2012 Progress Report: Analysis of Dynamic, Flexible NOx and SO2 Abatement from Power Plants in the Eastern U.S. and Texas

EPA Grant Number: R835216
Title: Analysis of Dynamic, Flexible NOx and SO2 Abatement from Power Plants in the Eastern U.S. and Texas
Investigators: McDonald-Buller, Elena , Allen, David T. , Webster, Mort D.
Current Investigators: McDonald-Buller, Elena , Allen, David T. , Craig, Michael T. , Kimura, Yosuke , McGaughey, Gary , Webster, Mort D.
Institution: The University of Texas at Austin , Massachusetts Institute of Technology
Current Institution: The University of Texas at Austin , Massachusetts Institute of Technology , Pennsylvania State University
EPA Project Officer: Chung, Serena
Project Period: June 1, 2012 through May 31, 2016
Project Period Covered by this Report: June 1, 2012 through May 31,2013
Project Amount: $500,000
RFA: Dynamic Air Quality Management (2011) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Air


Federal standards for fine particulate matter and tropospheric ozone have become increasingly stringent over the past several decades. States preparing attainment plans will be challenged with the higher marginal costs of additional permanent or annual emissions reductions in the future. This study is developing methods for evaluating the air quality impacts and cost-effectiveness of time-differentiated trading of nitrogen oxides (NOx) and sulfur dioxide (SO2) from electric generation units (EGUs). Two markets are serving as case studies: the Electric Reliability Council of Texas (ERCOT), which is an intra-state grid, and the Pennsylvania-New Jersey-Maryland (PJM) grid, which is an inter-state grid. The project is examining the following hypotheses:
  1. Time-differentiated dispatching strategies lead to reductions in ozone and fine particulate matter concentrations and exposure that are comparable to other technologies.
  2. Hybrid scenarios that combine time-differentiated trading and other technologies within a single electric grid provide more cost-effective control and greater air quality benefits than a single approach.
  3. The effectiveness of emissions trading strategies is sensitive to the selection of an air quality impact metric.
  4. An emissions pricing strategy can be developed that optimizes the joint abatement of multiple pollutants by considering the integrated impact.

Progress Summary:

The first year of the project has focused on three activities: (1) development of the air quality modeling platform and evaluation of model performance in the ERCOT and PJM grids; (2) development of an electric power dispatching and emissions model for the ERCOT grid; and (3) reconciliation of emissions data for the ERCOT grid. The project utilizes 2005 annual air quality modeling with the Comprehensive Air Quality Model with Extensions (CAMx) that was developed by the U.S. EPA for analyses of the Transport Rule and Cross-State Air Pollution Rule (CSAPR). A number of modifications to the model configuration and emissions inventories were made for the purposes of this work. A model performance evaluation that compared modeled and measured ambient concentrations of ozone and PM2.5 components at monitoring sites located within the ERCOT and PJM grids was conducted.
A hybrid power plant dispatch and control technology installation model has been developed that calculates NOx and SO2 emissions from power plants under user-entered dynamic NOx and/or SO2 pricing. Choices are made as to whether to install air pollution control technology based on dispatching scenarios under a zonally constrained unit commitment model for a period of time representative of the year’s summer demand profile under a given pricing regime for NOx and/or SO2. Following installation decisions, emissions profiles are calculated via dispatching with the same unit commitment model over one or more seasons. Initial scenarios are exploring the effects of dynamic emissions pricing on electricity dispatching and competitive decisions regarding technology installation in the ERCOT grid based on the EPA's eGRID 2007 database and, where possible, CEMS data for 2005. Selective catalytic reduction (SCR) is the control technology currently considered. The hybrid dispatch model has been run weekly over May through October of 2005. Hourly emissions for each plant are processed with the Sparse Matrix Operator Kernel Emissions (SMOKE) model for use in CAMx. Because the hybrid modeling and eGRID provided estimated NOx and SO2 emissions at the generator level, each ERCOT generator required mapping to an appropriate emission stack (or stacks) in the elevated point source emission inventory used by SMOKE.
Preliminary emissions scenarios have been developed using the electric sector model to explore (1) the impact of multi-pollutant dynamic pricing applied to NOx and SO2, and (2) the tradeoffs among alternative regulatory designs. Initial results of multi-pollutant scenarios show that under a dynamic NOx and SO2 pricing regime, the average cost of SO2 emission reductions is lower than under a stand-alone SO2 price, but the same is not true for NOx emission reductions. This suggests that a dynamic NOx price has greater co-benefits in reducing SO2 emissions than an SO2 price has in reducing NOx emissions. Initial results from comparing regulatory designs demonstrate that mandating technology installation can have greater emissions reductions but at higher costs, as compared to dynamic pricing where individual plants decide whether or not to install controls. Whether the additional cost is justified cannot be known until the full integrated analysis, including atmospheric chemistry, is performed to investigate the impacts on ozone concentrations. This analysis is part of the future activities described below.

Future Activities:

The second year of the project will continue to focus on the effects of dynamic emissions pricing of NOx and SO2, individually and in combination, on electricity dispatching and competitive decisions regarding technology installation (SCR and SNCR) in the ERCOT grid. Scenarios will consider the region-wide emissions reductions from EGUs that are achievable and their resulting impact on air quality, as well as dynamic pricing on days that exceed a threshold concentration for a single pollutant (i.e., either ozone or fine particulate matter) versus multiple pollutants (both ozone and fine particulate matter). The sensitivity of results to a range of air quality metrics will be considered, and for a subset of relevant metrics, an attempt will be made to develop an integrated approach capturing the combined impacts associated with multiple pollutants. Simulation of the PJM grid with the hybrid power plant dispatch and control technology installation model will also be initiated this upcoming year.

Journal Articles:

No journal articles submitted with this report: View all 11 publications for this project

Supplemental Keywords:

Electricity generation, emissions trading, ozone, particulate matter, Texas, CAMx

Progress and Final Reports:

Original Abstract
2013 Progress Report
2014 Progress Report
Final Report