NOx pollutants do not form in significant amounts at temperatures below 2800 degrees Fahrenheit. Initially the focus of NOx controls was on finding ways to burn fuel in stages. "Low-NOx" burners use a staged combustion process, which uses a lower flame temperature during some phases of combustion to reduce the amount of NOx that forms. These burners also limit the amount of air in the initial stages of combustion, when the nitrogen naturally occurring in the coal is released, so that there is less oxygen present to bond with the nitrogen. As of 2006, the Department of Energy estimated that approximately low-NOx burners were installed on conventional coal plants as of 2006. These burners can reduce nitrogen oxide emissions by 40 percent or more. In the case of fluidized bed technology, combustion occurs at temperatures of 1,400 to 1,700 degrees Fahrenheit, lower than the threshold at which nitrogen oxide pollutants form.<ref name="doe"/>
In 2005, the EPA passed the [[Clean Air Interstate Rule]], which requires a 61 percent cut in nitrogen oxide emissions from power plants by 2015.<ref>[http://www.columbusdispatch.com/live/content/local_news/stories/2008/04/14/Powerfills.ART_ART_04-14-08_B1_FF9TI0U.html?sid=101 “Utilities amassing landfills: Tougher air standards send tons of plants' sludge, coal ash into ground”], ''Columbus Dispatch'', April 14, 2008.]</ref> This level of emissions reduction requires a different technology. Selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR) both convert NOx into water (H<sub>2</sub>O) and nitrogen (N<sub>2</sub>). SCR is capable of reducing NOx emissions by approximately 90 percent. SNCR is a simpler and less expensive technology than SCR, but it also provides a lower level of NOx reduction.<ref>[http://www.de-nox.com/SCR.htm Selective catalytic reduction,] De-NOx Technologies, accessed November 2008.</ref><ref>[http://www.de-nox.com/technology.htm Selective non-catalytic reduction,] De-NOx Technologies, accessed November 2008.</ref><ref>[http://www.tva.gov/environment/air/nox.htm Nitrogen Oxides,] Tennessee Valley Authority, accessed November 2008.</ref>
==Coal waste==
According to the U.S. Department of Energy:
::"The Clean Coal Power Initiative (CCPI) is a 10-year, $2 billion program designed to support the Clean Coal Technology Roadmap milestones with the government providing up to 50 percent of the cost of demonstrating a range of promising technologies. CCPI is implemented through a series of five solicitations over the 10-year period, two of which have already been issued and selections made. CCPI provides the means to demonstrate those technologies proven through R&D to have commercial potential. Demonstrations are at a commercial scale in actual operating environments, which is essential to moving them to the threshold of commercialization."<refname="init">[http://www.netl.doe.gov/technologies/coalpower/cctc/ccpi/index.html "Clean Coal Power Initiative,"] National Energy Technology Laboratory website, accessed April 2008</ref>
As of April, 2008, 8 projects were active and 4 had been withdrawn.<refname="init"/>According Department of Energy Fact Sheet, the multi-year Clean Coal Power Initiative (CCPI), "is driven by private-sector-proposed projects in response to a government solicitation. Potential applicants include technology developers, service corporations, R&D firms, energy producers, software developers, academia, and other interested parties. The private sector cost share must be at least 50 percent. Funding is awarded to applicants, selected as a result of these open competitions, who can rapidly move promising new concepts to a point where private-sector decisions on deployment can be made." <ref name="netl">[http://www.netl.doe.gov/technologies/coalpowerpublications/cctcfactsheets/ccpiprogram/indexProg052.html pdf "Clean Coal Power InitiativeProgram Facts,"] National Department of Energy Technology Laboratory websitefact sheet, accessed April 2008(PDF File)</ref>
According Department of Energy Fact Sheet, the multi-year Clean Coal Power Initiative (CCPI), "is driven by private-sector-proposed projects in response to a government solicitation. Potential applicants include technology developers, service corporations, R&D firms, energy producers, software developers, academia, and other interested parties. The private sector cost share must be at least 50 percent. Funding is awarded to applicants, selected as a result of these open competitions, who can rapidly move promising new concepts to a point where private-sector decisions on deployment can be made." <ref>[http://www.netl.doe.gov/publications/factsheets/program/Prog052.pdf "Program Facts,"] Department of Energy fact sheet, accessed April 2008 (PDF File)</ref> Round I participants:<ref>[http://www.name="netl.doe.gov/publications/factsheets/program/Prog052.pdf "Program Facts,"] Department of Energy fact sheet, accessed April 2008 (PDF File)</ref>
* Great River Energy, Underwood, ND - Increasing Power Plant Efficiency–Lignite Fuel Enhancement
* NeuCo, Inc., Boston, MA - Demonstration of Integrated Optimization Software at the Baldwin Energy Complex
* Wisconsin Electric Power Co., Milwaukee, WI - TOXECON Retrofit for Mercury and Multi-Pollutant Control on Three 90 MW Coal-Fired Boilers
Round II participants:<ref>[http://www.name="netl.doe.gov/publications/factsheets/program/Prog052.pdf "Program Facts,"] Department of Energy fact sheet, accessed April 2008 (PDF File)</ref>
* Excelsior Energy, Inc., Minnetonka, MN - Mesaba Energy Project
* Pegasus Technologies, Incorporated, Chardon, OH - Mercury Specie and Multi-Pollutant Control