OpenEAC Alliance

Decarbonization Accounting

ApprovedPublished 2025-02-07

Foreword

This document has been prepared by the OpenEAC Alliance, a collaborative group of energy engineering and measurement and verification professionals focused on creating transparent and standardized methods to measure the environmental impacts of demand side interventions. These methodologies are designed to align with best practices and reflect input from industry experts. The OpenEAC Alliance aims to enhance accountability and consistency in documenting energy and carbon savings from distributed energy resources (DERs).

About the OpenEAC Alliance

The OpenEAC Alliance is an organization of professionals dedicated to standardizing the measurement and verification of DERs. By focusing on clarity and rigor, the Alliance aims to overcome challenges that have hindered the proper valuation of DERs for their climate benefits. Central to this effort is the Energy Attribute Certificate (EAC), a standard that provides a detailed, auditable record of energy project impacts, including attributes such as type, timing, and location of energy production or reduction.

The OpenEAC Alliance collaborates to develop open-source methodologies, ensuring that DER projects can be accurately measured, verified, and valued in a way that promotes trust and drives market adoption.

Introduction

This document introduces a standardized approach for measuring the carbon impacts of an Asset based on the energy impacts of that Asset.

An Asset receives electricity from the grid to which it is interconnected. The source of this electricity comes from a variety of power plants that are dispatched according to contracts and bidding mechanisms established by the balancing authority. The Asset operator can choose to consume or not consume electricity during a particular period of time, but does not have control over the source of electricity provided by the grid operator.

Normative References

  • US Balancing Authority Consumed Average Grid Carbon Intensity Data: hourly CO₂ emissions and electricity interchange for every US balancing authority, published by the US Energy Information Administration in the Hourly Electric Grid Monitor. Data and its documentation: https://www.eia.gov/electricity/gridmonitor/about.

    • The method that converts produced emissions into consumed emissions, by tracing hourly power flows between interchanging balancing authorities, is given in: de Chalendar, J. A., Taggart, J., and Benson, S. M., “Tracking emissions in the US electricity system”, Proceedings of the National Academy of Sciences, vol. 116, no. 51, pp. 25497–25502, 2019. DOI: 10.1073/pnas.1912950116. https://doi.org/10.1073/pnas.1912950116.

  • Marginal Grid Carbon Intensity Data: any of the following published sources may be used. Each publishes at hourly or finer resolution, so each can be matched to the hour of consumption.

  • Avoided Fuel CO2e Emissions Factors

Terms and Definitions

  • Produced electricity mix: The aggregate amount of electricity dispatched onto a grid from power plants within a particular balancing authority. This number does not include imports or exports to/from neighboring balancing authorities.

  • Consumed electricity mix: The aggregate amount of electricity consumed within a grid including power dispatched from power plants within the grid and any imported power from neighboring grids and deducting any power exported to neighboring grids.

  • Average Carbon Intensity: Measured as a CO2e weight per unit of electricity produced (e.g., lbs/mwh or grams/kwh). Calculated by multiplying the Emissions Factor for each fuel type in the electricity mix by the total amount of each fuel in the Generation Mix and weighting the average by the percentage of each fuel type in the overall mix.

  • Marginal Carbon Intensity: The change in total CO₂e emissions on a grid per unit change in electricity demand at a given hour and location, expressed as a CO₂e weight per unit of electricity (e.g., lbs/MWh or grams/kWh). Unlike Carbon Intensity, it is not an average over the electricity mix, and it can be higher or lower than that average in the same hour.

Scope

When calculating emissions for an Asset, it is best practice to use the carbon intensity emissions factor that is computed using the consumed electricity mix on at least an hourly interval.

Methodology

1 Match Asset to Carbon Data Aggregation: Depending on the source of data, the carbon intensity data will represent different grid geographies.

1.1 Grid Geographies:

1.1.1 Balancing-Authority-Level (EIA):

1.1.1.1 Using the Asset’s latitude and longitude and this Balancing Authority Geojson/Map (originally created and made public by HIFLD)

1.2 If there are more than one grid operators that match a location, a manual review should be conducted to determine the correct assignment for the Asset.

2 Calculate Decarbonization Impact: The decarbonization impact for a given hour is the avoided emissions minus the generated emissions for that hour.

2.1 Local Fuel Emissions Impact: For the avoided fuel calculation, use the CO2e emissions factors that are derived from Table 7.1.2(1) National Average Emissions Factors for Household Fuels from draft ANSI/RESNET/ICCC 301 Standard for the Calculation and Labeling of the Energy Performance of Dwelling and Sleeping Units using an Energy Rating Index. These factors include both the combustion and pre-combustion (e.g., methane leakage for natural gas) CO2e emissions.

2.1.1 Natural Gas: ~0.228 kg/kWh

2.1.2 Fuel Oil: ~0.303 kg/kWh

2.2 Grid Average Emissions Impact: Match the additional electricity consumption to the consumed carbon intensity of the grid at that hour.

2.2.1 If an hour is missing a grid emissions factor, the corresponding carbon intensity value for that hour should be filled in with non-missing values for the preceding and subsequent intervals with a limit of +/- 3hours, and if still null, with the preceding or subsequent day.

2.3 Grid Marginal Emissions Impact: Match the additional electricity consumption to the marginal carbon intensity of the grid at that hour.