MWCOG
 

Using a Time-Matched 

Hourly Marginal Emissions 

Tool in Metropolitan 

EPA Webinar on Washington 

Quantifying Emission 

Impacts of Clean 

Energy Initiatives Jeff King, MWCOG jking@mwcog.org 

Colin High, RSG Inc. chigh@rsginc.com 
 

 

 

 

 

 

 

Contents
 

Jeff King, MWCOG: (Slides 2-6) 

•MWAQC Overview 

•EERE as a Control Measure for the Ozone and PM SIPs 

•Moving Beyond the Voluntary Bundle & Success Factors 

Colin High, RSG Inc.: (Slides 7-15 ) 

•Tools for Measuring Avoided Emissions from EERE 

•RSG TMM Model – Introduction 

•TMM Model Overview, Methodology & Details 

•Comparison of Emission Rates 

•MWCOG Avoided Emissions Calculator & Lessons learnt 

2 
 

 

 

 

 

 

 

 

Metropolitan Washington Air Quality Committee (MWAQC) 

Created, 1992 

•	 Metropolitan Washington Air Quality 

Committee conducts air quality 

planning for the Washington 

nonattainment region. 

•	 MWAQC includes state agency 

representation from Maryland, DC, and 

Virginia 

•	 Local Government representation 

•	 Supported by Technical Advisory 

Committee (TAC) and Air and Climate 

Public Advisory Committee (ACPAC) 

•	 MWAQC is staffed by the Metropolitan 

Washington Council of Governments 

3 
 

 

 

 

 

 

 

 

EERE as a Control Measure for the Ozone and PM SIPs
 

•	 Wind Power Purchase in 1-hour Ozone SIP 

•	 Expanded Program for 8-hour Ozone SIP and 

PM2.5 SIP 

–	 More wind, added Renewable Portfolio Standard, 

and Energy Efficiency, including Green Buildings 

and LED Traffic Signals 

•	 Followed EPA Voluntary Measures Guidance
 

•	 Included as part of the Voluntary Bundle 

•	 Needed Tool to Estimate Emission Reduction 

from the Energy Impact 

4 
 

 

 

 

 

Moving Beyond the Voluntary Bundle
 

New State Energy and Climate Plans Involve
 

Significant New Energy Initiatives
 

Maryland 

–	 EmPower Maryland 

–	 Maryland Climate Action
 

Plan
 

– RGGI
 

The District
 

–	 District Sustainable Energy Utility 

–	 DC Climate Plan 

Virginia 

–	 Virginia Energy Plan 

–	 Virginia Electric Utility 

Integrated Resource 

Planning Law 

–	 Virginia Climate Plan 

5 
 

 

 

 

 

 

 

 

Success Factors
 

•	 State and Local Leadership 

•	 Enabling Regulations and Guidance 

–	 NOx SIP Call/CAIR/CATR (action needed) 

–	 EPA Voluntary Measures Guidance 

–	 EPA Roadmap (pending) 

•	 Commitment to Tracking and 

Reporting 

•	 NEEP EM&V Forum 

•	 DOE/NREL: Funding and Technical 

Assistance Grant 

•	 MWCOG Avoided Emission Calculator
 

6 
 

 

 

 

 

Tools for Measuring Avoided Emissions from EERE
 

•	 Accurate avoided emissions measurement requires the

use of a marginal emissions model that takes account of 

the time variability of EERE impacts on the grid. 

•	 The model must be applied to the power market area that

is impacted by the EERE changes 

•	 MWCOG used the RSG Time Matched Marginal (TMM)

Emission model. This was supported by DOE funding. 

•	 RSG built a calculator based on the TMM model that 

enables MWCOG and local governments to quickly

evaluate the avoided emissions from the most common 

EERE measures in the region. New measures can easily be

added to the calculator. 

7 
 

 

 

 

 

 

What is the RSG TMM Emissions model ?
 

•	 The TMM model is an 8760 hour historical dispatch model that

captures the economic dispatch and reliability decisions made by the

electric grid system operator in order to calculate avoided emissions

from EERE on an hourly basis. 

•	 The time matching is based on actual or simulated 8760 hour energy 

savings or generation data from EERE projects or programs in a power

market. 

•	 The model is available for all US power markets, states and regions. 

•	 The model has been applied to the analysis of more than 250 EERE

projects and programs in the US. 

•	 Model applications include almost all existing and new EERE

technologies, nuclear power plants, IGCC coal plants with carbon

sequestration, battery storage, flywheels and electric vehicle

charging. 

8 
 

 

 

 

 

TMM Model Overview
 

0 

10 

20 

30 

40 

50 

Generation 

in GWh 

Peak 

Intermediate 

Base 

Oil 

Gas 

Coal 

Oil 

Gas 

Coal 

Nuclear 

Oil 

Gas 

The TMM model calculates the grid marginal emission rates from fossil 

fueled units hour by hour for every day of the year. 

The chart shows the Base, Intermediate and Peak Load on a typical day 

and the unit fuel mix in a Mid-Atlantic Power Market. 

9 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TMM Model Methodology
 

1.	 IDENTIFY the marginal fossil fuelfired units in a power market for 

each hour by using a load-following 

algorithm to calculate the 

incremental marginal emission rates. 

2.	 COMPILE an annual hourly load 

profile of the energy savings or 

generation for the EERE technology 

and region under study. 

3.	 “TIME-MATCH” the EERE hourly load 

profile against the marginal emissions 

profile on an hourly basis. 

4.	 CALCULATE total avoided emissions 

from annual savings or generation 

on an hourly, monthly or annual 

basis. 

Matching the changes in energy savings or generation provides greater precision in measurement. 

10 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

TMM Model Details
 

Measures the operational changes in air emissions resulting from changes in load or 

generation on the regional grid. 

•	 Based on publicly available data from US EPA, US DOE - EIA, ISOs and industry sources. 

•	 Emissions monitoring data for every hour of the year for all the US fossil-fueled generating
 

units large enough to be required to report emissions in the EPA CEM program.
 

•	 Includes CO2, CH4, N20, NOx, SO2 and
 

particulate matter (PM2.5) .
 

•	 Sensitive to regional boundaries which
 

change with power demand and
 

transmission constraints.
 

•	 Typically applied to major power markets
 

(EPA eGRID sub-regions) but can also be
 

analyzed down to the state, sub-state
 

level or utility service area.
 

11 

Major Power Markets (EPA eGRID sub-regions) 
 

 

 

 

Comparison of Emission Rates
 

The chart compares CO2 emission rates using two eGRID methods and the TMM model. 

RSG’s TMM model marginal emission rates are higher than published eGRID rates because 

eGRID emission rates were not designed to be used as marginal emission rates. 

12 
 

 

 

 

 

 

Inp

 

 

 

 

 

MWCOG Avoided Emissions Calculator
 

Dashboard 

Inputs: Outputs: 

Annual Electricity 

Savings: 

Electricity Savings 

Unit: 

1 MWh 1917.11955 Pounds per MWh 

Avoided Emissions 

Rate Unit: 

Pounds 1917.11955 Pounds 

Rate Type: 

Calculations (Rates Taken from "Rate Lookup" Sheet): 

Time Matched Marginal Emissions Rate: Time Matched 

Marginal Rate * (1 kWh/1000 MWh) 

Region: Measure Type: Emissions: Time Matched 

Marginal Rate * 1 Pounds per MWh * (1 kWh/1000 MWh) 

DC Wind 

Pollutant: Time Period: 

Carbon_Dioxide Annual 

Avoided Emissions Rate: 

Avoided Emissions: 

(Choose for Non-Baseload and 

System Average Rates Only) 

(Choose for Time Matched 

Marginal Rate Only) 

Show Calculations 

13 
 

 

 

 

 

 

 

 

 

Lessons Learned from the MWCOG Experience
 

•	 The MWCOG obtained more accurate avoided emission 

measurements compared to previous use of eGRID 

output emission rates. 

•	 Using the TMM model marginal analysis results in 

higher avoided emissions estimates which shows that 

EERE measures can be more cost effective. 

•	 With the use of a model based calculator, routine 

analysis can be completed by agency staff without 

additional runs of the TMM model. 

14 
 

 

 

 

Contact Information
 

For more information: 

http://www.mwcog.org/environment/air/EERE/default.asp 

Jeffrey King 

Principal Environmental Planner
 

Metropolitan Washington Council of 

Governments
 

202-962-3238 direct
 

jking@mwcog.org
 

www.mwcog.org
 

Colin High 

Co-Founder and Principal Consultant 

Resource Systems Group, Inc. 

Office 802.295.4999 x 154 

chigh@rsginc.com 

www.rsginc.com 

15