Carbon emissions refer to the amount of carbon dioxide emissions produced per unit area or unit energy per unit time, and are an important indicator for measuring the impact of human activities on global climate change. There are various methods for calculating carbon emissions, mainly including direct calculation and indirect calculation. This article shares and introduces these two types of calculation methods, and explains them with specific examples.

1. Direct calculation method

The direct calculation method is to determine carbon emissions by measuring or estimating energy use and carbon dioxide content. The specific method is as follows:

1. Calculation of carbon emissions from electricity and thermal energy

The carbon emissions from electricity and heat can be calculated by measuring the energy input and carbon content of the energy.

The formula is: E=P × C

Among them, E represents carbon dioxide emissions, P represents energy consumption (such as electricity or heat), and C represents the carbon content per unit of energy.

2. Calculation of carbon emissions from fuel combustion

The carbon emissions from fuel combustion can be calculated by measuring the consumption and carbon content of the fuel.

The formula is: E=V × C × G

Among them, E represents carbon dioxide emissions, V represents fuel consumption (such as coal, oil, natural gas, etc.), C represents the carbon content per unit of fuel, and G represents the carbon oxidation rate of the fuel (generally assumed to be 100%).

Example: Calculation of carbon emissions from coal consumption in factories

Assuming a factory uses 1000 tons of coal as energy within a year, the average emission factor of coal is 2.471 tons of CO2/ton.

So, the direct carbon emissions of this factory are:

1000 tons x 2.471 tons CO2/ton x 100%=2471 tons CO2

2. Indirect calculation method

The indirect calculation method is to indirectly estimate carbon emissions by analyzing the influencing factors of economic activities. The specific methods include production method, consumption method, and industry chain method.

1. Production method

The production method calculates carbon emissions by estimating the carbon content of energy and raw materials consumed during the production process of a product, as well as the corresponding product output.

The formula is: E=P × C

Among them, E represents the carbon dioxide emissions, P represents the product output, and C represents the carbon content per unit of product.

2. Consumer Law

The consumption law estimates energy consumption and carbon dioxide emissions by investigating and statistically analyzing consumers' energy consumption behavior. For example, estimating carbon emissions by investigating household electricity consumption.

3. Industry Chain Law

The industry chain method analyzes the supply chain and value chain, calculates the energy consumption and carbon dioxide emissions of each link in the entire industry chain, and estimates the overall carbon emissions. This method is suitable for estimating carbon emissions in complex economic activities.

Example: Calculation of carbon emissions from electricity consumption in shopping malls

Assuming a shopping mall uses 1000 kilowatt hours (kWh) of electricity within a year, and the marginal emission rate of the area is 0.000709 tons of CO2/kWh.

So, the indirect carbon emissions of the mall are:

1000kWh × 0.000709 tons CO2/kWh=0.709 tons CO2

3. Accounting method for carbon emissions

At present, there are three main methods for calculating carbon emissions: emission factor method, mass balance method, and actual measurement method.

1. Emission factor method

The emission factor method is the most commonly used approach to calculate carbon emissions based on activity data and emission factors.

The formula is: greenhouse gas (GHG) emissions=activity data (AD) x emission factor (EF)

2. Quality balance method

The mass balance method determines carbon emissions by calculating the difference between the input carbon content and the output carbon content.

The formula is: Carbon dioxide (CO2) emissions=(raw material input x raw material carbon content - product output x product carbon content - waste output x waste carbon content) x 44/12

3. Actual measurement method

The actual measurement method is based on the measured basic data of emission sources, and summarizes the relevant carbon emissions. Both on-site and off-site measurements are included, with on-site measurements typically having higher accuracy.

4. Precautions

When calculating carbon emissions, the following points should be noted:

1. Data accuracy: Ensure the accuracy of key parameters such as activity data and emission factors to avoid calculation bias.

2. Reliability of data sources: Data should come from reliable channels, such as statistical data, survey data, or standard values published by international organizations.

3. Industry differences: Different industries and regions may have different calculation methods and standards, which need to be adjusted according to actual situations.

4. Regular updates: With changes in energy structure and technology, parameters such as carbon emission factors need to be updated regularly to maintain the accuracy of calculation results.