Return to NETL Home
Go to US DOE

News Release

Release Date: November 7, 2005

DOE-Funded Technology Slashes NOx, Costs in Coal-Fired Cyclone Boiler
Utility Reconsiders Plans to Install Standard NOx-control Technology After Successful Field Test

PITTSBURGH, PA - A new technology recently evaluated on a type of coal-fired boiler notorious for generating the air pollutant known as NOx was found to reduce NOx formation by 90 percent at about half the cost of current technologies.

Known as the Advanced Layered Technology Approach, or ALTA, the technology was field-tested this summer at AmerenUE’s Sioux Unit 1 Station near St. Louis, Mo., using a blend of Powder River Basin and Illinois coals in a 500-megawatt cyclone boiler. The results have led the utility to reconsider its plans to install another NOx-control technology, called selective catalytic reduction, in favor of ALTA. Ameren is now evaluating full-scale implementation of ALTA technology in both 500-megawatt units at the Sioux Power Plant, with potential installation anticipated in 2006.

Sioux Power Plant

Ameren’s Sioux Unit 1 has demonstrated the first in-furnace control technology that achieves NOx emissions below 0.15 pounds per million Btu on a coal-fired cyclone boiler—a 90 percent reduction over the unit’s baseline NOx emissions—at half the cost of current technologies. Ameren is now reconsidering its plans to install standard NOx-control technology in favor of ALTA.

The field test is one of five advanced NOx-control projects recently awarded contracts through the Department of Energy’s Innovations for Existing Plants Program, managed by the National Energy Technology Laboratory. The overall goal of the program is to enhance the efficiency and environmental performance of existing coal-fired power systems as part of DOE’s commitment to clean coal technology.

ALTA uses a strategic combination of overfire air, rich reagent injection, and selective non-catalytic reduction processes in the boiler to reduce NOx formation and ammonia slip. The ALTA technology also shares equipment such as tanks, pumps, and injection components between the selective non-catalytic reduction and rich reagent injection systems to reduce the capital costs for installation and operation.

In short-term field testing, the Sioux Unit 1 demonstrated for the first time that an in-furnace control technology can achieve NOx emissions below 0.15 pounds per million Btu on a coal-fired cyclone boiler. With the ALTA technology, NOx emissions were 0.12 pounds per million Btu firing the typical blend of 80 percent Powder River Basin coal and 20 percent Illinois coal, and they were as low as 0.165 pounds per million Btu firing 100 percent Illinois coal.

RRI Modeling

Modeling had shown that the injection of an ammonia-rich chemical compound would reduce NOx emissions in a cyclone boiler from 1.2 to 0.35 pounds per million Btu. The same results have now been obtained in the field-testing of a standard-size unit. Combining this technology with a selective non-catalytic reduction process further pushed emissions down, to 0.15 pounds per million Btu.

The 0.12 pounds per million Btu NOx level represents a 90 percent reduction from the Sioux Unit 1 pre-overfire air baseline emissions. The ALTA technology results in emission levels that will help to meet the EPA’s recently announced Clean Air Interstate Rule for NOx limits.

The field test was a collaborative effort led by Reaction Engineering International (REI) working with Ameren, EPRI, and FuelTech, Inc. Rich reagent injection was co-developed by EPRI and REI with funding from DOE-NETL. It is licensed to REI, who in turn has sublicensed it to FuelTech Inc. and Combustion Components Associates.


Contact: David Anna, DOE/NETL, 412-386-4646