Energy and Electricity - Introduction to Carbon Capture and Sequestration - page 4

Box 1.1.1 ( Continued )
The figure shows the phase diagram of carbon dioxide. We see the triple point at
p = 5.18 bar (518 kPa) and T = − 56.6 ° C where the solid (s), liquid (l), and gas (g) phases
coexist. The line connecting the triple point with the critical point (p c = 73.8 bar and
T c = 31.1 ° C) is the vapor-liquid coexistence line. At pressures above this line CO 2
exists as a liquid and below the line it exists in the gas phase. At 1 atmosphere (1.013
bar) CO 2 becomes a solid below 194.7 K.
Of special interest for carbon capture and sequestration is the supercritical
region above the critical temperature. At these conditions the CO 2 is referred to as in
the fluid (f) phase. In this fluid phase CO 2 may be pumped most easily through pipe-
lines because there is no liquid-vapor coexistence. A critical temperature near ambient
conditions also implies that one can compress CO 2 gas to a dense fluid without it
going through a phase transition that may consume more energy.
many other factors that are not addressed in traditional science or engi-
neering courses. These topics are a context for CCS, and understanding
them is essential to appreciating the technical directions and choices
that are made in CCS research.
As CO 2 plays a central role in the text, we have summarized some of
the properties of carbon dioxide in Box 1.1.1 .
Section 2
The number of carbon atoms
and still counting…
Chemists like to identify themselves with molecules. If anything, the
holy grail of a chemist is a perfect intuition on how molecules would
react in different environments. In the later chapters we will see some