Economics of an integrated approach to control SO2, NOX,HCl, and particulate emissions from power plants

An integrated approach for the simultaneous reduction of major combustion-generated pollutants from power plants is presented along with a simplified economic analysis. With this technology, the synergistic effects of high-temperature sorbent/coal or sorbent/natural gas injection and high-temperature flue gas filtration are exploited. Calcium-based (or Na-based, etc.) sorbents are sprayed in the post-flame zone of a furnace, where they react with S- and Cl-containing gases to form stable salts of Ca (or Na, etc.). The partially reacted sorbent is then collected in a high-temperature ceramic filter, which is placed downstream of the sorbent injection point, where it further reacts for a prolonged period of time. With this technique, both the likelihood of contact and the length of time of contact between the solid sorbent particles and the gaseous pollutants increase, because reaction takes place both in the furnace upstream of the filter and inside the filter itself. Hence, the sorbent utilization increases significantly. Several pollutants, such as SO2, H2S, HCl, and particulate (soot, ash, and tar), may be partially removed from the effluent. The organic content of the sorbents (or blends) also pyrolyzes and reduces NOx. Unburned carbon in the ash may be completely oxidized in the filter. The filter is cleaned periodically with aerodynamic regeneration (back pulsing) without interrupting furnace operation. The effectiveness of this technique has been shown in laboratory-scale experiments using either rather costly carboxylic salts of Ca or low- to moderate-cost blends of limestone, lime, or sodium bicarbonate with coal fines. Injection occurred in the furnace at 1150 degrees C, while the filter was maintained at 600 degrees C. Results showed that 65 or 40% SO2 removal was obtained with calcium formate or a limestone/coal blend, respectively, at an entering calcium-to-sulfur molar ratio of 2. A sodium bicarbonate/coal blend resulted in 78% SO2 removal at a sodium-to-sulfur molar ratio of 2. HCl removal efficiencies have been shown to be higher than those for SO2. NOx reductions of 40% have been observed with a fuel (coal)-to-air equivalence ratio, phi, around 2. The filter has been shown to be 97-99% efficient in removing PM2.5 particulates. Calculations herein show that this integrated sorbent/filter method is cost-effective, in comparison with current technologies, on both capital cost ($/kW) and levelized cost ($/ton pollutant removed) bases, if a limestone/coal mixture is used as the sorbent for fossil fuel plants. Capital costs for the filter/sorbent combination are estimated to be in the range of $61-$105/kW for a new plant. Because current technologies are designed for removing one pollutant at a time, both their cost and space requirements are higher than those of this integrated technique. At the minimum projected removal efficiencies for HCl/SO2/NOx of about 40%, the levelized costs are projected to be $203-$261/ton of combined pollutant SO2/HCl/NOx and particulates removed from coal-fired power plants.     

Assessment of Bioenergy Cropping Scenarios for the Boone River Watershed in North Central Iowa,United States

Several biofuel cropping scenarios were evaluated with an improved version of Soil and Water Assessment Tool (SWAT) as part of the CenUSA Bioenergy consortium for the Boone River Watershed (BRW), which drains about 2,370 km² in north central Iowa. The adoption of corn stover removal, switchgrass, and/or Miscanthus biofuel cropping systems was simulated to assess the impact of cellulosic biofuel production on pollutant losses. The stover removal results indicate removal of 20 or 50% of corn stover in the BRW would have negligible effects on streamflow and relatively minor or negligible effects on sediment and nutrient losses, even on higher sloped cropland. Complete cropland conversion into switchgrass or Miscanthus, resulted in reductions of streamflow, sediment, nitrate, and other pollutants ranging between 23‐99%. The predicted nitrate reductions due to Miscanthus adoption were over two times greater compared to switchgrass, with the largest impacts occurring for tile‐drained cropland. Targeting of switchgrass or Miscanthus on cropland ≥2% slope or ≥7% slope revealed a disproportionate amount of sediment and sediment‐bound nutrient reductions could be obtained by protecting these relatively small areas of higher sloped cropland. Overall, the results indicate that all biofuel cropping systems could be effectively implemented in the BRW, with the most robust approach being corn stover removal adopted on tile‐drained cropland in combination with a perennial biofuel crop on higher sloped landscapes. Editor's note : This paper is part of the featured series on SWAT Applications for Emerging Hydrologic and Water Quality Challenges. See the February 2017 issue for the introduction and background to the series.     

SWAT parameterization for the identification of critical diffuse pollution source areas under data limitations

For lowering sediment, nitrogen (N) and phosphorus (P) pollution of surface water bodies at the catchment scale, environmental legislation require programs of pollution abatement measures. To be able to ensure the cost-effectiveness of such programs we first need to identify high risk areas, which give rise to increased pollutant runoff. Process-based GIS models provide the opportunity to identify such critical areas and hence better target diffuse pollution abatement actions. However, these models are data intensive and their spatially-distributed parameterization in poorly monitored catchments is not feasible without extensive input data pre-processing and significant simplifying assumptions. This study implements the widely-used SWAT river basin model (Soil Water Assessment Tool) to study a medium-sized Greek catchment with the typical data limitations met at the national level, in order to identify critical diffuse pollution source areas that may serve as the key areas for meeting the objective of ‘good ecological status’ of water bodies set by the European Water Framework Directive (WFD). Model parameterization and evaluation are presented along with the decisions made to overcome problems related to data representation in the catchment, in an effort to provide guidance on SWAT modeling in areas with similar characteristics. The results show that sediments and nutrients could be adequately reproduced in large time steps (monthly or seasonal) and that even with the current data limitations, the seasonal variation and the most critical areas of pollutant losses to waters could be adequately identified. The study proposes a transparent modeling approach under data limitations without neglecting possible deficiencies; however, it maintains that the SWAT model, if appropriately parameterized with respect to the land-use and soil differentiation within a limited-gauged catchment, can still facilitate the selection and placement of suitable practices across the landscape for a cost-effective diffused pollution management.     

Application of risk management techniques for the remediation of an old mining site in Greece

This article summarizes the project and risk management of a remediation/reclamation project in Lavrion, Greece. In Thoricos the disposal of mining and metallurgical wastes in the past resulted in the contamination with heavy metals and acid mine drainage. The objective of this reclamation project was to transform this coastal zone from a contaminated site to an area suitable for recreation purposes. A separate risk assessment study was performed to provide the basis of determining the relevant environmental contamination and to rate the alternative remedial schemes involved. The study used both existing data available from comprehensive studies, as well as newly collected field data. For considering environmental risk, the isolation and minimization of risk option was selected, and a reclamation scheme, based on environmental criteria, was applied which was comprised of in situ neutralization, stabilization and cover of the potentially acid generating wastes and contaminated soils with a low permeability geochemical barrier. Additional measures were specifically applied in the areas where highly sulphidic wastes existed constituting active acid generation sources, which included the encapsulation of wastes in HDPE liners installed on clay layers.     

Influence of Bioenergy Crop Production and Climate Change on Ecosystem Services

Land use change can significantly affect the provision of ecosystem services and the effects could be exacerbated by projected climate change. We quantify ecosystem services of bioenergy‐based land use change and estimate the potential changes of ecosystem services due to climate change projections. We considered 17 bioenergy‐based scenarios with Miscanthus, switchgrass, and corn stover as candidate bioenergy feedstock. Soil and Water Assessment Tool simulations of biomass/grain yield, hydrology, and water quality were used to quantify ecosystem services freshwater provision (FWPI), food (FPI) and fuel provision, erosion regulation (ERI), and flood regulation (FRI). Nine climate projections from Coupled Model Intercomparison Project phase‐3 were used to quantify the potential climate change variability. Overall, ecosystem services of heavily row cropped Wildcat Creek watershed were lower than St. Joseph River watershed which had more forested and perennial pasture lands. The provision of ecosystem services for both study watersheds were improved with bioenergy production scenarios. Miscanthus in marginal lands of Wildcat Creek (9% of total area) increased FWPI by 27% and ERI by 14% and decreased FPI by 12% from the baseline. For St. Joseph watershed, Miscanthus in marginal lands (18% of total area) improved FWPI by 87% and ERI by 23% while decreasing FPI by 46%. The relative impacts of land use change were considerably larger than climate change impacts in this paper. Editor's note : This paper is part of the featured series on SWAT Applications for Emerging Hydrologic and Water Quality Challenges. See the February 2017 issue for the introduction and background to the series.     

Employee judgments of and behaviors toward corporate social responsibility: A multi‐study investigation of direct,cascading, and moderating effects

Do employee judgments of their organization's corporate social responsibility (CSR) programs relate to CSR‐specific performance and in‐role job performance? Can middle managers influence the formation of such judgments and what factors might moderate such cascading influences? To answer these yet unaddressed questions, we conduct three studies. Study 1 takes an organizational justice perspective and tests our baseline model. Results show that employees' CSR judgments trigger their affective commitment and performance on extra‐role CSR‐specific behaviors; however, extra‐role CSR‐specific performance is unrelated to in‐role job performance. Study 2 replicates Study 1's findings while, in addition, applies a social information processing approach and offers novel insights by demonstrating the cascading effects of managers' CSR judgments on employee CSR judgments. Investments made in CSR programs in order to improve employee judgments and behaviors may be unsuccessful if employees' CSR judgments are based on social information that remains unchanged. In addition to replicating the findings from studies 1 and 2, study 3 draws from middle management involvement and leadership theories to show that leadership styles and managers' involvement in implementing deliberate strategy can strengthen or weaken these cascading effects. This highlights the important role of middle managers as “linking pins” in the CSR strategy implementation process. Copyright © 2014 John Wiley & Sons, Ltd.     

Integrating Wetland Management into Sustainable Water Resources Allocation: The Case of Akrotiri Wetland in Cyprus

This paper employs a contingent valuation (CV) study to estimate the value of the economic benefits generated by the Akrotiri wetland in Cyprus. It aims to show how CV estimation results can inform efficient, effective and sustainable wetland conservation policies, as required by the European Union's Water Framework Directive, and to suggest economic instruments that can facilitate the implementation of such policies. The results indicate that the design of these instruments require the capturing of both the use and non-use values generated by wetland services and functions.