Catalyzing System-level Decarbonization: An Analysis of Carbon Matching As An Accounting Framework

TL;DR

The paper confronts shortcomings of the Greenhouse Gas Protocol's Scope 2 accounting by introducing carbon matching, a framework that assigns emissions to grid elements using Marginal Emissions Rates ($MER$) rather than uniform averages. It provides precise mathematical definitions for GHGP and MER-based footprints, demonstrates the approach on a simple 3-bus grid, and extends to a realistic ERCOT-like grid, showing that MER-based footprints balance total emissions and are more responsive to grid constraints. The authors prove system balance under MER accounting (both when MER is constant and when it varies by bus) and argue that MERs naturally reflect transmission constraints and deliverability, while also incentivizing infrastructure investments in transmission and storage. Through realistic simulations and open-source tools, the work positions carbon matching as a rigorous, actionable method for advancing system-wide decarbonization. The framework thus offers a consequential, location- and time-sensitive alternative to conventional GHGP methods with implications for policy, corporate reporting, and grid investment decisions.

Abstract

Carbon matching aims to improve corporate carbon accounting by tracking emissions rather than energy consumption and production. We present a mathematical derivation of carbon matching using marginal emission rates, where the unit of matching is tons of carbon emitted. We present analysis and open source notebooks showing how marginal emissions can be calculated on simulated electric bus networks. Importantly, we prove mathematically that distinct emissions rates can be assigned to all aspects of the electric grid - including transmission, storage, generation, and consumption - completely allocating electric grid emissions. We show that carbon matching is an accurate carbon accounting framework that can inspire ambitious and impactful action. This research fills a gap by blending carbon accounting expertise and power systems modeling to consider the effectiveness of alternative methodologies for allocating electric system emissions.

Figures (6)

• Figure 1: Base state of hypothetical three bus, transmission constrained network. Red buses are generators and blue buses are loads. Abbreviations are described in Table \ref{['table:variables']}
• Figure 2: Snapshot of cost optimized three bus transmission constrained example. Note that the Scope 1 emission (27 tons/h) is equal to the combined footprint of loads (81 ton/h) plus the generation footprint (0 ton/h) and transmission (-54 ton/h).
• Figure 3: Hypothetical network under proposed expansion
• Figure 4: Simple grid example for exploring frameworks response to a new load at bus 4. Red buses are generators and blue buses are loads. Abbreviations are described in Table \ref{['table:variables']}
• Figure 5: Simplified 75 bus simulation of a single time step of the ERCOT grid. [Left] Generator contribution and relative line loading [Right] Marginal Emissions Rates at buses and lines