David Raper

Environmental capacity and airport operations: current issues and future prospects

Environmental factors and public perceptions already constrain growth at many airports—especially in Europe—and are likely to further constrain aviation in future. In this paper, the way in which these factors influence airport development is considered, together with methods of managing environmental capacity. Environmental limits are inherent to concepts of environmental capacity and sustainability. Although environmental efficiencies in aviation are the subject of considerable research effort, more attention needs to be given to defining and finding commercially viable ways of working within environmental limits.

Commuter exposure to respirable particles inside buses and by bicycle.

The exposure of bus commuters and a cyclist to respirable particles in the city of Manchester has been evaluated, using personal sampling pumps installed in the cabs of the vehicles and carried by the cyclist. These have provided an estimate of the average exposure of commuters using bus services and cycling in a congested European city.

Identifying the contribution of different airport related sources to local urban air quality

The Air Quality Strategy and part IV of The Environment Act, within the United Kingdom, highlight the need for local authorities to undertake air quality assessments. Many UK local authorities have recently completed a review and assessment of local air quality, which has culminated in the declaration of Air Quality Management Areas (AQMAs) in many urban areas, where air pollution objectives are likely to be exceeded. Those local authorities who declare AQMAs are required to undertake a further stage of assessment, which involves the determination of the contribution of various sources of air pollution, such as airports. Many studies of this nature only consider an airport as one source, however, this study considers the impact of different airport related sources on local air quality from a dispersion modelling study of a large urban area. This paper describes the methodology, results and draws conclusions from a study that assesses the impact of a regional airports sources (such as its contribution from road traffic and aircraft). The paper also considers the effect of modelling the above ground aircraft emissions sources (climbout and approach) to different altitude heights. The papers results highlight the need to investigate the source contributions of an airport, to local air quality, as opposed to considering an airport as just one source.

Impact of Alternative Fuels on Emissions Characteristics of a Gas Turbine Engine ? Part 1: Gaseous and Particulate Matter Emissions

Growing concern over emissions from increased airport operations has resulted in a need to assess the impact of aviation related activities on local air quality in and around airports, and to develop strategies to mitigate these effects. One such strategy being investigated is the use of alternative fuels in aircraft engines and auxiliary power units (APUs) as a means to diversify fuel supplies and reduce emissions. This paper summarizes the results of a study to characterize the emissions of an APU, a small gas turbine engine, burning conventional Jet A-1, a fully synthetic jet fuel, and other alternative fuels with varying compositions. Gas phase emissions were measured at the engine exit plane while PM emissions were recorded at the exit plane as well as 10 m downstream of the engine. Five percent reduction in NO(x) emissions and 5-10% reduction in CO emissions were observed for the alternative fuels. Significant reductions in PM emissions at the engine exit plane were achieved with the alternative fuels. However, as the exhaust plume expanded and cooled, organic species were found to condense on the PM. This increase in organic PM elevated the PM mass but had little impact on PM number.

Use of a new generation urban scale dispersion model to estimate the concentration of oxides of nitrogen and sulphur dioxide in a large urban area

This paper describes the use of urban emission inventory data and an urban scale dispersion model (ADMS-Urban) to calculate concentrations of NOx and SO2, in two areas of London, Central London and East London. Local authorities in the UK are expected to undertake reviews of air quality in their areas to determine whether air quality objectives set by the National Air Quality Strategy will be achieved by 2005. The UK Government proposes that local authorities in urban areas develop spatially disaggregated emission inventories in conjunction with dispersion models to assess compliance with the air quality objectives laid down in the strategy. This paper examines the performance of an urban emission inventory and a dispersion model (ADMS-Urban) to assess air quality from emission sources by comparing model predictions with monitored concentrations at four locations. The model used has a GIS interface and uses a spatially disaggregated urban emissions inventory to provide an integrated emission inventory and dispersion modelling system. The dispersion model used in this study is a second-generation Gaussian dispersion model which is characterised by the use of boundary layer similarity profiles to parameterise the variation of turbulence with height within the boundary layer. In a large urban area such as London there are many different sources contributing to the concentrations in the atmosphere. This modelling study aims to examine and evaluate the consideration of both local effects and emissions from the Greater London region. The emissions inventory data for the study are described by a 1×1 km grid covering the Greater London Area which measures 60 km east to west and 45 km north to south. Predicted concentrations for a summer and winter period have been calculated and modelled and measured times series data have been compared. Statistical analyses have been carried out to assist in the comparison of model predictions with monitored data. Although no absolute significance can be attached to the numerical values of these measures, taken cumulatively, some conclusions regarding the emissions inventory data and the model performance can be made.

Evaluation of Methods for Measuring Particulate Matter Emissions from Gas Turbines

The project SAMPLE evaluated methods for measuring particle properties in the exhaust of aircraft engines with respect to the development of standardized operation procedures for particulate matter measurement in aviation industry. Filter-based off-line mass methods included gravimetry and chemical analysis of carbonaceous species by combustion methods. Online mass methods were based on light absorption measurement or used size distribution measurements obtained from an electrical mobility analyzer approach. Number concentrations were determined using different condensation particle counters (CPC). Total mass from filter-based methods balanced gravimetric mass within 8% error. Carbonaceous matter accounted for 70% of gravimetric mass while the remaining 30% were attributed to hydrated sulfate and noncarbonaceous organic matter fractions. Online methods were closely correlated over the entire range of emission levels studied in the tests. Elemental carbon from combustion methods and black carbon from optical methods deviated by maximum 5% with respect to mass for low to medium emission levels, whereas for high emission levels a systematic deviation between online methods and filter based methods was found which is attributed to sampling effects. CPC based instruments proved highly reproducible for number concentration measurements with a maximum interinstrument standard deviation of 7.5%.

Polycyclic Aromatic Hydrocarbon Emissions from the Combustion of Alternative Fuels in a Gas Turbine Engine

We report on the particulate-bound polycyclic aromatic hydrocarbons (PAH) in the exhaust of a test-bed gas turbine engine when powered by Jet A-1 aviation fuel and a number of alternative fuels: Sasol fully synthetic jet fuel (FSJF), Shell gas-to-liquid (GTL) kerosene, and Jet A-1/GTL 50:50 blended kerosene. The concentration of PAH compounds in the exhaust emissions vary greatly between fuels. Combustion of FSJF produces the greatest total concentration of PAH compounds while combustion of GTL produces the least. However, when PAHs in the exhaust sample are measured in terms of the regulatory marker compound benzo[a]pyrene, then all of the alternative fuels emit a lower concentration of PAH in comparison to Jet A-1. Emissions from the combustion of Jet A-1/GTL blended kerosene were found to have a disproportionately low concentration of PAHs and appear to inherit a greater proportion of the GTL emission characteristics than would be expected from volume fraction alone. The data imply the presence of a nonlinear relation between fuel blend composition and the emission of PAH compounds. For each of the fuels, the speciation of PAH compounds present in the exhaust emissions were found to be remarkably similar (R(2) = 0.94-0.62), and the results do provide evidence to support the premise that PAH speciation is to some extent indicative of the emission source. In contrast, no correlation was found between the PAH species present in the fuel with those subsequently emitted in the exhaust. The results strongly suggests that local air quality measured in terms of the particulate-bound PAH burden could be significantly improved by the use of GTL kerosene either blended with or in place of Jet A-1 kerosene.

Impact of Alternative Fuels on Emissions Characteristics of a Gas Turbine Engine − Part 2: Volatile and Semivolatile Particulate Matter Emissions

The work characterizes the changes in volatile and semivolatile PM emissions from a gas turbine engine resulting from burning alternative fuels, specifically gas-to-liquid (GTL), coal-to-liquid (CTL), a blend of Jet A-1 and GTL, biodiesel, and diesel, to the standard Jet A-1. The data presented here, compares the mass spectral fingerprints of the different fuels as measured by the Aerodyne high resolution time-of-flight aerosol mass spectrometer. There were three sample points, two at the exhaust exit plane with dilution added at different locations and another probe located 10 m downstream. For emissions measured at the downstream probe when the engine was operating at high power, all fuels produced chemically similar organic PM, dominated by C(x)H(y) fragments, suggesting the presence of long chain alkanes. The second largest contribution came from C(x)H(y)O(z) fragments, possibly from carbonyls or alcohols. For the nondiesel fuels, the highest loadings of organic PM were from the downstream probe at high power. Conversely, the diesel based fuels produced more organic material at low power from one of the exit plane probes. Differences in the composition of the PM for certain fuels were observed as the engine power decreased to idle and the measurements were made closer to the exit plane.

Environmental ethics and sustainable development

This paper presents a critical analysis of the anthropocentric - nonanthropocentric ethical debate in the context of sustainable development. Traditionally, anthropocentrics are regarded as those who value the environment instrumentally, for the usefulness which certain features of nature have for humans. By contrast, nonanthropocentrics value nature intrinsically, in its own right. In this paper, such a simple bi-modal representation of ethical value is criticized for being too vague. Instead, by examining five dimensions of ethical value, the object of environmental value, the nature of value, the source of value, the theory of value and the attribution of value, it is possible to construct a logically coherent set of environmental ethics which can fully address the concept and implementation of sustainable development.

Wet deposition at the sub-20 km scale in a rural upland area of England

Abstract A network of 10 bulk precipitation collectors was established in an upland region of northern England to examine the small-scale variability of precipitation composition in a rural area. Significant spatial variability was shown for non sea-salt sulphate, calcium and hydrogen ion concentrations. Although nitrate concentrations did not show significant variability, a coherent gradient across the study area was observed. The large variability of calcium ion concentration across the area was related to limestone quarrying, which is prevalent in the south of the study area. Calcareous wind-blown soil may have also made a minor contribution to the abundance of calcium in the rain-water samples. It is likely, however, that a large fraction of the calcium was dry deposited to the funnels of the collectors in the form of particles. The network was not designed to study orographic enhancement of deposition, but it is suggested that this mechanism, along with wind-drift of scavenged cap-cloud droplets, cannot explain the spatial variation in ion concentrations. It is speculated that the variability in non-sea-salt sulphate concentrations may also be partially explained by reaction of CaCO3 particles deposited to the funnels of the collectors with SO2. Critical load exceedances in terms of deposited acidity from non-sea-salt sulphate were calculated using different spatially resolved deposition data. A better estimate of deposition in the study area was achieved by combining rainfall concentration data from the national network with the 5 km rainfall field, than the current methodology used for mapping of U.K. deposition which utilises a 20 km rainfall field. However, 20 km is considered to be the minimum resolution at which a procedure for parameterising orographic enhancement can be incorporated. Deposition and critical load exceedances in 2005 were calculated using a long-range transport model and significant improvements in the protection of soils were predicted from the projected emissions reductions.