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641.
Carbon dioxide capture and storage (CCS) involves the capture of CO2 at a large industrial facility, such as a power plant, and its transport to a geological (or other) storage site where CO2 is sequestered. Previous work has identified pipeline transport of liquid CO2 as the most economical method of transport for large volumes of CO2. However, there is little published work on the economics of CO2 pipeline transport. The objective of this paper is to estimate total cost and the cost per tonne of transporting varying amounts of CO2 over a range of distances for different regions of the continental United States. An engineering-economic model of pipeline CO2 transport is developed for this purpose. The model incorporates a probabilistic analysis capability that can be used to quantify the sensitivity of transport cost to variability and uncertainty in the model input parameters. The results of a case study show a pipeline cost of US$ 1.16 per tonne of CO2 transported for a 100 km pipeline constructed in the Midwest handling 5 million tonnes of CO2 per year (the approximate output of an 800 MW coal-fired power plant with carbon capture). For the same set of assumptions, the cost of transport is US$ 0.39 per tonne lower in the Central US and US$ 0.20 per tonne higher in the Northeast US. Costs are sensitive to the design capacity of the pipeline and the pipeline length. For example, decreasing the design capacity of the Midwest US pipeline to 2 million tonnes per year increases the cost to US$ 2.23 per tonne of CO2 for a 100 km pipeline, and US$ 4.06 per tonne CO2 for a 200 km pipeline. An illustrative probabilistic analysis assigns uncertainty distributions to the pipeline capacity factor, pipeline inlet pressure, capital recovery factor, annual O&M cost, and escalation factors for capital cost components. The result indicates a 90% probability that the cost per tonne of CO2 is between US$ 1.03 and US$ 2.63 per tonne of CO2 transported in the Midwest US. In this case, the transport cost is shown to be most sensitive to the pipeline capacity factor and the capital recovery factor. The analytical model elaborated in this paper can be used to estimate pipeline costs for a broad range of potential CCS projects. It can also be used in conjunction with models producing more detailed estimates for specific projects, which requires substantially more information on site-specific factors affecting pipeline routing. 相似文献
642.
Glenn EP Hucklebridge K Hinojosa-Huerta O Nagler PL Pitt J 《Environmental management》2008,41(3):322-335
Arid zone rivers have highly variable flow rates, and flood control projects are needed to protect adjacent property from
flood damage. On the other hand, riparian corridors provide important wildlife habitat, especially for birds, and riparian
vegetation is adapted to the natural variability in flows on these rivers. While environmental and flood control goals might
appear to be at odds, we show that both goals can be accommodated in the Limitrophe Region (the shared border between the
United States and Mexico) on the Lower Colorado River. In 1999, the International Boundary and Water Commission proposed a
routine maintenance project to clear vegetation and create a pilot channel within the Limitrophe Region to improve flow capacity
and delineate the border. In 2000, however, Minute 306 to the international water treaty was adopted, which calls for consideration
of environmental effects of IBWC actions. We conducted vegetation and bird surveys within the Limitrophe and found that this
river segment is unusually rich in native cottonwood and willow trees, marsh habitat, and resident and migratory birds compared
to flow-regulated segments of river. A flood-frequency analysis showed that the existing levee system can easily contain a
100 year flood even if vegetation is not removed, and the existing braided channel system has greater carrying capacity than
the proposed pilot channel. 相似文献
643.
David L. Fabacher Edward E. Little 《Environmental science and pollution research international》1998,5(1):4-6
Methanol extracts of dorsal skin layers, eyes, gills, and livers from ultraviolet-B (UVB) radiation-sensitive and UVB-tolerant species of freshwater fish were examined for a substance that appears to be photoprotective. Significantly larger amounts of this substance were found in extracts of outer dorsal skin layers from both UVB-sensitive and UVB-tolerant fish when compared with extracts of inner dorsal skin layers. This substance occurred in minor amounts or was not detected in eye, gill, and liver extracts. The apparent primary function of this substance in fish is to protect the cells in outer dorsal skin layers from harmful levels of UVB radiation. 相似文献
644.
This is the first in a series of five articles describing the applicability, performance, and cost of technologies for the remediation of contaminated soil and water at wood preserving sites. Site‐specific treatability studies conducted under the supervision of the United States Environmental Protection Agency (US EPA), National Risk Management Research Laboratory (NRMRL), from 1995 through 1997 constitute much of the basis for the evaluations presented, although data from other treatability studies, literature sources, and actual site remediations have also been included to provide a more comprehensive evaluation of remediation technologies. This article provides an overview of the wood preserving sites studied, including contaminant levels, and a summary of the performance of the technologies evaluated. The subsequent articles discuss the performance of each technology in more detail. Three articles discuss technologies for the treatment of soils, including solidification/stabilization, biological treatment, solvent extraction and soil washing. One article discusses technologies for the treatment of liquids, water and nonaqueous phase liquids (NAPLS), including biological treatment, carbon adsorption, photolytic oxidation, and hydraulic containment. The reader should be aware that other technologies including, but not limited to, incineration, thermal desorption, and base catalyzed dehalogenation, also have application for treating contaminants on wood preserving sites. They are not discussed in these five articles since the focus was to evaluate lesser known and hopefully lower cost approaches. However, the reader should include consideration of these other technologies as part of any evaluation or screening of technologies applicable to remediation of wood preserving sites. 相似文献
645.
This article discusses the use of solidification/stabilization (S/S) to treat soils contaminated with organic and inorganic chemicals at wood preserving sites. Solidification is defined for this article as making a material into a freestanding solid. Stabilization is defined as making the contaminants of concern nonmobile as determined from a leaching test. S/S then combines both properties. For more information on S/S in general the reader should refer to other publications (Connors, J.R. [1990]). Chemical fixation and solidification of hazardous wastes. New York: Van Nostrand Reinhold; US Environmental Protection Agency. [1993a]. Engineering bulletin solidification/stabilization of organics and inorganics (EPA/540/S‐92/015); Wiles, C.C. [1989]. Solidification and stabilization technology. In H.M. Freeman [Ed.], Standard handbook of hazardous waste treatment and disposal. New York: McGraw Hill) as this article addresses only wood preserving sites and assumes basic knowledge of S/S processes. For a more general discussion of wood preserving sites and some other remedial options, the reader may wish to refer to a previous EPA publication (US Environmental Protection Agency. [1992a]. Contaminants and remedial options at wood preserving sites [EPA/600/R‐92/182]). This article includes data from the successful remediation of a site with mixed organic/inorganic contaminants, remediation of a site with organic contaminants, and detailed treatability study results from four sites for which successful formulations were developed. Included are pre‐ and post‐treatment soil characterization data, site vaines. ileizdot‐ names (in some cases), treatment formulas used (generic aridproprietary), costs, recommendations, and citatioiis to inore detailed refer‐ en ces. The data presen ted iiidica te that dioxins, pentachlorophepi 01 (PCP), creosote, polycyclic aromatic hydrocarbom (PAHsI, and metals can be treated at moderate cost by the use of S/S techuologp. 相似文献
646.
Robert G. McLaren Peter A. Forsyth Edward A. Sudicky Joel E. VanderKwaak Franklin W. Schwartz John H. Kessler 《Journal of contaminant hydrology》2000,43(3-4)
Recent discovery of bomb-related 36Cl at depth in fractured tuff in the unsaturated zone at the Yucca Mountain candidate high-level waste (HLW) repository site has called into question the usual modeling assumptions based on the equivalent continuum model (ECM). A dual continuum model (DCM) for simulating transient flow and transport at Yucca Mountain is developed. In order to ensure properly converged flow solutions, which are used in the transport simulation, a new flow solution convergence criteria is derived. An extensive series of simulation studies is presented which indicates that rapid movement of solute through the fractures will not occur unless there are intense episodic infiltration events. Movement of solute in the environs of the repository is enhanced if the properties of the tuff layer at the repository horizon are modified from current best-estimate values. Due to a large advective–dispersive coupling between the matrix and fractures, the matrix acts as a major buffer which inhibits rapid transport along the fractures. Consequently, fast movement of solutes through the fractures to the repository depth can only be explained if the matrix–fracture coupling term is significantly reduced from a value that would be calculated on the basis of data currently available. 相似文献
647.
Numerical simulation of a fine-grained denitrification layer for removing septic system nitrate from shallow groundwater 总被引:1,自引:0,他引:1
Kerry T. B. MacQuarrie Edward A. Sudicky William D. Robertson 《Journal of contaminant hydrology》2001,52(1-4):29-55
One of the most common methods to dispose of domestic wastewater involves the release of septic effluent from drains located in the unsaturated zone. Nitrogen from such systems is currently of concern because of nitrate contamination of drinking water supplies and eutrophication of coastal waters. It has been proposed that adding labile carbon sources to septic distribution fields could enhance heterotrophic denitrification and thus reduce nitrate concentrations in shallow groundwater. In this study, a numerical model which solves for variably saturated flow and reactive transport of multiple species is employed to investigate the performance of a drain field design that incorporates a fine-grained denitrification layer. The hydrogeological scenario simulated is an unconfined sand aquifer. The model results suggest that the denitrification layer, supplemented with labile organic carbon, may be an effective means to eliminate nitrogen loading to shallow groundwater. It is also shown that in noncalcareous aquifers, the denitrification reaction may provide sufficient buffering capacity to maintain near neutral pH conditions beneath and down gradient of the drain field. Leaching of excess dissolved organic carbon (DOC) from the denitrification layer is problematic, and causes an anaerobic plume to develop in simulations where the water table is less than 5-6 m below ground surface; this anaerobic plume may lead to other down gradient changes in groundwater quality. A drain field and denitrification layer of smaller dimensions is shown to be just as effective for reducing nitrate, but has the benefit of reducing the excess DOC leached from the layer. This configuration will minimize the impact of wastewater disposal in areas where the water table is as shallow as 3.5 m. 相似文献
648.
649.
A successful air-based remediation system, now frequently chosen for sites contaminated with VOCs, demands a thorough understanding of the nature and distribution of the VOCs and the soil air permeabilities. Considering likely remediation methods during the site investigation allows collection of all data needed for method selection and design within a single, highly efficient site visit. A case history illustrates how to integrate several data collection and testing activities into a single site visit. 相似文献
650.
Hugh A. Robertson J. Rod Hay Edward K. Saul Gerald V. Mccormack 《Conservation biology》1994,8(4):1078-1086
The Kakerori, or Rarotonga Flycatcher (Pomarea dimidiata) , is an endangered monarch flycatcher endemic to the island of Rarotonga, Cook Islands. This bird was reported to be common until the middle of the nineteenth century, but it declined before 1885 and was thought to be extinct early this century. A small population persisted in the rugged interior of Rarotonga; in 1987 the population stood at 38 birds but was in decline. We determined that introduced predators, especially ship rats (Rattus rattus) , were affecting breeding success. Through a program of experimental management, aimed mainly at rodent control, the population increased from a low of 29 birds in Spring 1989 to 60 birds in Spring 1993. The recovery can be attributed to both improved breeding success and increased adult survivorship. 相似文献