GREENIDGE MULTI-POLLUTANT CONTROL PROJECT Final Public Design Report Principal Author

The Greenidge Multi-Pollutant Control Project is being conducted as part of the U.S. Department of Energy’s Power Plant Improvement Initiative to demonstrate an innovative combination of air pollution control technologies that can cost-effectively reduce emissions of SO2, NOx, Hg, acid gases (SO3, HCl, and HF), and particulate matter from smaller coal-fired electric generating units (EGUs). The multi-pollutant control system includes a NOxOUT CASCADE hybrid selective non-catalytic reduction (SNCR) / in-duct selective catalytic reduction (SCR) system to reduce NOx emissions by ≥60%, followed by a Turbosorp circulating fluidized bed dry scrubbing system to reduce emissions of SO2, SO3, HCl, and HF by ≥95%. Mercury removal of ≥90% is also targeted via the co-benefits afforded by the in-duct SCR, dry scrubber, and baghouse and by injection of activated carbon upstream of the scrubber, if required. The technology is particularly well suited, because of its relatively low capital and maintenance costs and small space requirements, to meet the needs of coal-fired units with capacities of 50-300 MWe. There are about 400 such units operating in the United States that currently are not equipped with SCR or flue gas desulfurization (FGD) systems. These smaller units are a valuable part of the nation’s energy infrastructure, constituting more than 55 GW of installed capacity. However, with the onset of various state and federal environmental actions requiring deep reductions in emissions of SO2, NOx, and mercury, the continued operation of these units increasingly depends upon the ability to identify viable air pollution control retrofit options for them. The large capital costs and sizable space requirements associated with conventional technologies such as SCR and wet FGD make these technologies unattractive for many smaller units. The Greenidge Project aims to confirm the commercial readiness of an emissions control system that is specifically designed to meet the environmental compliance requirements of these smaller coal-fired EGUs. The multi-pollutant control system was installed and tested on the AES Greenidge Unit 4 (Boiler 6) by a team including CONSOL Energy Inc. as prime contractor, AES Greenidge LLC as host site owner, and Babcock Power Environmental Inc. as engineering, procurement, and construction contractor. About 44% of the funding for the project was provided by the U.S. Department of Energy, through its National Energy Technology Laboratory, and the remaining 56% was provided by AES Greenidge. AES Greenidge Unit 4 is a 107 MWe (Energy Information Administration net winter capacity, pre-project), 1953 vintage, tangentially-fired, reheat unit that is representative of many of the 400 smaller coal-fired units identified above. Start-up of the multi-pollutant control system was completed in March 2007, and the system was then demonstrated over an approximately 18-month period while the unit fired 2-4% sulfur eastern U.S. bituminous coal and co-fired up to 10% biomass. This Final Public Design Report is the last in a series of two reports describing the design of the multi-pollutant control facility that is being demonstrated at AES Greenidge. Its purpose is to consolidate for public use all available nonproprietary design and cost information on the Greenidge Multi-Pollutant Control Project. The Final Public Design Report builds upon the Preliminary Public Design Report, which was released in May 2007, to provide a comprehensive description of the final, as-built design of the demonstration facility at AES Greenidge. The capital cost and projected operating costs of the multi-pollutant control system are also discussed. The design and cost information summarized here is intended to help inform the decision making of generators seeking affordable air emissions control retrofit options for their smaller coal-fired units.