Investigation of Carbon Emission Flow Modeling Methods for Integrated Electricity and Heat System

In the context of global carbon peaking and carbon neutrality, the low-carbon development of integrated energy systems is critically important. Carbon emission flow (CEF) model can track and identify the flow paths and transformation processes of carbon emissions within energy systems, serving as an efficient tool for carbon evaluation. However, the application of CEF modeling methods in integrated electricity and heat systems remains underdeveloped, particularly lacking computational paradigms for district heating networks with multiple loops and multiple heat sources. This study investigates energy flow based CEF modeling theory and conducts a case analysis, focusing on an integrated energy system composed of a 6-node power network and an 8-node district heating network coupled together. Based on the CEF calculation results, the node with the highest carbon emissions in power system is Load 2 (79.9 tCO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>/h), while the node with the lowest carbon emission intensity is Load 3 (0.447 tCO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>/MWh). In the heating system, carbon emissions due to network losses account for 19.3% of the total emissions. There are five different carbon emission intensities across all nodes, and carbon emission intensities of supply and return water nodes are not necessarily equal. The node with the highest carbon emissions is Load 1 (7.87 tCO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>/h), while the node with the lowest carbon emission intensity is Load 3 (0.358 tCO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>/MWh). Based on the CEF model, guiding recommendations can be provided for low-carbon transformation and allocation of carbon emission responsibilities within the energy system.