Modelling atmospheric oxidation of 2-aminoethanol (MEA) emitted from post-combustion capture using WRF–Chem

Abstract

Limiting global warming to less than 2 °C relative to pre-industrial levels would require substantial cuts in anthropogenic emissions of greenhouse gases (IPCC, 2014). Carbon capture and storage (CCS) is an important mitigation technology for reducing anthropogenic carbon dioxide (CO 2 ) emissions from industrial and energy-related point sources. In this process, CO 2 is captured, conditioned, compressed and transported to a storage location for long-term isolation from the atmosphere. Several problems can occur during CCS with impacts on the environment. Post-combustion capture from power plants entails emissions of pollutants, solvents and its degradation by-products to the atmosphere, emissions to water and generation of solid waste (e.g. Reynolds et al., 2012). During the further steps of the CCS chain, CO 2 release during transport in pipelines as well as the escape of injected CO 2 from the storage location to the atmosphere or groundwater pose risks to the environment (Koorneef et al., 2012).Modelling atmospheric oxidation of 2-aminoethanol (MEA) emitted from post-combustion capture using WRF--Chem AbstractCarbon capture and storage (CCS) is a technological solution that can reduce the amount of carbon dioxide (CO 2 ) emissions from the use of fossil fuel in power plants and other industries. A leading method today is amine based post-combustion capture, in which 2-aminoethanol (MEA) is one of the most studied absorption solvents. In this process, amines are released to the atmosphere through evaporation and entrainment from the CO 2 absorber column. Modelling is a key instrument for simulating the atmospheric dispersion and chemical transformation of MEA, and for projections of ground-level air concentrations and deposition rates. In this study, the Weather Research and Forecasting model inline coupled with chemistry, WRF--Chem, was applied to quantify the impact of using a comprehensive MEA photo-oxidation sequence compared to using a simplified MEA scheme. Main discrepancies were found for iminoethanol (roughly doubled in the detailed scheme) and 2-nitro aminoethanol, short MEA-nitramine (reduced by factor of two in the detailed scheme). The study indicates that MEA emissions from a full-scale capture plant can modify regional background levels of isocyanic acid. Predicted atmospheric concentrations of isocyanic acid were however below the limit value of 1 ppbv for ambient exposure. The dependence of the formation of hazardous compounds in the OH-initiated oxidation of MEA on ambient levels level of nitrogen oxides (NO x ) was studied in a scenario without NO x emissions from a refinery area in the vicinity of the capture plant. Hourly MEAnitramine peak concentrations higher than 40 pg m − 3 did only occur when NO x mixing ratios were above 2 ppbv. Therefore, the spatial variability and temporal variability of levels of OH and NO x need to be taken into account in the health risk assessment. The health risk due to direct emissions of nitrosamines and nitramines from full-scale CO 2 capture should be i...

The Eulerian urban dispersion model EPISODE – Part 2: Extensions to the source dispersion and photochemistry for EPISODE–CityChem v1.2 and its application to the city of Hamburg

“…In urban environments, UFPs dominate the total PN concentrations, but only make a small contribution to particulate matter. A simplified parameterization for the treatment of the dry deposition and coagulation of particles (Karl et al, 2016) has already been implemented in EPISODE for modelling PN concentrations in Oslo (Kukkonen et al, 2016). The MAFOR aerosol dynamics solver (Karl et al, 2011(Karl et al, , 2016 will be implemented in EPISODE-CityChem to compute information on the size distribution of UFPs and the total PN.…”

“…A simplified parameterization for the treatment of the dry deposition and coagulation of particles (Karl et al, 2016) has already been implemented in EPISODE for modelling PN concentrations in Oslo (Kukkonen et al, 2016). The MAFOR aerosol dynamics solver (Karl et al, 2011(Karl et al, , 2016 will be implemented in EPISODE-CityChem to compute information on the size distribution of UFPs and the total PN. The solver includes nucleation, coagulation, growth due to the condensation of sulfuric acid, and low volatile and/or semi-volatile organic vapours from biogenic and anthropogenic sources.…”

Photochemical processing of diesel fuel emissions as a large secondary source of isocyanic acid (HNCO)

“…However, direct measurements of the photochemical production of HNCO have only been made in laboratory studies from isolated precursors such as 2-aminoethanol [Borduas et al, 2013]. While modeled HNCO production from 2-aminoethanol oxidation only accounted for 14% of ambient measured HNCO in one study [Karl et al, 2015], ambient mixing ratios of formamide, can account for almost all observed HNCO in some rural environments [Roberts et al, 2014;Sarkar et al, 2015].…”

Re‐carbonation by recycling NaOH‐dissolved ethanol solution for carbon dioxide fixation

“…In the 0th carbonation, the generated precipitates were almost SEC, which indicates that Reaction (4) was dominantly carried out, and the chemical reaction time was 4.8 min. However, the reaction time for Equation (8) obtained from the carbonation under the same condition with the pure water could be estimated to be about 12 min. 27 Therefore, the reaction rate of Equation 8 In addition, ethanol and water are not consumed and generated by the reaction in Equation (8).…”

“…However, the reaction time for Equation (8) obtained from the carbonation under the same condition with the pure water could be estimated to be about 12 min. 27 Therefore, the reaction rate of Equation 8 In addition, ethanol and water are not consumed and generated by the reaction in Equation (8). Therefore, if there is a certain point at which Equation (8) solely occurs during re-carbonation, ECF will remain constant from that point on.…”