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This paper investigates the relationships among the important process parameters that impact Post-combustion Carbon Capture (PCC) carbon dioxide (C O 2) separation. A better understanding of the complex relationships among those parameters can support optimization and performance enhancement of the separation process. Being able to precisely predict the process parameters will enable the operator to determine the current state of the process, forecast any potential changes or events, and adjust process parameters to enhance the plant's performance. With the objective of studying the process parameters' correlations in the amine-based PCC process, we modeled the multi-year historical production data of the Clean Energy Technologies Research Institute (CETRi) (formerly known as the International Test Center for PCC or ITC) in Regina, Saskatchewan, Canada, using a Decision Forest approach. The model validation process revealed that the Decision Forest model produced higher predictive accuracy than previous efforts. The Decision Forest models we developed also represent knowledge about the importance of parameters involved in the capture process, and such knowledge is useful for further optimization of the capture process in the future. • Modeling the parameters of the Carbon Capture process with machine learning (ML). • The ML models used Decision Forest with Gradient Boosting and Oblique Split. • The ML models achieved superior predictive accuracy compared to past efforts. • The ML models support interpretability by visualizing weights and prediction paths. [ABSTRACT FROM AUTHOR]

• New carbon-sequestration geosystem paradigm proposed for screening CO 2 repositories. • Deposition, burial history 1st-order controls on repository attributes, traps, etc. • Genetic understanding of geology enables property prediction away from data control. • Case-study application to heavily industrialized region of onshore Canada. In this paper, I propose a new geoscience paradigm for evaluating potential carbon-sequestration targets. I introduce the term carbon-sequestration geosystem to study and describe portions of sedimentary basins where all the geologic components necessary for the safe and long-term storage of CO 2 are present. The purpose of this type of analysis, most appropriately applied at a basin-screening stage, is to derive a holistic, genetic, and predictive understanding of the geology – the depositional systems, structural setting and other factors that are direct controls on storage, injectivity, potential for induced seismicity, and other critical factors. To illustrate the concepts, I present a re-evaluation of the geologic carbon-sequestration options in Southern Ontario (Canada) where business and environmental needs, mostly associated with hard-to-abate industries, require urgent action. Legacy wireline-logs, core, and outcrop data are the main data sources available in this onshore setting. The results of this new, independent study are broadly similar to those of previous studies: the Cambrian section, a saline aquifer, is the most likely candidate to be a CO 2 repository. However, the methodology used identified several issues (e.g., stratigraphic heterogeneity, proximity to basement) that will need addressing by targeted data collection and/or analysis before site-selection for a test should be undertaken. [ABSTRACT FROM AUTHOR]

In the pursuit of mitigating the performance gap between model-predicted thermal comfort and measurements of perceived thermal comfort, recent studies have investigated the multi-domain nature of thermal comfort and IEQ. This paper presents an update to a recent work that applied Bayesian logistic regression to examine possible independent correlations between perceived thermal comfort of building occupants and metrics of indoor environmental quality (IEQ) such as CO 2 concentrations. The prior work made use of the COPE dataset, a 20-year-old field database of objective and subjective IEQ measurements collected from approximately 800 occupants of open-plan offices in large Canadian and US cities. This study updates that work with a new IEQ field study of 141 workstations carried out at the University of British Columbia across 2019 and 2020. In addition, a new, hierarchical (multi-level) Bayesian logistic regression model is formulated and applied. The new results not only increase the credibility of observing measurements of CO 2 concentrations to improve predictions of thermal satisfaction in the original COPE dataset, but that the credibility of this evidence is strengthened on the addition of the new data. At indoor temperatures of 23.5 °C, the probability of an occupant feeling thermally satisfied at measured CO 2 levels of 550 ppm was 0.62 [0.54 - 0.69, 95% CrI]. This decreased to 0.28 [0.17-0.42, 95% CrI] at 750 ppm. This study does not suggest these observations are generalizable outside the COPE and UBC datasets, nor does it suggest that CO 2 must be affecting occupants physiologically or psychologically to cause these observations. However, it is suggested that CO 2 levels may remain overlooked as a contextual, or latent variable for the real-time prediction of perceived thermal comfort in buildings. For instance, prior research has observed a relationship between indoor CO 2 levels and perceived air quality as well as a relationship between multiple perceptual factors of IEQ, such as air quality and thermal comfort. If the findings of this paper continue to be found in future studies, measurements of CO 2 concentrations may be used to improve the accuracy of thermal comfort prediction models. The core recommendation for future work is therefore to expand measurements in future thermal comfort field studies to include, at least, measurements of indoor CO 2 levels. A greater dataset is needed to determine whether the findings of this study are possibly universally applicable, and/or whether knowledge of indoor CO 2 concentrations may improve personalized models of thermal comfort that are building- and context-specific. • A new IEQ field study of office workers in Canada adds 141 samples to a prior dataset. • The newly collected IEQ database is publicly accessible as part of this publication. • The data is applied to a new hierarchical Bayesian logistic regression model. • Indoor CO 2 levels are found to credibly improve predictions of thermal satisfaction. • Increases in CO 2 levels correlate to observed decreases in thermal satisfaction. [ABSTRACT FROM AUTHOR]

The Neoproterozoic St Honoré carbonatite complex is one of three currently mined niobium deposits. In these and most other carbonatite-hosted niobium deposits, pyrochlore is the principal ore mineral. Four major pyrochlore-bearing rock types are observed in the St Honoré complex, namely, biotitite, magnetite-biotite rock, apatitite and carbonatite. The textural relationships among the different rock types and within each rock type are extremely complex, as are the textures and crystal chemistry of the pyrochlore. Compositionally, there are two major types of pyrochlore. Type-1 is enriched in Ta, U, Zr, Sr, Th, Fe, REE and Cl and Type-2 is a Ca-Na-F-rich pyrochlore, with proportions of other elements close to or below their detection limits. Type-1 pyrochlore is yellow- to red-brown and, in many cases, displays oscillatory zoning. This variety occurs most commonly in the cores of crystals in apatitite, where it has its highest concentrations of the elements listed above. It also is observed in biotitite, but the proportions of the above elements are much lower. Type-2 pyrochlore is light to dark brown and, generally, does not exhibit oscillatory zoning. It forms overgrowths on Type-1 pyrochlore in apatitite and biotitite, and occurs as large crystals in the magnetite-biotite rock (Type-1 pyrochlore is not present in this rock). We propose that Type-1 pyrochlore crystallised from a highly evolved, fluid-undersaturated carbonatitic magma, whereas Type-2 pyrochlore crystallised from a carbonatitic magma that had undergone fluid exsolution, which depleted the magma in elements that tend to partition preferentially into aqueous fluids, i.e., U, Sr, Fe, REE, Ba and Cl. The processes that governed the evolution of the carbonatitic magma (which was mantle-derived and introduced in numerous small batches) and crystallisation of pyrochlore at St Honoré were biotitisation (by the magma), crystallisation of calcite and aqueous fluid exsolution. Biotitisation of the host syenite consumed MgO, H 2 O and CO 2 from each magma batch (the CO 2 was released as a gas), leading to the crystallisation of Type-1 pyrochlore in biotitite. This process also locally increased the CaO content of the magma to a level sufficient to saturate it with calcite, leaving a residual phoscoritic magma that crystallised the most Ta-U-enriched variety of Type-1 pyrochlore. Exsolution of the aqueous fluid occurred as a result of prolonged crystallisation and/or pressure release and led to the crystallisation of Type-2 pyrochlore. The evolution of each of the magma batches was different and depended on the extent of biotitisation, on whether calcite crystallised, and on the timing of fluid exsolution. As the two types of pyrochlore and their temporal relationship have been described for many carbonatite complexes, the hypotheses presented in this paper are likely also applicable to the genesis of pyrochlore in these other complexes. [ABSTRACT FROM AUTHOR]

Improving the environmental performance of built environments has received wider interest in the recent past. Asset management is an under-utilized strategy to enhance and maintain desired environmental performance of a building at low life cycle costs (LCC). Current asset management decision-making methods are not fully capable of incorporating future technological changes and complex time sensitive environmental demands. There is a knowledge gap in incorporating factors such as environmental performance, risk and time sensitivity to foster dynamic asset management decision making. This paper presents a multi-period asset management method for public buildings to minimize LCC and attain climate action goals. A scenario planning approach is used to incorporate future changes in technologies, costs and organizational policies. Risk based prioritization is used to compare and select maintenance alternatives in a given period. Value at risk is used to identify the lowest risk capital planning strategy for an organization. The proposed approach was demonstrated using an operating aquatic centre building in British Columbia, Canada. Three possible future scenario were considered. Proposed method was used to develop multi-period maintenance plans for future scenarios. Based on the analysis, Great Transitions scenario is expected to achieve the least financial risk. The proposed approach enable capital asset planning by complying with changing climate action targets in a stochastic environment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Post-plasma constriction of a CO 2 microwave plasma enhances conversion and energy efficiency. • Increased performance is the result of enhanced molecular transport from the plasma region. • 3D CFD simulations showed that the constriction encourages product retention, which results in increased performance. Transforming CO 2 into value-added chemicals is crucial to realizing a carbon–neutral economy, and plasma-based conversion, a Power-2-X technology, offers a promising route to realizing an efficient and scalable process. This paper investigates the effects of post-plasma placement of a converging–diverging nozzle in a vortex-stabilized 2.45 GHz CO 2 microwave plasma reactor to increase energy efficiency and conversion. The CDN leads to a 21 % relative increase in energy efficiency (31 %) and CO 2 conversion (13 %) at high flow rates and near-atmospheric conditions. The most significant performance improvement was seen at low flow rates and sub-atmospheric pressure (300 mbar), where energy efficiency was 23 % and conversion was 28 %, a 71 % relative increase over conditions without the CDN. Using CFD simulations, we found that the CDN produces a change in the flow geometry, leading to a confined temperature profile at the height of the plasma, and forced extraction of CO to the post-CDN region. [ABSTRACT FROM AUTHOR]

Empirical studies of the EKC hypothesis may be very sensitive to datasets, specifications, and functional forms. The aim of this paper is to investigate the long-run relationship among CO 2 emissions, real GDP, and energy consumption using a panel of 9 advanced economies from 1870 to 2008 using both parametric and semi-parametric additive models. While at the panel level the results provide support to the Environmental Kuznets Curve (EKC) only in the post-1950s period, at the individual country level the inverted U-shaped relationship between CO 2 and real GDP is validated for a subset of countries only. However, when a semi-parametric regression framework is applied an inverse U-shaped pattern becomes clear for all countries of the sample, except Canada. Empirical findings indicate that relaxing the restrictions associated with parametric regression models may be critical for the question of investigating the existence of the EKC. • Panel data results provide support to the EKC only in the post-1950s period. • Semi-parametric regressions reveal an inverse U-shaped pattern for all countries, except Canada • An effective policy to reduce CO 2 emissions should encourage innovation activities in low-emission technologies. [ABSTRACT FROM AUTHOR]

Abstract: This paper will discuss TRIPLEX-Flux, a process-based model that estimates net ecosystem production (NEP) as well as analyzing the level of sensitivity of the model''s response by simulating CO2 flux in an existing old black spruce BOREAS site in central Canada. The research objectives were: (1) to test the TRIPLEX-Flux model simulations against flux tower measurements; and (2) to examine parameter and input variable effects on model response via sensitivity analysis. Validation of NEP data at 30min intervals derived from tower and chamber measurements showed that the NEP data from the model corresponded well with the measured NEP from the BOREAS site (R 2 >0.65). Sensitivity analysis demonstrated different levels of sensitivity between morning and noon periods and from the current to doubled atmospheric CO2 concentrations. Additionally, the comparison of different algorithms to calculate stomatal conductance showed that the NEP predicted by the model using the iteration algorithm was consistent with the results using a constant C i/C a of 0.74 for current and 0.81 for doubled CO2 concentrations. Varying parameter and input variable values by ±10% resulted in a similar model response between morning and noon periods (less than or equal to 27.6% and 27.4%, respectively). Most parameters were more sensitive at noon than they were in the morning except for those that were correlated with air temperature, suggesting that air temperature has considerable influence over model sensitivity for these parameters/variables. Air temperature effect was greater under doubled than it was under current atmospheric CO2 concentrations. In contrast, model sensitivity to CO2 decreased under doubled CO2 concentrations. [Copyright &y& Elsevier]

Abstract: Local-scale wind regimes over an idealized two-dimensional (2D) mountain having similar horizontal and vertical scales as Vancouver Island were investigated using a high-resolution mesoscale model. The model-generated flow outputs were then used as ersatz data to assess the impact of limiting assumptions in the eddy-covariance (EC) method as well as the effectiveness of tower flux data time-filtering for the main tower site of the Fluxnet-Canada British Columbia flux station. In this paper, we describe the simulated mesoscale and local-scale flow regimes, and in Part II we describe their use in assessing tower-data analyses of CO2 fluxes. The numerical model was enhanced to include parameterizations for: tree drag, radiation effects of forest canopies on the surface energy budget, and soil heat conduction. Simulations were performed both over an idealized bare hill and over a forested hill. The simulated flow involved interactions between the land/sea breeze, convective thermals, and mountain circulations under fair-weather conditions. The resulting simulated winds over the forested slope were much weaker than those over a bare slope. The nocturnal drainage flow over the forested slope was separated into sub-canopy and above-canopy regimes due to the temperature inversion at treetop. The strongest downslope flows occurred above the canopy with a minimum velocity occurring in the upper canopy where canopy drag is the strongest. The overturning of large convective eddies during daytime resulted in intermittent downslope flows under the canopy during the day. Wind regimes had a rapid shift from upslope to downslope flow above the canopy just after sunset. Further testing will be made using 3D simulations with higher resolution. [Copyright &y& Elsevier]

Abstract: A long-term flux measurement station has been established in a 74-year-old mixedwood forest ecosystem, located approximately 80km west of Timmins in northern Ontario, as part of the Fluxnet-Canada Research Network (FCRN). Measurements of energy, water vapour, and carbon dioxide fluxes have been made continuously since August 2003 using the eddy covariance technique, along with ancillary meteorological variables. The spatial structure of the site was evaluated using a variety of sources and techniques, including remote sensing, showing that this forest is mixed but relatively homogeneous. The canopy top height is remarkably constant at between 30 and 32m. The basal area varies from 18 to 27m2 ha−1, and the aboveground biomass ranges from 82 to 122Mgha−1. In this paper, we summarize the diurnal and seasonal patters of carbon dioxide exchange and water loss from September 1, 2003 to August 31, 2004. Net ecosystem productivity (NEP) is strongly related to temperature. Atmospheric vapour pressure deficit (VPD) in this ecosystem exerted strong biophysical control on the daily gross ecosystem productivity (GEP) and evapotranspiration. Seasonal change in shortwave albedo, as a result of the presence of mixed deciduous and coniferous species, was clearly evident. Albedo changes were comparable to the seasonal pattern of NEP. The dormant season lasts more than 6 months of the year at this station. This forest was a moderate sink of carbon over the measurement period. Annual values of GEP, ecosystem respiration (R), and NEP were 1075, 919, and 156±35gCm−2, respectively. [Copyright &y& Elsevier]

• Two new advanced configurations for CO 2 capture in pulp mill was investigated. • A rate-based model in ProMax® 4.0 was used for modeling the CO 2 capture process. • Techno-economic assessment was analyzed for the new advanced configurations. • The combined effect of carbon tax and CO 2 sales price on the NBSK price was analyzed. • CO 2 capture plant in pulp mill only led to a slight increase in the NBSK pulp price. This project study involves the techno-economic assessment of two new advanced configurations for amine-based carbon dioxide capture from a pulp mill. The newly proposed advanced configurations include advanced rich amine four split (ARA4S), and advanced rich amine three split with desorber inter-heating (ARA3S-DI) which is aimed at reducing carbon capture cost and carbon emissions. The rate-based model in ProMax® 4.0 was used for the simulation study while the flue gas was provided by a 365,000 air dry tonne of pulp (ADt Pulp) per annum pulp mill in British Columbia, Canada. Comparative analysis revealed that the Capture Cost (US$/tCO 2 and US$/ADt Pulp) of the 5 kmol/m3 MEA system was lowest for the conventional configuration, while for the 2 kmol/m3 AMP-3 kmol/m3 MEA blend it was lowest for the advanced rich amine 3-split with desorber inter-heating configuration. In addition, the Capture Costs of the MEA solution with a conventional configuration system is 8.7% higher than the AMP-MEA blend with advanced rich amine three split with desorber inter-heating configuration. Sensitivity analysis revealed that the combined effect of a carbon tax (US$ 40/tCO 2), CO 2 sales price (US$ 40/tCO 2) and advanced configuration only led to a slight increase (2.6% for MEA and 2.1% for AMP-MEA blend) in the price of the northern bleached softwood kraft pulp. With an even better-performing solvent system and process configuration, the price of NBSK pulp may not be affected given the indicated CO 2 tax and CO 2 price regime. [ABSTRACT FROM AUTHOR]