Do you mean capture of carbon dioxide specifically. Most plants are not equipped with CO2 capture options but recently there are several technologies available and carbon capture and storage is a good option that is being considered.
The easiest one is creation of algal ponds through which flue gas can be bubbled and CO2 is absorbed by algae. A more complicated one are CO2 capture systems developed by several companies Mitsubishi electrics has also developed such a system which captures low pressure co2 emitted from plants and pressurize's it for use in heating or CCS or EOR.
CCS technologies are currently under development. moreover, from an economic point of view, if Carbon emissions trading is not taken into account, the feasibility of the investment becomes tougher.
on the other hand, WHR technologies maximize the overall efficiency of the plant decreasing the fuel consumption, thus GHG emissions. for istance, that's what happened in combined cycle power plants.