Under a DOE NETL cooperative agreement, ADA-ES is working in partnership with a number of power generators and vendors on a field evaluation program of injecting sorbent, including powdered activated carbon (PAC), upstream of existing particulate control devices. The objective of this program is to obtain the necessary information to assess the costs of controlling mercury from coal-fired plants using dry injection. The economics will be developed based on various levels of mercury control. These tests represent the first time that PAC has been injected on such a large scale and continuously for periods of several weeks. Three of the four full-scale tests scheduled in this program have been completed. Final results from the evaluation of carbon injection into COHPAC at Alabama Power's Plant Gaston Unit 3 burning a bituminous coal and from tests on an electrostatic precipitator (ESP) at Wisconsin Electric's Pleasant Prairie Power Plant Unit 2 burning a Powder River Basin (PRB) coal will be presented. Preliminary results from testing on an ESP with a bituminous coal will also be discussed. Tests at each site included a series of parametric tests on different carbons and several injection concentrations, and a long-term test at optimized conditions. Impact of sorbent injection on the particulate control devices was also evaluated. (C) 2004 Published by Elsevier B.V.