Control of mercury emissions from coal-fired power plants: a preliminary cost assessment and the next steps for accurately assessing control costs

Mercury emissions from coal-fired power plants have been extensively evalua ted for nearly 10 years to determine possible regulation by the Environment al Protection Agency (EPA). Under a court order, a determination will be ma de on whether it is appropriate and necessary to regulate toxic air polluta nt emissions (focusing on mercury) from coal-fired utility boilers by Decem ber 15, 2000, If it is determined that regulations are necessary, then the regulatory process will have a fixed timetable. A proposed regulation will be due no later than December 15, 2003, and promulgated no later than Decem ber 15, 2004. The utility industry regulatory compliance must be in place b y December 2007 since the Clean Air Act requires that sources come into com pliance with Maximum Achievable Control Technology (MACT) 3 years after pro mulgation of the regulations. While it is recognized that the main driver f or regulation is the potential risk to human health and that this risk is c urrently being examined by a number of health-based organizations, the actu al form of any regulation would likely be dependent upon the availability o f cost-effective control technologies. Furthermore, the diverse nature of t he coal-fired utility industry will likely limit the applicability and cost -effectiveness of any given technology for the current boiler population. In light of a potential regulatory determination, this paper examines a few control options that warrant further consideration. A preliminary assessme nt of mercury capture technologies and associated costs is conducted for so rbent injection technology. Sorbent-based technologies that may be amenable for mercury control include: (1) sorbent injection with and without spray cooling upstream of existing particulate control devices (i.e., electrostat ic precipitators and fabric filters): and (2) sorbent injection with and wi thout spray cooling associated with additional control devices designed to augment particulate collection in a primary particulate control device. Imp ortant design criteria for each of the control systems are critically asses sed for operability, maintainability, and reliability, with the projected i mpacts of the control system on power plant operations being evaluated. The sorbent-based technology discussed in this paper focuses on the injection of activated carbon associated with the various particulate control devices used in the utility industry. The paper also addresses the next steps and revisions needed to accurately assess possible cost impacts to the utility industry as the mercury control options mature in their development. (C) 20 00 Published by Elsevier Science B.V. All rights reserved.