emissions from biomass-based transportationINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 13 2010Elisabeth Wetterlund Abstract In this paper we show the effects of expanding the system when evaluating well-to-wheel (WTW) CO2 emissions for biomass-based transportation, to include the systems surrounding the biomass conversion system. Four different cases are considered: DME via black liquor gasification (BLG), methanol via gasification of solid biomass, lignocellulosic ethanol and electricity from a biomass integrated gasification combined cycle (BIGCC) used in a battery-powered electric vehicle (BPEV). All four cases are considered with as well as without carbon capture and storage (CCS). System expansion is used consistently for all flows. The results are compared with results from a conventional WTW study that only uses system expansion for certain co-product flows. It is shown that when expanding the system, biomass-based transportation does not necessarily contribute to decreased CO2 emissions and the results from this study in general indicate considerably lower CO2 mitigation potential than do the results from the conventional study used for comparison. It is shown that of particular importance are assumptions regarding future biomass use, as by expanding the system, future competition for biomass feedstock can be taken into account by assuming an alternative biomass usage. Assumptions regarding other surrounding systems, such as the transportation and the electricity systems are also shown to be of significance. Of the four studied cases without CCS, BIGCC with the electricity used in a BPEV is the only case that consistently shows a potential for CO2 reduction when alternative use of biomass is considered. Inclusion of CCS is not a guarantee for achieving CO2 reduction, and in general the system effects are equivalent or larger than the effects of CCS. DME from BLG generally shows the highest CO2 emission reduction potential for the biofuel cases. However, neither of these options for biomass-based transportation can alone meet the needs of the transport sector. Therefore, a broader palette of solutions, including different production routes, different fuels and possibly also CCS, will be needed. Copyright © 2009 John Wiley & Sons, Ltd. [source] Effect of supplementary firing options on cycle performance and CO2 emissions of an IGCC power generation systemINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 7 2009N. V. Gnanapragasam Abstract Supplementary firing is adopted in combined-cycle power plants to reheat low-temperature gas turbine exhaust before entering into the heat recovery steam generator. In an effort to identify suitable supplementary firing options in an integrated gasification combined-cycle (IGCC) power plant configuration, so as to use coal effectively, the performance is compared for three different supplementary firing options. The comparison identifies the better of the supplementary firing options based on higher efficiency and work output per unit mass of coal and lower CO2 emissions. The three supplementary firing options with the corresponding fuel used for the supplementary firing are: (i) partial gasification with char, (ii) full gasification with coal and (iii) full gasification with syngas. The performance of the IGCC system with these three options is compared with an option of the IGCC system without supplementary firing. Each supplementary firing option also involves pre-heating of the air entering the gas turbine combustion chamber in the gas cycle and reheating of the low-pressure steam in the steam cycle. The effects on coal consumption and CO2 emissions are analysed by varying the operating conditions such as pressure ratio, gas turbine inlet temperature, air pre-heat and supplementary firing temperature. The results indicate that more work output is produced per unit mass of coal when there is no supplementary firing. Among the supplementary firing options, the full gasification with syngas option produces the highest work output per unit mass of coal, and the partial gasification with char option emits the lowest amount of CO2 per unit mass of coal. Based on the analysis, the most advantageous option for low specific coal consumption and CO2 emissions is the supplementary firing case having full gasification with syngas as the fuel. Copyright © 2008 John Wiley & Sons, Ltd. [source] Influence of advanced injection timing on the performance and emissions of CI engine fueled with ethanol-blended diesel fuelINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 11 2008Cenk Sayin Abstract Ethanol has been considered as an alternative fuel for diesel engines. On the other hand, injection timing is a major parameter that sensitively affects the engine performance and emissions. Therefore, in this study, the influence of advanced injection timing on the engine performance and exhaust emissions of a single cylinder, naturally aspirated, four stroke, direct injection diesel engine has been experimentally investigated when using ethanol-blended diesel fuel from 0 to 15% with an increment of 5%. The original injection timing of the engine is 27° crank angle (CA) before top dead center (BTDC). The tests were conducted at three different injection timings (27, 30 and 33° CA BTDC) for 30 Nm constant load at 1800 rpm. The experimental results showed that brake-specific energy consumption (BSEC), brake-specific fuel consumption (BSFC), NOx and CO2 emissions increased as brake-thermal efficiency (BTE), smoke, CO and HC emissions decreased with increasing amount of ethanol in the fuel mixture. Comparing the results with those of original injection timing, NOx emissions increased and smoke, HC and CO emissions decreased for all test fuels at the advanced injection timings. For BSEC, BSFC and BTE, advanced injection timings gave negative results for all test conditions. Copyright © 2008 John Wiley & Sons, Ltd. [source] Hydrogen utilization as a fuel: hydrogen-blending effects in flame structure and NO emission behaviour of CH4,air flameINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 5 2007Jeong Park Abstract Hydrogen-blending effects in flame structure and NO emission behaviour are numerically studied with detailed chemistry in methane,air counterflow diffusion flames. The composition of fuel is systematically changed from pure methane to the blending fuel of methane,hydrogen through H2 molar addition up to 30%. Flame structure, which can be described representatively as a fuel consumption layer and a H2,CO consumption layer, is shown to be changed considerably in hydrogen-blending methane flames, compared to pure methane flames. The differences are displayed through maximum flame temperature, the overlap of fuel and oxygen, and the behaviours of the production rates of major species. Hydrogen-blending into hydrocarbon fuel can be a promising technology to reduce both the CO and CO2 emissions supposing that NOx emission should be reduced through some technologies in industrial burners. These drastic changes of flame structure affect NO emission behaviour considerably. The changes of thermal NO and prompt NO are also provided according to hydrogen-blending. Importantly contributing reaction steps to prompt NO are addressed in pure methane and hydrogen-blending methane flames. Copyright © 2006 John Wiley & Sons, Ltd. [source] The role of policy instruments for promoting combined heat and power production with low CO2 emissions in district heating systemsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 6 2005Å. Marbe Abstract Policy instruments clearly influence the choice of production technologies and fuels in large energy systems, including district heating networks. Current Swedish policy instruments aim at promoting the use of biofuel in district heating systems, and at promoting electric power generation from renewable energy sources. However, there is increasing pressure to harmonize energy policy instruments within the EU. In addition, natural gas based combined cycle technology has emerged as the technology of choice in the power generation sector in the EU. This study aims at exploring the role of policy instruments for promoting the use of low CO2 emissions fuels in high performance combined heat and power systems in the district heating sector. The paper presents the results of a case study for a Swedish district heating network where new large size natural gas combined cycle (NGCC) combined heat and power (CHP) is being built. Given the aim of current Swedish energy policy, it is assumed that it could be of interest in the future to integrate a biofuel gasifier to the CHP plant and co-fire the gasified biofuel in the gas turbine unit, thereby reducing usage of fossil fuel. The goals of the study are to evaluate which policy instruments promote construction of the planned NGCC CHP unit, the technical performance of an integrated biofuelled pressurized gasifier with or without dryer on plant site, and which combination of policy instruments promote integration of a biofuel gasifier to the planned CHP unit. The power plant simulation program GateCycle was used for plant performance evaluation. The results show that current Swedish energy policy instruments favour investing in the NGCC CHP unit. The corresponding cost of electricity (COE) from the NGCC CHP unit is estimated at 253 SEK MWh,1, which is lower than the reference power price of 284 SEK MWh,1. Investing in the NGCC CHP unit is also shown to be attractive if a CO2 trading system is implemented. If the value of tradable emission permits (TEP) in such as system is 250 SEK tonne,1, COE is 353 SEK MWh,1 compared to the reference power price of 384 SEK MWh,1. It is possible to integrate a pressurized biofuel gasifier to the NGCC CHP plant without any major re-design of the combined cycle provided that the maximum degree of co-firing is limited to 27,38% (energy basis) product gas, depending on the design of the gasifier system. There are many parameters that affect the economic performance of an integrated biofuel gasifier for product gas co-firing of a NGCC CHP plant. The premium value of the co-generated renewable electricity and the value of TEPs are very important parameters. Assuming a future CO2 trading system with a TEP value of 250 SEK tonne,1 and a premium value of renewable electricity of 200 SEK MWh,1 COE from a CHP plant with an integrated biofuelled gasifier could be 336 SEK MWh,1, which is lower than both the reference market electric power price and COE for the plant operating on natural gas alone. Copyright © 2005 John Wiley & Sons, Ltd. [source] A modularized framework for solving an economic,environmental power generation mix problemINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 9 2004Haoxiang Xia Abstract This paper presents a modularized simulation modelling framework for evaluating the impacts on economic cost and CO2 emissions resulting from the introduction of a solid oxide fuel cell (SOFC) system into the existing mix of centralized power generation technologies in Japan. The framework is comprised of three parts: a dual-objective linear programming model that solves the generation best-mix problem for the existing power generation technologies; a nonlinear SOFC system model in which the economic cost and CO2 emissions by the SOFC system can be calculated; and the Queuing Multi-Objective Optimizer (QMOO), a multi-objective evolutionary algorithm (MOEA) developed at the EPFL in Switzerland as the overall optimizer of the combined power supply system. Thus, the framework integrates an evolutionary algorithm that is more suitable for handling nonlinearities with a calculus-based method that is more efficient in solving linear programming problems. Simulation experiments show that the framework is successful in solving the stated problem. Moreover, the three components of the modularized framework can be interconnected through a platform-independent model integration environment. As a result, the framework is flexible and scalable, and can potentially be modified and/or integrated with other models to study more complex problems. Copyright © 2004 John Wiley & Sons, Ltd. [source] The perspectives of energy production from coal-fired power plants in an enlarged EUINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 9 2004P. Grammelis Abstract The aim of this paper is to present the current status of the coal-fired power sector in an enlarged EU (EU-15 plus EU member candidate states) in relation with the main topics of the European Strategy for the energy production and supply. It is estimated that 731 thermoelectric units, larger than 100 MWe, are operating nowadays, and their total installed capacity equals to 200.7 GWe. Coal contribution to the total electricity generation with reference to other fuel sources, is by far more intensive in the non-EU part (EU member candidate states), compared to the EU member states. It is expected that even after the enlargement, the European Union will strongly being related to coal. Enlargement will bring additional factors into play in order to meet the requirements of rising consumption, growing demand for conventional fuels and increasing dependence on imports. Besides the technology, boiler size, efficiency, age and environmental performance will determine the necessities of the coal-fired power sector in each country. Depending on the case, lifetime extension measures in operating coal-fired power plants or clean coal technologies can play an important role towards the energy sector restructuring. Low efficiency values in the non-EU coal-fired units and heavily aged power plants in EU countries will certainly affect decisions in favour of upgrading or reconstruction. The overall increase of efficiency, the reduction of harmful emissions from generating processes and the co-combustion of coal with biomass and wastes for generating purposes indicate that coal can be cleaner and more efficient. Additionally, plenty of rehabilitation projects based on CCT applications, have already been carried out or are under progress in the EU energy sector. The proclamations of the countries' energy policies in the coming decades, includes integrated renovation concepts of the coal-fired power sector. Further to the natural gas penetration in the electricity generation and CO2 sequestration and underground storage, the implementation of CCT projects will strongly contribute to the reduction of CO2 emissions in the European Union, according to the targets set in the Kyoto protocol. In consequence, clean coal technologies can open up new markets not only in the EU member candidate states, but also in other parts of the world. Copyright © 2004 John Wiley & Sons, Ltd. [source] Integrated model framework for the evaluation of an SOFC/GT system as a centralized power sourceINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 1 2004Michihisa Koyama Abstract New power generation technologies are expected to reduce various environmental impacts of providing electricity to urban regions for some investment cost. Determining which power generation technologies are most suitable for meeting the demand of a particular region requires analysis of tradeoffs between costs and environmental impacts. Models simulating different power generation technologies can help quantify these tradeoffs. An Internet-based modelling infrastructure called DOME (distributed object-based modelling environment) provides a flexible mechanism to create integrated models from independent simulation models for different power generation technologies. As new technologies appear, corresponding simulation models can readily be added to the integrated model. DOME was used to combine a simulation model for hybrid SOFC (solid oxide fuel cell) and gas turbine system with a power generation capacity and dispatch optimization model. The integrated models were used to evaluate the effectiveness of the system as a centralized power source for meeting the power demand in Japan. Evaluation results indicate that a hybrid system using micro-tube SOFC may reduce CO2 emissions from power generation in Japan by about 50%. Copyright © 2004 John Wiley & Sons, Ltd. [source] Organic mound-building ants: their impact on soil properties in temperate and boreal forestsJOURNAL OF APPLIED ENTOMOLOGY, Issue 4 2008M. F. Jurgensen Abstract Ants are important components of most soil invertebrate communities, and can affect the flow of energy, nutrients and water through many terrestrial ecosystems. The vast majority of ant species build nests in the mineral soil, but a small group of ants in temperate and boreal forests of Eurasia and North America build large parts of their nests above-ground using organic materials collected from the surrounding soil. Many studies have shown that ants nesting in mineral soil can affect water infiltration rates, soil organic matter (OM) content, and nutrient cycling, but much less is known on how mound-building ants influence soil physical and chemical properties. In this paper we summarize what is known on the soil impacts of organic mound-building ants in temperate and boreal forests, and how these ants could be affected by ecosystem disturbance and future climate change. Much of this information comes from studies on Formica rufa group ants in Europe, which showed that CO2 emissions and concentrations of C, N, and P are usually higher in ant mounds than in the surrounding forest soil. However, ant mounds are a minor component of total soil C and nutrient pools, but they do increase spatial heterogeneity of soil water and available nutrients. Mound-building ants can also impact tree growth, which could change the quantity and quality of OM added to soil. Forest management, fire, and projected climate change, especially in boreal forests, could affect mound-building ant population dynamics, and indirectly, soil properties. [source] | |||||||||||||||||||||||||