With increasing concern over global climate change, policy makers are promoting renewable energy sources, predominantly wind generation, as a means of meeting emissions reduction targets. Although wind generation does not itself produce any harmful emissions, its effect on power system operation can actually cause an increase in the emissions of conventional plants. A dispatch model was developed that analyzes the impact that wind generation has on the operation of conventional plants and the resulting emissions of carbon dioxide (CO/sub 2/), sulphur dioxide (SO/sub 2/), and oxides of nitrogen (NO/sub X/). The analysis concentrates on a "forecasted" approach that incorporates wind generation forecasts in the dispatch decisions. It was found that wind generation could be used as a tool for reducing CO/sub 2/ emissions but alone, it was not effective in curbing SO/sub 2/ and NO/sub X/ emissions.

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Wind generation, power system operation, and emissions reduction

European scientific assessment of the atmospheric effects of aircraft emissions

[1] The series of SULFUR experiments was performed to determine the aerosol particle and contrail formation properties of aircraft exhaust plumes for different fuel sulfur contents (FSC, from 2 to 5500 mg/g), flight conditions, and aircraft (ATTAS, A310, A340, B707, B747, B737, DC8, DC10) This paper describes the experiments and summarizes the results obtained, including new results from SULFUR 7 The conversion fraction e of fuel sulfur to sulfuric acid is measured in the range 034 to 45% for an older (Mk501) and 33 ± 18% for a modern engine (CFM56-3B1) For low FSC, e is considerably smaller than what is implied by the volume of volatile particles in the exhaust For FSC � 100 mg/g and e as measured, sulfuric acid is the most important precursor of volatile aerosols formed in aircraft exhaust plumes of modern engines The aerosol measured in the plumes of various aircraft and models suggests e to vary between 05 and 10% depending on the engine and its state of operation The number of particles emitted from various subsonic aircraft engines or formed in the exhaust plume per unit mass of burned fuel varies from 2 � 10 14 to 3 � 10 15 kg � 1 for nonvolatile particles (mainly black carbon or soot) and is of order 2 � 10 17 kg � 1 for volatile particles >15 nm at plume ages of a few seconds Chemiions (CIs) formed in kerosene combustion are found to be quite abundant and massive CIs contain sulfur-bearing molecules and organic matter The concentration of CIs at engine exit is nearly 10 9 cm � 3  Positive and negative CIs are found with masses partially exceeding 8500 atomic mass units The measured number of volatile particles cannot be explained with binary homogeneous nucleation theory but is strongly related to the number of CIs The number of ice particles in young contrails is close to the number of soot particles at low FSC and increases with increasing FSC Changes in soot particles and FSC have little impact on the threshold temperature for contrail formation (less than 04 K) INDEX TERMS: 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801); 0320 Atmospheric Composition and Structure: Cloud physics and chemistry; 0345 Atmospheric Composition and Structure: Pollution—urban and regional (0305); KEYWORDS: chemiion, sulfur, soot, contrail, aircraft, emission

Influence of fuel sulfur on the composition of aircraft exhaust plumes: The experiments SULFUR 1–7

Flow reactor experiments were performed to study moist CO oxidation in the presence of trace quantities of NO (0–400 ppm) and SO2 (0–1300 ppm) at pressures and temperatures ranging from 0.5–10.0 atm and 950–1040 K, respectively. Reaction profile measurements of CO, CO2, O2, NO, NO2, SO2, and temperature were used to further develop and validate a detailed chemical kinetic reaction mechanism in a manner consistent with previous studies of the CO/H2/O2/NOX and CO/H2O/N2O systems. In particular, the experimental data indicate that the spin-forbidden dissociation-recombination reaction between SO2 and O-atoms is in the fall-off regime at pressures above 1 atm. The inclusion of a pressure-dependent rate constant for this reaction, using a high-pressure limit determined from modeling the consumption of SO2 in a N2O/SO2/N2 mixture at 10.0 atm and 1000 K, brings model predictions into much better agreement with experimentally measured CO profiles over the entire pressure range. Kinetic coupling of NOX and SOX chemistry via the radical pool significantly reduces the ability of SO2 to inhibit oxidative processes. Measurements of SO2 indicate fractional conversions of SO2 to SO3 on the order of a few percent, in good agreement with previous measurements at atmospheric pressure. Modeling results suggest that, at low pressures, SO3 formation occurs primarily through SO2 + O(+M) = SO3(+M), but at higher pressures where the fractional conversion of NO to NO2 increases, SO3 formation via SO2 + NO2 = SO3 + NO becomes important. For the conditions explored in this study, the primary consumption pathways for SO3 appear to be SO3 + HO2 = HOSO2 + O2 and SO3 + H = SO2 + OH. Further study of these reactions would increase the confidence with which model predictions of SO3 can be viewed. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 317–339, 2000

Kinetic modeling of the CO/H2O/O2/NO/SO2 system: Implications for high-pressure fall-off in the SO2 + O(+M) = SO3(+M) reaction

The conversion of fuel sulfur to S(VI) (SO3 + H2SO4) in supersonic and subsonic aircraft engines is estimated numerically. Model results indicate between 2% and 10% of the fuel sulfur is emitted as S(VI). It is also shown that, for a high sulfur mass loading, conversion in the turbine is kinetically limited by the level of atomic oxygen. This results in a higher oxidation efficiency at lower sulfur loadings. SO3 is the primary S(VI) oxidation product and calculated H2SO4 emission levels were less than 1% of the total fuel sulfur. This source of S(VI) can exceed the S(VI) source due to gas phase oxidation in the exhaust wake.

Aircraft exhaust sulfur emissions

Acid dewpoints were calculated from SO 2 -to-SO 3 conversion in gas turbine exhaust. These data can be used as guidelines in setting feedwater temperatures in combined-cycle systems. Accurate settings can prevent corrosion of heat-exchanger (boiler) tubes, thus extending their life time. This study was done using gas turbine engines and a laboratory generator set. The units burned marine diesel or diesel No. 2 fuel with sulfur contents up to 1.3 percent. The exhaust from these systems contained an excess of 20 percent oxygen, and 3-10 percent water vapor. Exhaust temperatures randes from 728 to 893 K (455 to 620 o C)

B. W. Harris

Papers

Conversion of Sulfur Dioxide to Sulfur Trioxide in Gas Turbine Exhaust