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- ItemCorrelated electron transport in molecular electronics(American Physical Society, 2004) Delaney, Paul A.; Greer, James C.Theoretical and experimental values to date for the resistances of single molecules commonly disagree by orders of magnitude. By reformulating the transport problem using boundary conditions suitable for correlated many-electron systems, we approach electron transport across molecules from a new standpoint. Application of our correlated formalism to benzene-dithiol gives current-voltage characteristics close to experimental observations. The method can solve the open system quantum many-body problem accurately, treats spin exactly, and is valid beyond the linear response regime.
- ItemGas/particle partitioning of carbonyls in the photooxidation of isoprene and 1,3,5-trimethylbenzene(Copernicus Publications on behalf of the European Geosciences Union (EGU), 2008-06-26) Healy, Robert M.; Wenger, John C.; Metzger, Axel; Duplissy, Jonathan; Kalberer, Markus; Dommen, Josef; European CommissionA new denuder-filter sampling technique has been used to investigate the gas/particle partitioning behaviour of the carbonyl products from the photooxidation of isoprene and 1,3,5-trimethylbenzene. A series of experiments was performed in two atmospheric simulation chambers at atmospheric pressure and ambient temperature in the presence of NOx and at a relative humidity of approximately 50%. The denuder and filter were both coated with the derivatizing agent O-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine (PFBHA) to enable the efficient collection of gas- and particle-phase carbonyls respectively. The tubes and filters were extracted and carbonyls identified as their oxime derivatives by GC-MS. The carbonyl products identified in the experiments accounted for around 5% and 10% of the mass of secondary organic aerosol formed from the photooxidation of isoprene and 1,3,5-trimethylbenzene respectively. Experimental gas/particle partitioning coefficients were determined for a wide range of carbonyl products formed from the photooxidation of isoprene and 1,3,5-trimethylbenzene and compared with the theoretical values based on standard absorptive partitioning theory. Photooxidation products with a single carbonyl moiety were not observed in the particle phase, but dicarbonyls, and in particular, glyoxal and methylglyoxal, exhibited gas/particle partitioning coefficients several orders of magnitude higher than expected theoretically. These findings support the importance of heterogeneous and particle-phase chemical reactions for SOA formation and growth during the atmospheric degradation of anthropogenic and biogenic hydrocarbons.
- ItemLong optical cavities for open-path monitoring of atmospheric trace gases and aerosol extinction(Optical Society of America, 2009-02) Varma, Ravi M.; Venables, Dean S.; Ruth, Albert A.; Heitmann, Uwe M.; Schlosser, E.; Dixneuf, SophieAn incoherent broadband cavity-enhanced absorption spectroscopy setup employing a 20 m long optical cavity is described for sensitive in situ measurements of light extinction between 630 and 690 nm. The setup was installed at the SAPHIR atmospheric simulation chamber during an intercomparison of instruments for nitrate (NO3) radical detection. The long cavity was stable for the entire duration of the two week campaign. A detection limit of similar to 2 pptv for NO3 in an acquisition time of 5 s was established during that time. In addition to monitoring NO3, nitrogen dioxide (NO2) concentrations were simultaneously retrieved and compared against concurrent measurements by a chemiluminescence detector. Some results from the campaign are presented to demonstrate the performance of the instrument in an atmosphere containing water vapor and inorganic aerosol. The spectral analysis of NO3 and NO2, the concentration dependence of the water absorption cross sections, and the retrieval of aerosol extinction are discussed. The first deployment of the setup in the field is also briefly described.
- ItemLow temperature germanium to silicon direct wafer bonding using free radical exposure(AIP Publishing, 2010) Byun, Ki Yeol; Ferain, Isabelle; Fleming, Peter G.; Morris, Michael A.; Goorsky, M. S.; Colinge, Cindy; Science Foundation IrelandA low temperature germanium (Ge) to silicon (Si) wafer bonding method was demonstrated by in situ radical activation bonding in vacuum. In order to gain further insight into the bonding mechanism, the Ge surface chemistry after either oxygen or nitrogen radical activation was analyzed by means of angle-resolved x-ray photoelectron spectroscopy. After low temperature direct bonding of Ge to Si followed by annealing at 200 and 300 degrees C, advanced imaging techniques were used to characterize the bonded interface. (C) 2010 American Institute of Physics. (doi: 10.1063/1.3360201)
- ItemIntercomparison of measurements of NO2 concentrations in the atmosphere simulation chamber SAPHIR during the NO3Comp campaign(Copernicus Publications on behalf of the European Geosciences Union., 2010-01) Fuchs, H.; Ball, Stephen M.; Bohn, B.; Brauers, T.; Cohen, R. C.; Dorn, H. P.; Dubé, W. P.; Fry, J. L.; Häseler, R.; Heitmann, Uwe M.; Jones, R. L.; Kleffmann, J.; Mentel, T. F.; Müsgen, P.; Rohrer, F.; Rollins, A. W.; Ruth, Albert A.; Kiendler-Scharr, Astrid; Schlosser, E.; Shillings, A. J. L.; Tillmann, R.; Varma, Ravi M.; Venables, Dean S.; Villena Tapia, G.; Wahner, A.; Wegener, R.; Wooldridge, P. J.; Brown, Steven S.; European Commission; Environmental Protection Agency; Science Foundation Ireland; Sixth Framework ProgrammeNO2 concentrations were measured by various instruments during the NO3Comp campaign at the atmosphere simulation chamber SAPHIR at Forschungszentrum Julich, Germany, in June 2007. Analytical methods included photolytic conversion with chemiluminescence (PC-CLD), broadband cavity ring-down spectroscopy (BBCRDS), pulsed cavity ring-down spectroscopy (CRDS), incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS), and laser-induced fluorescence (LIF). All broadband absorption spectrometers were optimized for the detection of the main target species of the campaign, NO3, but were also capable of detecting NO2 simultaneously with reduced sensitivity. NO2 mixing ratios in the chamber were within a range characteristic of polluted, urban conditions, with a maximum mixing ratio of approximately 75 ppbv. The overall agreement between measurements of all instruments was excellent. Linear fits of the combined data sets resulted in slopes that differ from unity only within the stated uncertainty of each instrument. Possible interferences from species such as water vapor and ozone were negligible under the experimental conditions.
- ItemAerosol properties associated with air masses arriving into the North East Atlantic during the 2008 Mace Head EUCAARI intensive observing period: an overview(Copernicus Publications on behalf of the European Geosciences Union (EGU), 2010-09-07) Dall'Osto, M.; Ceburnis, D.; Martucci, G.; Bialek, J.; Dupuy, R.; Jennings, S. G.; Berresheim, H.; Wenger, John C.; Healy, Robert M.; Facchini, M. C.; Rinaldi, M.; Giulianelli, L.; Finessi, E.; Worsnop, D.; Ehn, M.; Mikkila, J.; Kulmala, Markku; O'Dowd, Colin D.; Environmental Protection Agency; Higher Education Authority; European CommissionAs part of the EUCAARI Intensive Observing Period, a 4-week campaign to measure aerosol physical, chemical and optical properties, atmospheric structure, and cloud microphysics was conducted from mid-May to mid-June, 2008 at the Mace Head Atmospheric Research Station, located at the interface of Western Europe and the N. E. Atlantic and centered on the west Irish coastline. During the campaign, continental air masses comprising both young and aged continental plumes were encountered, along with polar, Arctic and tropical air masses. Polluted-continental aerosol concentrations were of the order of 3000 cm(-3), while background marine air aerosol concentrations were between 400-600 cm(-3). The highest marine air concentrations occurred in polar air masses in which a 15 nm nucleation mode, with concentration of 1100 cm(-3), was observed and attributed to open ocean particle formation. Continental air submicron chemical composition (excluding refractory sea salt) was dominated by organic matter, closely followed by sulphate mass. Although the concentrations and size distribution spectral shape were almost identical for the young and aged continental cases, hygroscopic growth factors (GF) and cloud condensation nuclei (CCN) to total condensation nuclei (CN) concentration ratios were significantly less in the younger pollution plume, indicating a more oxidized organic component to the aged continental plume. The difference in chemical composition and hygroscopic growth factor appear to result in a 40-50% impact on aerosol scattering coefficients and Aerosol Optical Depth, despite almost identical aerosol microphysical properties in both cases, with the higher values been recorded for the more aged case. For the CCN/CN ratio, the highest ratios were seen in the more age plume. In marine air, sulphate mass dominated the sub-micron component, followed by water soluble organic carbon, which, in turn, was dominated by methanesulphonic acid (MSA). Sulphate concentrations were highest in marine tropical air - even higher than in continental air. MSA was present at twice the concentrations of previously-reported concentrations at the same location and the same season. Both continental and marine air exhibited aerosol GFs significantly less than ammonium sulphate aerosol pointing to a significant organic contribution to all air mass aerosol properties.
- ItemSource apportionment of PM2.5 in Cork Harbour, Ireland using a combination of single particle mass spectrometry and quantitative semi-continuous measurements(Copernicus Publications on behalf of the European Geosciences Union (EGU), 2010-10-11) Healy, Robert M.; Hellebust, Stig; Kourtchev, Ivan; Allanic, Arnaud; O'Connor, Ian P.; Bell, Jenny M.; Healy, David A.; Sodeau, John R.; Wenger, John C.; Environmental Protection Agency; Higher Education Authority; Science Foundation IrelandAn aerosol time-of-flight mass spectrometer (ATOFMS) was deployed for the measurement of the size resolved chemical composition of single particles at a site in Cork Harbour, Ireland for three weeks in August 2008. The ATOFMS was co-located with a suite of semi-continuous instrumentation for the measurement of particle number, elemental carbon (EC), organic carbon (OC), sulfate and particulate matter smaller than 2.5 μm in diameter (PM2.5). The temporality of the ambient ATOFMS particle classes was subsequently used in conjunction with the semi-continuous measurements to apportion PM2.5 mass using positive matrix factorisation. The synergy of the single particle classification procedure and positive matrix factorisation allowed for the identification of six factors, corresponding to vehicular traffic, marine, long-range transport, various combustion, domestic solid fuel combustion and shipping traffic with estimated contributions to the measured PM2.5 mass of 23%, 14%, 13%, 11%, 5% and 1.5% respectively. Shipping traffic was found to contribute 18% of the measured particle number (20–600 nm mobility diameter), and thus may have important implications for human health considering the size and composition of ship exhaust particles. The positive matrix factorisation procedure enabled a more refined interpretation of the single particle results by providing source contributions to PM2.5 mass, while the single particle data enabled the identification of additional factors not possible with typical semi-continuous measurements, including local shipping traffic.
- ItemPorous silica spheres as indoor air pollutant scavengers(Royal Society of Chemistry (RSC), 2010-12) Delaney, Paul W.; Healy, Robert M.; Hanrahan, John P.; Gibson, Lorraine T.; Wenger, John C.; Morris, Michael A.; Holmes, Justin D.; Environmental Protection AgencyPorous silica spheres were investigated for their effectiveness in removing typical indoor air pollutants, such as aromatic and carbonyl-containing volatile organic compounds (VOCs), and compared to the commercially available polymer styrene–divinylbenzene (XAD-4). The silica spheres and the XAD-4 resin were coated on denuder sampling devices and their adsorption efficiencies for VOCs evaluated using an indoor air simulation chamber. Real indoor sampling was also undertaken to evaluate the affinity of the silica adsorbents for a variety of indoor VOCs. The silica sphere adsorbents were found to have a high affinity for polar carbonyls and found to be more efficient than the XAD-4 resin at adsorbing carbonyls in an indoor environment.
- ItemComprehensive investigation of Ge-Si bonded interfaces using oxygen radical activation(AIP Publishing, 2011) Byun, Ki Yeol; Fleming, Peter G.; Bennett, Nick; Gity, Farzan; McNally, Patrick; Morris, Michael A.; Ferain, Isabelle; Colinge, Cindy; Science Foundation IrelandIn this work, we investigate the directly bonded germanium-silicon interfaces to facilitate the development of high quality germanium silicon hetero integration at the wafer scale. X-ray photoelectron spectroscopy data is presented which provides the chemical composition of the germanium surfaces as a function of the hydrophilic bonding reaction at the interface. The bonding process induced long range deformation is detected by synchrotron x-ray topography. The hetero-interface is characterized by measuring forward and reverse current, and by high resolution transmission electron microscopy. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3601355]
- ItemGreen grass: developing grass for sustainable gaseous biofuel(University College Cork, 2011) Nizami, Abdul-Sattar; Murphy, Jeremiah D.G.; Department of Agriculture, Food and the MarineGrass is ubiquitous in Ireland and temperate northern Europe. It is a low input perennial crop; farmers are well versed in its production and storage (ensiling). Anaerobic digestion is a well understood technology. Grass is a lignocellulosic feedstock which is fibrous; it can readily cause difficulties with moving parts (wrapping around mixers); it also has a tendency to float. This thesis has an ambition of establishing the ideal digester configuration for production of biogas from grass. After extensive analysis of the literature, two different digester systems were designed, fabricated, commissioned and operated. The first system was a two stage wet continuous system commonly referred to as a Continuously Stirred Tank Reactor (CSTR). The second was a two stage, two phase system employing Sequentially Fed Leach Beds complete with an Upflow Anaerobic Sludge Blanket (SLBR-UASB). These were operated on the same grass silage cut from the same field at the same time. Small biomethane potential (BMP) assays were also evaluated for the same grass silage. The results indicated that the CSTR system produced 451 L CH4 kg-1 VS added at a retention time of 50 days while effecting a 90% destruction in volatile dry solids. The SLBR-UASB produced 341 L CH4 kg-1 VS added effecting a 75% reduction in volatile solids at a retention time of 30 days. The BMP assays generated results in the range 350 to 493 L CH4 kg-1 VS added. This thesis concludes that a disparity exists in the BMP tests used in the industry. The CSTR when designed specifically for grass silage is shown to be extremely effective in methane production. The SLBR-UASB has significant potential to allow for lower retention times with good levels of methane production. This technology has more potential for research in enzymatic hydrolysis and for use of digestate in added value products.
- ItemA broadband optical cavity spectrometer for measuring weak near-ultraviolet absorption spectra of gases(Copernicus Publications on behalf of the European Geosciences Union., 2011-01) Chen, Jun; Venables, Dean S.; Science Foundation Ireland; European CommissionAccurate absorption spectra of gases in the near-ultraviolet (300 to 400 nm) are essential in atmospheric observations and laboratory studies. This paper describes a novel incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) instrument for measuring very weak absorption spectra from 335 to 375 nm. The instrument performance was validated against the B-3(1)-X(1)A(1) transition of SO2. The measured absorption varied linearly with SO2 column density and the resulting spectrum agrees well with published spectra. Using the instrument, we report new absorption cross-sections of O-3, acetone, 2-butanone, and 2-pentanone in this spectral region, where literature data diverge considerably. In the absorption minimum between the Huggins and Chappuis bands, our absorption spectra fall at the lower range of reported ozone absorption cross-sections. The spectra of the ketones agree with prior spectra at moderate absorptions, but differ significantly at the limits of other instruments' sensitivity. The collision-induced absorption of the O-4 dimer at 360.5 nm was also measured and found to have a maximum cross-section of ca. 4.0 x 10(-46) cm(5) molecule(-2). We demonstrate the application of the instrument to quantifying low concentrations of the short-lived radical, BrO, in the presence of stronger absorptions from Br-2 and O-3.
- ItemShort duration rainfall extremes in Ireland: influence of climatic variability(Springer Netherlands for European Water Resources Association, 2011-02) Leahy, Paul G.; Kiely, Gerard; Science Foundation Ireland; Environmental Protection AgencyA widely-noted change in the North Atlantic circulation in the 1970s affected the spatial distribution and seasonal pattern of rainfall over Ireland. To examine if this was accompanied by a change on short duration precipitation extremes, multi-decadal time series from the second half of the twentieth century of thirteen hourly precipitation stations in Ireland have been analysed for the occurrence of extreme values over several durations of up to 24 h. Strong evidence was found for a change since the late 1970s in short duration rainfall depths, particularly in the west of the country. Precipitation depth-duration-frequency analyses over two sub-periods showed that at several locations, storm event magnitudes which corresponded to a 30 year return period before 1975 had a return period close to 10 years in the post-1975 period. The widespread increase in spring and autumn rainfall and the local increases in the frequencies and magnitudes of severe rainfalls have implications for engineering hydrology, flood risk analysis and water resources management. The necessity of using up-to-date data to derive design storm magnitudes is stressed, due to the possible influence of underlying climatic shifts. Furthermore, as non-stationarity has been demonstrated, the use of long timeseries extending beyond thirty years into the past will result in underestimation of storm intensities in many areas.
- ItemENVIRON 2011: 21st Irish Environmental Researchers Colloquium(University College Cork, Environmental Protection Agency and Environmental Sciences Association of Ireland (ESAI), 2011-04) Bolger, Paul; Environmental Protection AgencyThe theme of this year’s colloquium is “Towards 2020: Environmental challenges and opportunities for the next decade” which reflects the many environmental targets that have been set for the year 2020 in areas of climate change, renewable energy, water protection and biodiversity. In relation to the latter, we are delighted to have Professor Michael Depledge (Former Chairman of UK Science Advisory Committee on the Environment & Climate Change) at ENVIRON 2011 to deliver the colloquium keynote address on “Health and the Value of Nature”. The colloquium plenary session has a number of high profile speakers who will address the colloquium theme of environmental challenges and opportunities for the next decade including Professor John Sweeney (NUI Maynooth), Ms Laura Burke (Director of EPA’s Office of Climate, Licensing Research and Resource Use) and Mr John Mullins (CEO of Bord Gais). The research programme has 95 oral presentations and 60 poster presentations in the themes of water quality, energy and climate change, marine and coastal research, environmental management, environmental technologies, environment and health, and biodiversity and ecosystems. In addition, for the first year, poster presenters have the opportunity to make a 1 minute oral presentation on their poster during the oral sessions in the relevant theme. The 2011 colloquium also sees an increase the number of workshops and seminars accompanying the programme with an emphasis on training and development for postgraduates in the environmental area. We are particularly pleased to have a link with the Environment Graduate Programme in the “Ocean Studies Workshop” which illustrates how the ENVIRON colloquium can support and benefit from the various graduate programmes currently being developed within Universities. Finally ENVIRON 2011 and the UCC 2011 Law and the Environment symposium have been deliberately scheduled together at the same time and location to allow delegates from both conferences to benefit from each other’s programmes.
- ItemNear-ultraviolet absorption cross sections of nitrophenols and their potential influence on tropospheric oxidation capacity(American Chemical Society, 2011-09-29) Chen, Jun; Wenger, John C.; Venables, Dean S.; European Commission; Science Foundation IrelandNitrophenols and methylnitrophenols have been identified as photolytic precursors of nitrous acid, HONO, but their gas-phase absorption has not previously been reported. In this study, the absorption cross sections of 2-nitrophenol, 3-methyl-2-nitrophenol, and 4-methyl-2-nitrophenol were measured from 320 to 450 nm using incoherent broad-band cavity enhanced absorption spectroscopy (IBBCEAS). The benzaldehyde absorption spectrum wasmeasured to validate the approach and was in good agreement with literature spectra. The nitrophenol absorption cross sections are large (ca. 10-17 cm2 molecule-1) and blue-shifted about 20 nm compared to previously measured solution spectra. Besides forming HONO, nitrophenol absorption influences other photochemistry by reducing the available actinic flux. The magnitudes of both effects are evaluated as a function of solar zenith angle, and nitrophenol absorption is shown to lower the photolysis rates of O3 and NO2.
- ItemThe broad-scale distribution and abundance of Scyphomedusae in Irish waters(University College Cork, 2011-11) Bastian, Thomas Jean Daniel; Doyle, Thomas K.; McAllen, Robert; Davenport, John; European Regional Development FundScyphomedusae are receiving increasing recognition as key components of marine ecosystems. However, information on their distribution and abundance beyond coastal waters is generally lacking. Organising access to such data is critical to effectively transpose findings from laboratory, mesocosm and small scale studies to the scale of ecological processes. These data are also required to identify the risks of detrimental impacts of jellyfish blooms on human activities. In Ireland, such risks raise concerns among the public, but foremost amongst the professionals of the aquaculture and fishing sectors. The present work looked at the opportunity to get access to new information on the distribution of jellyfish around Ireland mostly by using existing infrastructures and programmes. The analysis of bycatch data collected during the Irish groundfish surveys provided new insights into the distribution of Pelagia noctiluca over an area >160 000 km2, a scale never reached before in a region of the Northeast Atlantic (140 sampling stations). Similarly, 4 years of data collected during the Irish Sea juvenile gadoid fish survey provided the first spatially, explicit, information on the abundance of Aurelia aurita and Cyanea spp. (Cyanea capillata and Cyanea lamarckii) throughout the Irish Sea (> 200 sampling events). In addition, the use of ships of opportunity allowed repeated samplings (N = 37) of an >100 km long transect between Dublin (Ireland) and Holyhead (Wales, UK), therefore providing two years of seasonal monitoring of the occurrence of scyphomedusae in that region. Finally, in order to inform the movements of C. capillata in an area where many negative interactions with bathers occur, the horizontal and vertical movements of 5 individual C. capillata were investigated through acoustic tracking.
- ItemWhat will fuel transport systems of the future?(Elsevier, 2011-11-17) Murphy, Jerry D.; Thamsiriroj, Thanasit; Science Foundation Ireland; Higher Education Authority; Environmental Protection Agency; Department of Agriculture, Food and Fisheries, Ireland; Bord Gáis EireannThis paper seeks to decry the notion of a single solution or “silver bullet” to replace petroleum products with renewable transport fuel. At different times, different technological developments have been in vogue as the panacea for future transport needs: for quite some time hydrogen has been perceived as a transport fuel that would be all encompassing when the technology was mature. Liquid biofuels have gone from exalted to unsustainable in the last ten years. The present flavor of the month is the electric vehicle. This paper examines renewable transport fuels through a review of the literature and attempts to place an analytical perspective on a number of technologies.
- ItemCoastal iodine emissions: part 2. Chamber experiments of particle formation from Laminaria digitata-derived and laboratory-generated I2(American Chemical Society, 2012) Monahan, Ciaran; Ashu-Ayem, Enowmbi R.; Nitschke, Udo; Darby, Steven B.; Smith, Paul D.; Stengel, Dagmar B.; Venables, Dean S.; O'Dowd, Colin D.; Science Foundation Ireland; Irish Research Council for Science Engineering and Technology; European CommissionLaboratory studies into particle formation from Laminaria digitata macroalgae were undertaken to elucidate aerosol formation for a range of I2 (0.3−76 ppbv) and O3(<3−96 ppbv) mixing ratios and light levels (EPAR = 15, 100,and 235 μmol photons m−2 s−1). No clear pattern was observed for I2 or aerosol parameters as a function of light levels. Aerosol mass fluxes and particle number concentrations,were, however, correlated with I2 mixing ratios for low O3mixing ratios of <3 ppbv (R2 = 0.7 and 0.83, respectively for low light levels, and R2 = 0.95 and 0.98, respectively for medium lightlevels). Additional experiments into particle production as a function of laboratory-generated I2, over a mixing ratio range of 1−8ppbv, were conducted under moderate O3 mixing ratios (∼24 ppbv) where a clear, 100-fold or greater, increase in the aeroso lnumber concentrations and mass fluxes was observed compared to the low O3 experiments. A linear relationship between particle concentration and I2 was found, in reasonable agreement with previous studies. Scaling the laboratory relationship to aerosol concentrations typical of the coastal boundary layer suggests a I2 mixing ratio range of 6−93 pptv can account for the observed particle production events. Aerosol number concentration produced from I2 is more than a factor of 10 higher than thatproduced from CH2I2 for the same mixing ratios.
- ItemCoastal iodine emissions. 1. Release of I2 by Laminaria digitata in chamber experiments(American Chemical Society, 2012) Ashu-Ayem, Enowmbi R.; Nitschke, Udo; Monahan, Ciaran; Chen, Jun; Darby, Steven B.; Smith, Paul D.; O'Dowd, Colin D.; Stengel, Dagmar B.; Venables, Dean S.; Science Foundation Ireland; Irish Research Council for Science Engineering and TechnologyTidally exposed macroalgae emit large amounts of I2 and iodocarbons that produce hotspots of iodine chemistry and intense particle nucleation events in the coastal marine boundary layer. Current emission rates are poorly characterized, however,with reported emission rates varying by 3 orders of magnitude. In this study, I2 emissions from 25 Laminaria digitata samples were investigated in a simulation chamber using incoherent broadbandcavity-enhanced absorption spectroscopy (IBBCEAS). The chamber design allowed gradual extraction of seawater to simulate tidal emersion of algae. Samples were exposed to air with or without O3 and to varying irradiances. Emission of I2 occurred in four distinct stages: (1) moderate emissions from partially submerged samples;(2) a strong release by fully emerged samples; (3) slowing or stopping of I2 release; and (4) later pulses of I2 evident in some samples. Emission rates were highly variable and ranged from 7to 616 pmol min−1 gFW−1 in ozone-free air, with a median value of 55 pmol min−1 gFW−1 for 20 samples.
- ItemPersistence of low wind speed conditions and implications for wind power variability(John Wiley & Sons, Ltd., 2012) Leahy, Paul G.; McKeogh, Eamon J.; Science Foundation Ireland; Enerco Energy IrelandAs the penetration of wind generation increases on power systems throughout the world, the effects of wind variability on power systems are of increasing concern. This study focuses on sustained occurrences of low wind speeds over durations ranging from 1 h to 20 days. Such events have major implications for the variability of energy yields from wind farms. This, in turn, influences the accuracy of wind resource assessment. The frequency analysis techniques commonly used to study wind variability cannot represent the autocorrelation properties of wind speeds and thus provide no information on the probabilities of occurrence of such sustained, low wind events. We present two complementary methods for assessing wind variability, runs analysis and intensity–duration–frequency analysis, both with emphasis on characterising the occurrence of continuous, extended periods (up to several days) of low wind speeds. Multi-annual time series of hourly wind speeds from meteorological stations in Ireland are analysed with both techniques. Sustained 20-day periods corresponding to extremely low levels of wind generation are found to have return periods of around 10 years in coastal areas. Persistent, widespread low wind speed conditions across the entire country are found to occur only rarely.
- ItemIrish TIMES Energy Systems Model(Environmental Protection Agency, 2012) Ó Gallachóir, Brian P.; Chiodi, Alessandro; Gargiulo, Maurizio; Deane, Paul; Lavigne, Denis; Rout, Ullash Kumar; Department of Jobs, Enterprise and InnovationIreland faces very challenging short-term targets in the period to 2020 arising from EU obligations that are specified in EU Directives and Decisions. In addition to these short-term targets, the EU has committed to a long-term greenhouse gas (GHG) emissions reduction of 80–95% below 1990 levels by 2050, and will require Member States to participate in effort-sharing to deliver deep emissions cuts. Policy-makers require comprehensive, robust, knowledge-based information to inform their decisions on how to meet these targets in a manner that will most benefit the Irish economy. This project draws on and contributes to the wealth of international energy-systems modelling research activity. It involved building, developing, calibrating, testing and running a (partial equilibrium) energysystems optimisation model for Ireland – the Irish TIMES model. The model was developed by University College Cork in collaboration with the Economic and Social Research Institute, E4SMA and KanORS over the period March 2009–November 2011. The real value of the Irish TIMES model is in the new insights it gives into some of the key challenges and decisions facing Ireland in energy and climate policy. The Irish TIMES model provides a means of assessing the implications of alternative future energy system pathways for: (i) the Irish economy (technology choices, prices, output, etc.), (ii) Ireland’s energy mix and energy dependence, and (iii) the environment. It is used in this project to assess the implications of emerging technologies and of mobilising alternative policy choices, such as meeting renewable energy targets and carbonmitigation strategies. The two key new perspectives this research project gives are: (i) a full energy-systems modelling approach and (ii) a focus on the medium term (to 2050) as well as the short term (to 2020). The scenario results respond directly to a number of key policy questions that could not be readily addressed before this model was developed. These relate to Ireland’s targets for: (i) renewable energy to 2020, (ii) GHG reduction to 2020 and (iii) long-term GHG emissions reduction to 2050. The results point to: 1 Alternative pathways for renewable energy to that currently being followed under Ireland’s National Renewable Energy Action Plan (NREAP); 2 The need to urgently reassess Ireland’s renewable energy policies in light of the non-ETS emissions reduction target; 3 A particular focus on renewable heat, renewable transport and electrification of heat, in contrast to the current dominant focus on wind-generated electricity; 4 The impacts of imposing a higher emissions reduction target on Ireland’s energy system to compensate for limited mitigation options in agriculture; 5 The significant challenges in moving to a lowcarbon economy in 2050 with renewable energy accounting for 65–85% of energy supply (compared with 6.5% in 2011); 6 Electrification of heat in particular but also of transport, resulting in the share of energy use delivered by electricity increasing from 18% currently to 31–47% of energy use in 2050.