Carbon Emission Flow Theory and Application

Carbon emission flow theory & application

The carbon emission from the Electric Power industry takes about 40% of the total carbon emission in the world, which makes the low carbon transformation of the power system attract great attention. Electricity is typical secondary energy. The carbon emission of power systems almost entirely comes from power generation. However, the main responsibility for carbon emissions in power systems is taken by the demand side, as the generation has to real-time follow the consumption in the power system. Therefore, an accurate and reasonable method for carbon emission measuring for the demand side is needed. In this regard, we proposed a power system carbon emission flow theory for real-time and precisely measuring the carbon emission of using electricity. After that, the application field of carbon emission flow theory is extended to multiple energy systems. To achieve automatically measure carbon emission information, we have developed a carbon metering system based on the proposed theory. We have also proposed a new power system carbon emission reduction mechanism named low-carbon demand response.

Carbon Emission Flow in Power System

To address the challenge of accurately measuring and tracking carbon emissions throughout the entire electrical power system, we have undertaken research and proposed a method for analyzing the flow of carbon emissions within the system. This method establishes the fundamental theoretical framework for understanding the flow of carbon emissions. The flow of carbon emissions within the electrical power system is defined as a virtual network flow that is attached to the power flow and used to represent the carbon emissions that sustain the flow in any branch of the system. Essentially, this flow of carbon emissions can be viewed as adding a label for carbon emissions to each flow on each branch of the electrical power system. Given the relationship between the flow of carbon emissions and the power flow, it can be assumed that the flow of carbon emissions in the electrical power system begins at the source node, enters the system as the power plant connects to the grid, follows the power flow within the grid, and finally reaches the load node.

Carbon Emission Flow in Multiple Energy System (MES)

Compared to a single energy system, MES exhibits more intricate carbon emission characteristics, characterized by numerous interrelated carbon emission segments and the inter-system transfer of carbon emissions. These attributes present substantial difficulties in the analysis of carbon emissions from multi-energy systems. Our examination and modeling of the complex carbon emission features of MES have led to the establishment of a carbon emission flow theory for MES, with carbon serving as a linking factor for coordination and optimization among different systems. This has facilitated the creation of a low-carbon analysis and optimization methodology, enabling a more precise identification of system emissions, enhancing the level of low-carbon decision-making, and supporting the transformation of actual energy systems.

Carbon Metering System

To improve the precision and efficiency of carbon emission measurement and tracking in the power system, we have developed a carbon metering system. The system provides real-time measurement and recording of the key indicators of carbon emissions within the power system, in compliance with the IPCC's principles of measurability, reportability, and verifiability. The carbon metering system consists of carbon meters situated at various points in the network where carbon emissions need to be recorded, a central server, and communication links connecting the carbon meters and the central server. The central server operates as the computing center, responsible for computing carbon emission flow and exchanging data with the carbon meters through communication. The carbon meters can be classified into several categories based on their placement:
1. Generation Carbon Meter: A device for real-time measurement of carbon emissions generated during power generation.
2. Network Carbon Meter: A device that measures carbon emissions at the terminal nodes of regional interconnection lines.
3. Distribution Carbon Meter: A device that measures the average and marginal local carbon intensities of distribution feeders.
4. Consumption Carbon Meter: A device that provides instantaneous and accumulated information about carbon emissions corresponding to a consumer's energy consumption.

Low Carbon Demand Response

Based on the theory of carbon emissions flow in the power system, a new power system carbon emission reduction mechanism that guides users to actively respond and reduce the power system carbon emissions, namely a low-carbon demand response mechanism. The dynamic carbon emission factors, which can real-time reflect the differences in carbon emission per MWh in different time periods, are taken as the guiding signal. The willingness to carbon emission reduction or the price in the carbon market is taken as the incentive signal. After perceiving the dynamic carbon emission factors, users can reduce their electric consumption carbon emission by shifting the load from periods of high carbon emission factors to periods of low carbon emission factors. The carbon emission reduction from low-carbon demand response can be estimated by comparing the actual carbon emission with the carbon emission from the baseline load curve.

Low Carbon Demand Response

1. Wujing Huang, Ning Zhang*, Yaohua Cheng, Jingwei Yang, Yi Wang, Chongqing Kang. Multienergy Networks Analytics: Standardized Modeling, Optimization and Low Carbon Analysis. Proceedings of IEEE. 2020, 108(9): 1411 - 1436.

2. Yaohua Cheng, Ning Zhang, Daniel S. Kirschen, Wujing Huang, Chongqing Kang. Planning multiple energy systems for low-carbon districts with high penetration of renewable energy: An empirical study in China. Applied Energy, 2020, 261: 114390.

3. Yaohua. Cheng, Ning Zhang, Baosen Zhang, Chongqing Kang, Weimin Xi and Mengshuang Feng, Low-Carbon Operation of Multiple Energy Systems Based on Energy-Carbon Integrated Prices, IEEE Transactions on Smart Grid. 2020,11(2): 1061-1074.

4. Yaohua Cheng, Ning Zhang, Zongxiang Lu and Chongqing Kang. Planning multiple energy systems toward low-carbon society: a decentralized approach, IEEE Transactions on Smart Grid, 2019 10(5): 4859-4869.

5. Yaohua Cheng, Ning Zhang, Yi Wang, Jingwei Yang, Chongqing Kang* and Qing Xia. Modeling carbon emission flow in multiple energy systems, IEEE Transactions on Smart Grid, 2019, 10(4):3562-3574.

6. Yanlong Sun, Chongqing Kang, Qing Xia, Qixin Chen, Ning Zhang* and Yaohua Cheng. Analysis of transmission expansion planning considering consumption-based carbon emission accounting, Applied Energy, 2017, 193: 232-242.