Environmental Engineering Reference
In-Depth Information
deep ocean, transporting it there either by pipeline or as
a liquid in a ship. This one doesn
twork.Theother
puts it under the surface in depleted oil and gas reser-
voirs or in what are called deep saline aquifers. These
contain mineral-laden waters deep underground that
are not connected to fresh water supplies. This one
might work.
The issue is, does the CO
stay where you put it? For
the oceans we know the answer and it is no. Surface
waters in the oceans are slowly carried to the deeps and
deep waters are slowly transported to the surface. How
fast the process runs depends on the depth. The IPCC
Special Report estimates that if we deposit
'
'
worth of CO
produced in this century at a depth of about
years
% would have come back
out by the end of the next century. Deeper is better, and if
it were put at a depth of
feet in the ocean, about
feet only
% would have
come back out.
Storage underground on land raises two issues. The
does the CO
stay
where you put it? The second is the capacity of the
underground sites. The IPCC Special Report estimates
that, worldwide, depleted oil and gas reservoirs can
store between
first is the same as for the oceans
-
billion tonnes of CO
while
the deep saline aquifers can store between
and
and
billion tonnes. The business-as-usual scenario
would give about
billion tonnes for the total emis-
sions in this century, and that much is a tight
fit for what
we know of the potential storage sites. In addition, the sites
are not uniformly distributed around the world. There
seem to be lots of deep saline aquifers under the United
States and few under China, the two largest emitters.
