STUDY ON A CARBON EMISSION METHOD FOR SMALL IRRIGATION PUMPING STATIONS BASED ON HYBRID LIFE CYCLE ASSESSMENT THEORY

As an important infrastructure for the irrigation of farmland in plain regions, small irrigation pumping stations are small in scale but large in number. This paper analyzes the full life cycle carbon emission accounting of the irrigation pumping stations from the perspective of ‘dual carbon', which is of great significance for achieving its sustainable development and promoting efficient of water extraction. Based on the carbon footprint theory, this paper adopts a hybrid life cycle assessment method, and divides the whole life cycle of an irrigation pumping station into five stages: material and equipment production, material and equipment transportation, construction, operation and maintenance, and demolition. This study analyzes the carbon emission law of irrigation pumping stations in the whole process of construction, operation, and management, and establishes a carbon emission model accounting method, including the accounting principle, research ideas, calculation process, and the accounting formula, etc. The results show that the total carbon emissions of the six irrigation pumping stations are 402.87, 34.30, 849.37, 140.93, 1645.56, 312.89 t CO₂e, and the annual carbon emission coefficients per unit of irrigated area are 331, 147, 681, 144, 202, 126 kg CO₂e/(hm²·a)), respectively; the carbon emissions of each stage vary greatly, with the largest emissions coming from the operation and maintenance phase(62.57%) and the material and equipment production phase(26.64%), while emissions from the construction phase(5.32%), the dismantling and scrapping phase(4.78%) and the material and equipment transportation phase(0.69%) are relatively smaller. Carbon emissions are influenced by the characteristics of irrigation, pumping station size, irrigation area, irrigated crops, and their water consumption, pumping head, power supply method, etc., and show some variability; the power supply method shows greater variability, with solar PV alone showing lower carbon emissions than uniform grid power supply in comparison, and the former type has the highest emissions during the construction phase(56.67%), followed by the operation and maintenance phase(19.04%). The uncertainty analysis of the parameters shows that the value of the lifetime of the structure is the most sensitive to the carbon emission accounting, and should be considered in the measurement of the actual and comprehensive consideration of the norms to make reasonable values. This has led to targeted carbon reduction measures for different types of irrigation pumping stations at different stages of their carbon emission characteristics. The research results provide a technical reference for scientific accounting of the carbon footprint of irrigation pumping stations, building green and economical water infrastructure, and promoting low-carbon development in rural water resources.