Environmental Engineering Reference
In-Depth Information
for interest in IGCC is that it is easier to capture the
carbon dioxide if it is to be captured and stored away
(see
Section
).
The shift toward gas for electricity generation, one of
the four options to reduce emission mentioned at the
beginning of this chapter, is happening in the United
States because the balance of fuels used for generation
of electricity has changed signi
.
cantly since the end of the
year
finished.
As mentioned earlier, the contribution of coal has fallen
to about
when the
rst edition of this topic was
% and is still falling, whereas that of natural
gas has risen to
% and is still rising. Nuclear energy
stays at about
%.
However, the renewables have two parts: old-fashioned
renewables such as hydroelectric dams and burning bio-
mass, and newer ones like wind and solar. There is much
in the news about the large addition to capacity by wind
and solar, but be careful here. Typical average output of
land-based wind farms in the United States is only about
%, and the renewables are about
% of capacity, while for solar it is only about
%in
the best places such as the Southwest. In
, the old-
fashioned renewables contributed about
%, while wind
and solar added
%. The reduction of CO
emissions in
the United States is mainly due to the move away from
coal toward natural gas.
The surge in natural gas use for the generation of
electricity is mainly a US phenomenon because of a big
addition to supply from the new technique of fracking.
Unlike oil which is easy to move around the world, gas is
hard and expensive to move so that the world price for gas
does not re
ect the highest-cost sources of supply. In the
United States, gas costs about
$
per million BTU, in
