Desalination and South-to-North Water Transfer are both ways to solve the problem of water scarcity, but why is South-to-North Water Diversion currently preferred to desalination?This is a question of energy consumption, infrastructure investment, water efficiency, and environmental impact.
First of all, seawater desalination requires a lot of energy to desalinate the treatment, and the best efficiency at present is about 3 kWh of electricity. In general, desalination is often combined with the use of waste heat from large thermal power plants for desalination, which can reduce energy consumption. However, despite the continuous advancement of desalination technology, it still requires a large amount of energy input, which limits the large-scale application of desalination to a certain extent.
In contrast, South-to-North Water Transfer is an investment in infrastructure in exchange for water resources. The main investment is in the construction of water channels, and even if the eastern route uses pumping stations to lift water, it consumes much less electricity than desalination. For example, 3 kWh of electricity can pump water up to 800 meters, while the total head of the eastern route is only 45 meters, so the South-to-North Water Diversion Project has certain advantages in energy consumption.
In addition, the water treated by desalination can be used directly as tap water, but it is suitable for short distance transportation. The South-to-North Water Diversion Project transports water resources through channels, which can be transported to places where they are needed over long distances, so it has certain advantages in the efficiency of water resource transmission.
In addition, the discharge of concentrated brine from desalination into the ocean poses a threat to marine ecology, especially in areas where water exchange is slow, such as the Bohai Sea. The use of desalination for water resources in individual cities may not be too much of a problem, but if they rely on desalination in their entirety, it may have an impact on marine ecology.
In summary, seawater desalination and south-to-north water diversion have their own advantages and limitations. Seawater desalination consumes a large amount of energy, is suitable for short-distance transportation, and has a certain impact on marine ecologyThe South-to-North Water Diversion Project, on the other hand, uses infrastructure investment in exchange for water resources, which has low energy consumption and is suitable for long-distance transportation, but requires a large amount of infrastructure investment. Therefore, it is necessary to comprehensively consider various factors and choose the appropriate water resource allocation method in practical application to achieve the dual goals of rational use of water resources and environmental protection.