Calculation of carbon footprints for water diversion and desalination projects

摘要

As greenhouse gas emissions that contribute to global warming increase, it is becoming more important to consider the "carbon footprints" of engineering projects; however, the carbon footprints of water resource projects are often overlooked during environmental impact assessments. Notably, carbon releases occur when water is extracted and transported to industrial, agricultural, and residential areas for use, which consumes energy and materials. For different water extracting and transporting processes, the carbon footprints can be very different. This paper defines the carbon footprint concept in relation to water resources-the carbon emissions generated by acquiring one cubic meter of water-and estimates the carbon footprints for several water resource projects including China's south-to-north water diversion project and desalination plants in the UAE. The results show that the carbon footprint of China's south-to-north water diversion project decreased as the number of operating years increased. When the operation period reaches 30 years, the carbon footprint of China's south-to-north water diversion project will be about 0.179 kg CO2. The carbon footprints for UAE desalination plants were 2.988 kg CO2 for the multi-stage flash (MSF) method, 1.280 kg CO2 for the multiple effect distillation (MED) method, and 2.562 kg CO2 for the reverse osmosis (RO) method. Overall, the results of this study demonstrate that the calculation of carbon footprints for water resource projects can be a valuable source of information for decision-making involving water utilization and conservation.