Heat-rate basis: recovered HRSG/steam-side losses improve heat rate fractions of a percent — small in %, large in absolute fuel+carbon on baseload hours.
From our guide: Decarbonizing Power — full context, charts and sources there.
Boilers, kilns, heat exchangers, valves and steam lines lose energy continuously. Inzonex makes patented (UK GB2508992.1) removable modular insulation — snap-fastened covers engineered per temperature tier, not generic off-the-shelf jackets: