Research on greenhouse gas emissions accounting methods in environmental impact assessment of construction projects: a case of thermal power project

The current greenhouse gas (GHG) emissions accounting method standards and guidelines were systematically sorted out, the differences of the current accounting methods were analyzed, the problems of the current accounting methods being incorporated into the environmental impact assessment (EIA) system were put forward, and the thermal power industry was taken as an example to put forward the carbon emission accounting boundary, calculation method and principles for selecting parameters in the EIA of thermal power construction projects. The results showed that the current GHG emissions accounting methods had certain discrepancies in accounting boundaries, scopes, factors and calculation methods. The current accounting methods could not be directly applied to the EIA of construction projects, and there were problems such as the inability to obtain the parameters accounting accurately, the inconformity of calculation boundaries with the requirements of EIA, and the difference in the recommended parameters among various guidelines. For the thermal power industry, from the perspective of the carbon emission sources considered, the fossil fuel combustion emissions accounted for 93.5%-99.8%. When carrying out the EIA, the fuel combustion emissions of generator sets could be mainly considered and other process emissions could be excluded. In terms of calculation methods, the calculation results of carbon dioxide based on elemental carbon content were relatively accurate, with an calculation error not exceeding 10%, while the error based on low-level calorific value was 18%-30%. It was recommended to carry out accounting based on elemental carbon content when conducting EIA. It was suggested to select the estimated value at the EIA stage for the fuel consumption of the coal-fired power plant, and select the measured value of the designed coal samples at the EIA stage for the elemental carbon content, avoiding using the default value of low-level calorific value and carbon content per unit calorific value. Also, it was recommended to directly select the default value for the carbon oxidation rate.