Annex 1
COMPARISON OF COAL-BASED CO2 CAPTURE
TECHNOLOGIES BASED ON RECENT IEA GHG STUDIES
CO2 capture is usually the main cost
in a CCS scheme so the choice of capture technology is important.
Comparisons between the costs for different options can be difficult,
however, as the following table illustrates. Even though these
studies were undertaken using standard IEA GHG assumptions (and
the latter two by mainly the same team) absolute capital costs
are not entirely consistent: IGCC appears to have the same cost
as pulverised coal rather than the 10-20% more that is widely
thought to be the case and an identical pulverised coal plant
has different prices in US dollars for the last two studies due
to exchange rate fluctuations. But this is recognised in the wide
+/-30% error margins quoted for capital costs. It is also why
power plants are bought by tender!
The yellow shaded areas show the performance
figures and normalised relative costs, which are likely to be
more reliable indicators. Perhaps surprisingly, the performance
for all the options is very similar. The Texaco IGCC plant has
a small efficiency drop for capture, but still has a lower absolute
efficiency value. The incremental capital cost for capture on
IGCC plants is around 30% extra against 50% for post combustion
and oxyfuel, but this would be offset by an extra 10-20% initial
capital cost for IGCC. Other factors would therefore probably
be more influential than cost in choices between these alternative
capture options for new coal plant.
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