Geoscience Reference
In-Depth Information
I
NTRODUCTION
Carbon capture and sequestration (or storage)—known as CCS—is a
physical process that involves capturing manmade carbon dioxide (CO
2
) at its
source and storing it before its release to the atmosphere. CCS could reduce
the amount of CO
2
emitted to the atmosphere despite the continued use of
fossil fuels. An integrated CCS system would include three main steps:
(1) capturing CO
2
and separating it from other gases; (2) purifying,
compressing, and transporting the captured CO
2
to the sequestration site; and
(3) injecting the CO
2
in subsurface geological reservoirs or storing it in the
oceans. As a measure for mitigating global climate change, CCS has attracted
congressional interest and support because several projects in the United States
and abroad—typically associated with oil and gas production—are
successfully capturing, injecting, and storing CO
2
underground, albeit at
relatively small scales. The oil and gas industry in the United States injects
approximately 48 million metric tons of CO
2
underground each year to help
recover oil and gas resources (a process known as enhanced oil recovery, or
EOR).
1
Potentially, much larger amounts of CO
2
produced from electricity
generation—approximately 2.2 billion metric tons per year, over 40% of the
total CO
2
emitted in the United States from fossil fuels (see
Table 1
)—could
be targeted for large-scale CCS.
Table 1. Sources for CO
2
Emissions in the United States
from Combustion of Fossil Fuels
CO
2
Emissions
a
(millions of
metric tons) Percent of Total
E
lectricity generation 2,216.8 42%
Transportation 1,745.5 33%
I
ndustrial 777.8 15%
Residential 340.2 6%
Commercial 224.2 4%
Total 5,304.5 100%
Source: U.S. Environmental Protection Agency (EPA), Inventory of U.S. Greenhouse
Emissions and Sinks: 1990- 2010, Table ES-3 (2012); see http://epa.gov/climate
change/emissions/usinventoryreport.html.
a
CO
2
emissions in millions of metric tons for 2010; excludes emissions from
U.S. territories.
S
ources
