PhD ThesisCarbon Capture and Storage (CCS) is recognised as one of a suite of solutions
required to reduce carbon dioxide (CO2) emissions into the atmosphere and
prevent catastrophic global climate change. In CCS schemes, CO2 is captured
from large scale industrial emitters and transported, predominantly by pipeline,
to geological sites, such as depleted oil or gas fields or saline aquifers, where it
is injected into the rock formation for storage.
The requirement to develop a robust Quantitative Risk Assessment (QRA)
methodology for high pressure CO2 pipelines has been recognised as critical to
the implementation of CCS. Consequently, failure frequency and consequence
models are required that are appropriate for high pressure CO2 pipelines. This
thesis addresses key components from both the failure frequency and
consequence parts of the QRA methodology development.
On the failure frequency side, a predictive model to estimate the failure
frequency of a high pressure CO2 pipeline due to third party external
interference has been developed. The model has been validated for the design
requirements of high pressure CO2 pipelines by showing that it is applicable to
thick wall linepipe. Additional validation has been provided through comparison
between model predictions, historical data and the existing industry standard
failure frequency model, FFREQ.
On the consequences side, models have been developed to describe the
impact of CO2 on people sheltering inside buildings and those attempting to
escape on foot, during a pipeline release event. The models have been coupled
to the results of a dispersion analysis from a pipeline release under different
environmental conditions to demonstrate how the consequence data required
for input into the QRA can be determined. In each model both constant and
changing external concentrations of CO2 have been considered and the toxic
effects on people predicted. It has been shown that the models can be used to
calculate safe distances in the event of a CO2 pipeline release.National Gri
