Large-Scale Geological Carbon Sequestration - Introduction to Carbon Capture and Sequestration - page 457

Section 1
Introduction

The implicit conclusion in Chapter 8 is that geological carbon sequestra-
tion will be a safe and effective approach for long-term storage of CO 2
and that CO 2 can be isolated indefi nitely from the atmosphere. In this
chapter, we focus on the following large-scale questions:

• Given the geological system and the properties of CO 2 , what is the

capacity for storing CO 2 , and on what factors does it depend?

• Are there negative environmental impacts related to carbon sequestra-

tion and if so how can they be mitigated?

• What methods will be used to monitor and account for CO 2 that is

sequestered deep underground?

We will address these questions from a continuum scale perspective.
This scale is loosely defi ned as being much larger than the pore scale in
a sedimentary rock, typically on the order of 100 microns (

m). We refer
to analyses and characterization as continuum scale because smaller
scale features and processes (for example, the shape of individual pores
and the connectivity of the pore network) are spatially averaged and
lumped into a homogeneous macroscopic continuum.
In Chapter 8, we introduced the time scales of the different pro-
cesses that are relevant for geological sequestration (see Figure 8.2.3 ).
This fi gure summarizes a wealth of understanding of the processes
related to carbon sequestration gleaned over more than a century's
worth of research in the earth sciences. In its abstraction, however, this
fi gure hides the rationale and evidence for its validity. Here we try to peel
away the multiple layers of abstraction to reveal a fuller picture of the
evidence and experience that indicates carbon sequestration is a highly
promising approach to mitigating CO 2 emissions.

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