Efficient Emission Fees in the U.S. Electricity Sector

This paper provides new estimates of efficient emission fees for sulfur dioxide (SO2) and nitrogen oxides (NOX) emissions in the U.S. electricity sector. The estimates are obtained by coupling a detailed simulation model of the U.S. electricity markets with an integrated assessment model that links changes in emissions with atmospheric transport, environmental endpoints, and valuation of impacts. Efficient fees are found by comparing incremental benefits with emission levels. National quantity caps that are equivalent to these fees also are computed, and found to approximate caps under consideration in the current multi-pollutant debate in the U.S. Congress and the recent proposals from the Bush administration for the electricity industry. We also explore whether regional differentiation of caps on different pollutants is likely to enhance efficiency.emissions trading, emission fees, air pollution, cost-benefit analysis, electricity, particulates, nitrogen oxides, NOx, sulfur dioxide, SO2, health benefits

Direct diffusion through interpenetrating networks: Oxygen in titanium

How impurity atoms move through a crystal is a fundamental and recurrent question in materials. The previous understanding of oxygen diffusion in titanium relied on interstitial lattice sites that were recently found to be unstable, making the diffusion pathways for oxygen unknown. Using first-principles quantum-mechanical methods, we find three oxygen interstitial sites in titanium, and quantify the multiple interpenetrating networks for oxygen diffusion. Surprisingly, no single transition dominates, but all contribute to diffusion.Comment: 10 pages, 3 figures; additional supporting materia

An Update on the Science of Acidification in the Adirondack Park

This paper provides a review of the science pertaining to all aspects of acidification in the Adirondack Park, updating an earlier review of the science (Cook et al. 2002). The review supports an ongoing social science investigation into the willingness to pay for ecological improvements that would result from reduced acid deposition. This paper builds a bridge between the physical science and social science by providing the background that will allow researchers to accurately summarize the crucial elements of ecological status and improvement in a stated preference survey.acid rain, acidification, stated preference, willingness to pay, benefit estimation

Constraints upon water advection in sediments of the Mariana Trough

Thermal gradient measurements, consolidation tests, and pore water compositions from the Mariana Trough imply that water is moving through the sediments in areas with less than about 100 m of sediment cover. The maximum advection rates implied by the thermal measurements and consolidation tests may be as high as 10−5 cm s−1 but are most commonly in the range of 1 to 5×10−6 cm s−1. Theoretical calculations of the effect of the highest advection rates upon carbonate dissolution indicate that dissolution may be impeded or enhanced (depending upon the direction of flow) by a factor of 2 to 5 times the rate for diffusion alone. The average percentage of carbonate is consistently higher in two cores from the area with no advection or upward advection than the average percentage of carbonate in three cores from the area with downward advection. This increase in average amount of carbonate in cores with upward moving water or no movement cannot be attributed solely to differences in water depth or in amount of terrigenous dilution. If the sediment column acts as a passive boundary layer, then the water velocities necessary to affect chemical gradients of silica are in the range 10−9 to 10−10 cm s−l. However, if dissolution of silica occurs within the sediment column, then the advection velocities needed to affect chemical gradients are at least 3×10−8 cm s−l and may be as high as 3×10−6 cm s−l. This order of magnitude increase in advection velocities when chemical reactions occur within the sediments is probably applicable to other cations in addition to silica. If so, then the advection velocities needed to affect heat flow ( >10−8 cm s−1) and pore water chemical gradients are much nearer in magnitude than previously assumed

Cows in the Corn Grazing Project

Corn is the most productive grass grown in Iowa with dry matter yields often exceeding 6 t/a. Harvesting corn by grazing can provide abundant pasture in mid- to late-summer when pastures in southern Iowa normally make little growth. This approach eliminates harvesting, drying, storage, and transportation costs associated with marketing the grain and leaves almost all of the surplus or waste nutrients in the field. Objectives of this project were to measure animal performance when standing corn crop was the sole feed source for pregnant diary heifers and to increase our understanding of the management practices necessary to optimize the use of this feed source

Prediction of water temperature metrics using spatial modelling in the Eastern and Western Cape, South Africa

Key aspects of a river's temperature regime are described by magnitudes, timing and durations of thermal events, and frequencies of extreme exceedance events. To understand alterations to thermal regimes, it is necessary to describe thermal time series based on these statistics. Classification of sites based on their thermal metrics, and understanding of spatial patterns of these thermal statistics, provides a powerful approach for comparing study sites against reference sites. Water temperature regime dynamics should be viewed regionally, where regional divisions have an inherent underpinning by an understanding of natural thermal variability. The aim of this research was to link key water temperature metrics to readily-mapped environmental surrogates, and to produce spatial images of temperature metrics: 37 temperature metrics were derived for 12 months of sub-daily water temperatures at 90 sites in the Eastern Cape and Western Cape provinces, South Africa. These metrics were correlated with 16 environmental variables. Correlations enabled development of multiple regression models which facilitated mapping of temperature metrics over the study area. This approach has the potential to be applied at a national scale as more thermal time series are collected nationally. It is argued that the appropriateness of management decisions in rivers can be improved by including guidelines for thermal metrics at a regional scale. Such maps could facilitate incorporation of a temperature component into management guidelines for water resources

High Frequency (4th order) Sequence Stratigraphy of Early Miocene Deltaic Shorelines, Offshore Texas and Louisiana

DOE-NETL Award Numbers DE-FE0026083 and DEFE0029487Bureau of Economic Geolog