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  • Elsevier  (4)
  • 1
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    Assessing model parameter uncertainties for rising velocity of CO2 droplets through experimental design (2012)
    Elsevier
    In:  International Journal of Greenhouse Gas Control, 11 . pp. 283-289.
    Details
    Publication Date: 2013-06-26
    Description: The risk and environmental impact assessments required for geological CO2 storage projects will have to rely on different types of numerical models, which will have to be calibrated and validated against measurements. Available measurements from ongoing demonstration projects are limited, hence it is necessary to turn to analog processes or laboratory experiments to estimate model parameters. In any case, parameter estimates will have uncertainties that will be important to assess when predicting future scenarios. We study a model for the rise velocity of droplets in the ocean, an important process sub-model for simulating gas seeps into marine waters. As the origin we use the parameters estimation study by Bigalke et al. (2010) based on a tank experiment. We illustrate how Linearized Covariance Analysis (LCA) can be used to assess the parameter uncertainties, and how to design a similar experiment that reduces these uncertainties. The linearity assumption underlying LCA is assessed using curvature measures. It is shown that up to ∼63% reduction in uncertainties is achieved by choosing the right droplet size distribution; by extending the range of droplet sizes to include larger droplets the uncertainties are reduced by another ∼88%.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    DOI: 10.1016/j.ijggc.2012.09.008
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    Assessing Model Uncertainties Through Proper Experimental Design (2013)
    Elsevier
    In:  Energy Procedia, 37 . pp. 3439-3446.
    Details
    Publication Date: 2013-11-05
    Description: This paper assesses how parameter uncertainties in the model for rise velocity of CO2 droplets in the ocean cause uncertainties in their rise and dissolution in marine waters. The parameter uncertainties in the rise velocity for both hydrate coated and hydrate free droplets are estimated from experiment data. Thereafter the rise velocity is coupled with a mass transfer model to simulate the fate of dissolution of a single droplet. The assessment shows that parameter uncertainties are highest for large droplets. However, it is also shown that in some circumstances varying the temperature gives significant change in rise distance of droplets.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    DOI: 10.1016/j.egypro.2013.06.233
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Layout of CCS monitoring infrastructure with highest probability of detecting a footprint of a CO2 leak in a varying marine environment (2015)
    Elsevier
    In:  International Journal of Greenhouse Gas Control, 37 . pp. 274-279.
    Details
    Publication Date: 2015-07-03
    Description: Highlights • A way to design a grid of sensor along the seafloor, with the purpose of detecting a leak, is presented. • The method relies site characterization, on local environmental statistics and on a detection threshold. • The method quantifies the probability of detecting a leak, and through an optimization procedure finds the optimal layout. • The cost function can be extended to include other constraints, such as cost or need to cover vulnerable areas. Abstract Monitoring of the marine environment for indications of a leak, or precursors of a leak, will be an intrinsic part of any subsea CO2 storage projects. A real challenge will be quantification of the probability of a given monitoring program to detect a leak and to design the program accordingly. The task complicates by the number of pathways to the surface, difficulties to estimate probabilities of leaks and fluxes, and predicting the fluctuating footprint of a leak. The objective is to present a procedure for optimizing the layout of a fixed array of chemical sensors on the seafloor, using the probability of detecting a leak as metric. A synthetic map from the North Sea is used as a basis for probable leakage points, while the spatial footprint is based on results from a General Circulation Model. Compared to an equally spaced array the probability of detecting a leak can be nearly doubled by an optimal placement of the available sensors. It is not necessarily best to place the first in the location of the highest probable leakage point, one sensor can monitor several potential leakage points. The need for a thorough baseline in order to reduce the detection threshold is shown.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    DOI: 10.1016/j.ijggc.2015.03.013
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Detection and quantification of CO2 seepage in seawater using the stoichiometric Cseep method: Results from a recent subsea CO2 release experiment in the North Sea (2021)
    Elsevier
    Details
    Publication Date: 2024-02-07
    Description: Carbon Capture and Storage (CCS) is a potential significant mitigation strategy to combat climate change and ocean acidification. The technology is well understood but its current implementation must be scaled up nearly by a hundredfold to become an effective tool that helps meet mitigation targets. Regulations require monitoring and verification at storage sites, and reliable monitoring strategies for detection and quantification of seepage of the stored carbon need to be developed. The Cseep method was developed for reliable determination of CO2 seepage signal in seawater by estimating and filtering out natural variations in dissolved inorganic carbon (C). In this work, we analysed data from the first-ever subsea CO2 release experiment performed in the north-western North Sea by the EU STEMM-CCS project. We successfully demonstrated the ability of the Cseep method to (i) predict natural C variations around the Goldeneye site over seasonal to interannual time scales; (ii) establish a process-based baseline C concentration with minimal variability; (iii) determine CO2 seepage detection threshold (DT) to reliably differentiate released- CO2 signal from natural variability and quantify released- CO2 dissolved in the sampled seawater. DT values were around 20 % of the natural C variations indicating high sensitivity of the method. Moreover, with the availability of DT value, the identification of released- CO2 required no preknowledge of seepage occurrence, but we used additional available information to assess the confidence of the results. Overall, the Cseep method features high sensitivity, automation suitability, and represents a powerful future monitoring tool both for large and confined marine areas.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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