The energy penalty for post‐combustion carbon dioxide capture from fossil‐fired power plants can
be greatly reduced ‐ independently of the intrinsic heat of regeneration of the solvent used ‐ by
effective thermodynamic integration with the power cycle. Yet expected changes in electricity
generation mix and the current immaturity of post‐combustion capture technology are likely to
make effective thermodynamic integration throughout the operating life of such plants a challenging
objective to achieve because of a requirement for extensive part‐load operation and also for
matching to future technology improvements. Most previous published studies have, however,
focused on base‐load operation of the power cycle and the carbon dioxide capture plant and with
the assumption of a fixed technology.
For carbon dioxide capture‐ready plants the characteristics of the capture plant are also not known
when the plant is designed. The plant must operate initially without capture at a similar efficiency to
‘standard’ plants to be competitive. Capture‐ready plants then also need to be able to be retrofitted
with unknown improved solvents and to be capable of integration with a range of future solvents.
This study shows that future upgradability for post‐combustion capture systems can be facilitated by
appropriate steam turbine and steam cycle designs. In addition fossil‐fired power plants with postcombustion
capture may need to be able to operate throughout their load range with the capture
unit by‐passed, or with intermediate solvent storage to avoid the additional emissions occurring
when the absorption column is by‐passed. Steam cycles with flexible steam turbines can be
adequately designed to accommodate for part‐load operation with these novel operating conditions
and with rapid ramp rates.
Several approaches for effective capture‐ready pulverised coal and natural gas plants are also
described. These achieve identical performance before retrofit to a conventional plant with the
same steam conditions, but have the potential to perform well after capture retrofit with a wide
range of solvents, at the expense of only a small efficiency penalty compared to hypothetical plants
built with perfect foreknowledge of the solvent energy requirements. For existing plants that were
not made capture‐ready, and provided sufficient space is available and other physical limits are not
too constraining, ways to achieve effective thermodynamic integration are also discussed.