What is an avoided emission?
Avoided emissions would have been emitted under a business as usual scenario but were avoided as a result of the implementation of an emission reduction project. For sequestration, the use of avoided emissions takes into consideration (1) the reduced net efficiency of the fossil fuel conversion process from the parasitic load of the carbon dioxide capture, compression, transport, and storage systems, and (2) the fact that 100% of exhaust carbon dioxide is not captured because of engineering limitations of current capture technology. Assessing carbon sequestration systems on an avoided emissions basis is the proper method for producing results that can be compared to nuclear, renewables, and other greenhouse gas emissions reduction options.
Avoided emissions are those emissions that are not produced (are avoided) by using non-emitting technologies or by capturing and sequestering emissions from an emitting source. For the fossil energy industry, avoided emission measures reduction in CO2 and other greenhouse gas emissions but also takes into account the reduced capacity of power plants caused by the addition of a CO2 capture and sequestration system. Avoided emissions are calculated from a baseline that describes what the emissions would have been without carbon capture and sequestration. For capture and sequestration purposes, calculating avoided emissions takes into consideration 1) the reduction in power plant efficiency resulting from the extra energy load of the CO2 CCS system, and 2) the fact that not all exhaust CO2 can be captured with current technology. Assessing carbon capture and sequestration systems on an avoided emissions basis is the best way to show results that can be compared to nuclear, renewables, and
