Environmental Engineering Reference
In-Depth Information
Section 5
CO 2 utilization
In this topic, we have focused on carbon capture and geological seques-
tration. In the sequestration sections, the CO 2 was viewed as a waste that
must be “put somewhere.” At present, there is a broad concern that any
process should focus on recycling rather than storing it as waste. This
has motivated many suggestions about a more “positive” use of CO 2
compared to storage in geological formations.
In Chapter 1, we already saw that a chemical conversion of CO 2 into
our universally useful product Dreamium™ would require so much
resource material that we would saturate any market or deplete any
supply.
Because petroleum is the present feedstock for production of many
chemicals, one can envision replacing petroleum with CO 2 as a feedstock
for carbon-containing chemicals. We have to realize, however, that only
7% of petroleum-derived carbon is used by the chemical industry; the
other 93% is used as fuel. Of course, any reduction in use of fossil fuels
is important and we most likely will need to use every available technol-
ogy to reduce CO 2 emissions, but the scope of using CO 2 as a source of
recyclable carbon for the chemical industry is too limited to offer a true
solution.
In our discussion on the use of CO 2 , we have not mentioned the idea
of recycling CO 2 back into a fuel. Interesting research is presently being
conducted on the catalytic conversion of CO 2 into CO, with particular
emphasis on the use of renewable energy sources for this conversion.
What are the consequences of such a scheme? If we have the technol-
ogy to convert CO 2 to CO using renewable energy sources, why not use
that renewable energy in the fi rst place and avoid using fossil fuels to
generate electricity? In generating electricity, we do not address trans-
portation fuels. In an energy economy in which renewable energy is
abundant, however, we can imagine upgrading CO 2 from Direct Air
Capture into a transportation fuel.
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