Embodied carbon budget accounting system for calculating carbon footprint of large hydropower project

Large hydropower project (LHP) is now the most important renewable and low-carbon source for electricity generation, carbon footprint calculation is crucial for it. We established an embodied carbon budget accounting system for LHP to calculate its actual carbon footprint. In additional to traditional carbon emission from plant construction, the accounting system included two new items in the carbon footprint of a hydropower project: carbon reductions due to the provision of extra services, and carbon emissions due to the decrease in adjacent ecosystem services. We classified these three items into main products and by-products for LHP in its lifecycle, formed a carbon footprint inventory, then quantified the direct and indirect emissions and reductions embodied in these products. This approach leads to a relatively complete carbon footprint assessment. According to this approach, embodied carbon emissions and reductions for the Zhikong hydropower project (Tibet, China) were 3.98 × 1012 and 6.89 × 109 g CO2 equivalents (CO2-e), respectively. Therefore, the total carbon footprint is 3.97 × 1012 g CO2-e, equivalent to a carbon emission intensity of 195 g CO2-e kWh−1. This is 111.17% higher than the traditional carbon footprint for this project. The results indicate that the low-carbon status of LHP may be overestimated at present, and could help in preventing the blind enthusiasm on LHP in low-carbon energy choice.