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Reducing NOx Emissions Using Energy Efficiency and Renewable Energy

Reducing emissions of nitrogen oxides using energy efficiency and renewable energy measures in Texas and including EE/RE measures as part of the State Implementation Plan strategy to meet the National Ambient Air Quality Standard for ozone.


Accurate quantification of emission reductions from energy efficiency and renewable energy (EE/RE) measures is challenging due to the complex nature of the electrical grid system. At any given time, it is impossible to determine exactly where on the electrical grid electricity comes from for any certain electrical user.

The United States Environmental Protection Agency's (EPA) 2004 guidance for claiming emission reductions from EE/RE presents additional challenges for taking direct credit for EE/RE measures, particularly in areas that have a NOx cap and trade program. The EPA guidance also requires additional commitments from states claiming reductions from EE/RE measures.

In the past, the TCEQ specifically included NOx emission reductions from EE/RE measures in the state implementation plan (SIP). In more recent SIP revisions, the TCEQ has not taken direct credit for EE/RE measures due to the challenges associated with quantification and EPA guidance.

EE/RE and the State Implementation Plan

Houston-Galveston-Brazoria Area

In the December 2002 HGB SIP revision , a methodology was developed with the support of the EPA and the Texas A&M Energy Systems Laboratory to estimate NOX reductions resulting from EE/RE measures.

The EPA’s Emissions and Generation Resource Integrated Database was used to spatially allocate the energy reductions in each of the eight HGB counties to electric generating units located in those counties or outside the HGB area. However, this methodology does not address the complication created from the NOX Mass Emissions Cap and Trade Program in the HGB area.

San Antonio Area

The November 2004 San Antonio Early Action Compact included 0.06 tons per day (tpd) of NOX emission reductions in 2007 from energy efficiency projects as a result of Senate Bill 5 (2001) and Senate Bill 7 (1999). 

Dallas–Fort Worth Area

The April 2005 DFW 5% Increment of Progress SIP revision included NOX emission reductions of 0.72 tpd in 2007 from EE/RE projects in the DFW 1997 eight-hour ozone nonattainment area.

The reductions were calculated based on electricity and natural gas usage reductions from implementation of the May 1, 2001 Texas Building Energy Performance Standards to single and multi-family residences in 2003.

These reductions also include less energy use because of energy efficiency measures implemented by local governments and utilities as reported to the Public Utility Commission of Texas and State Energy Conservation Office .

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