There are three common ways to get fresh water in the world: underground water intake, long-distance water transfer and seawater desalination. Groundwater exploitation, as an important open source measure, has the attractive advantages of small engineering quantity and low cost. However, the amount of underground water intake is greatly limited by resource conditions, and in many areas, due to over-exploitation of groundwater, underground funnels are formed, which leads to the inclination of houses and even environmental hazards such as seawater intrusion, and the exploitation of groundwater is restricted.
Long-distance water transfer does not include the investment cost of the project and the indirect economic loss of the water transfer area, but only includes the daily operation cost and management fee, which is quite different from the real cost. In fact, besides huge investment, the water transfer project also occupies a lot of cultivated land, and there are also problems such as environmental harm in the water transfer area. For example, the Yellow River Diversion Project to Qingdao (Island) covers an area of 62,000 mu, which will also cause ecological and environmental problems such as the interruption of the Yellow River and the destruction of vegetation, which is incalculable economically. The Luanhe River Diversion Project implemented in 1980s still needs about 2.3 yuan per cubic meter today, which is 1.4 yuan according to the water price of Tianjin residents, and the government subsidy starts from 0.9 yuan. Experts predict that after the implementation of the South-to-North Water Transfer Project, the Yangtze River will flow to Beijing, and the comprehensive cost will be above 5 yuan/cubic meter at present. Some experts even predict that every cubic meter will reach 20 yuan. According to American data, the cost of long-distance water transfer over 40 kilometers will exceed that of seawater desalination.
For seawater desalination, energy consumption is the key to directly determine its cost. In the past 40 years, with the progress of technology, the energy consumption index of seawater desalination has been reduced by about 90% (from 26.4kwh/m3 to 2.9kwh/m3), and the cost has been greatly reduced. At present, the cost of seawater desalination in China has dropped to 4-7 yuan /m3, and the cost of brackish water desalination has dropped to 2-4 yuan /m3. For example, the cost of seawater desalination in Tianjin Dagang Power Plant is about 5 yuan /m3, and that of brackish water desalination in Cangzhou City, Hebei Province is about 2.5 yuan /m3. If the desalted concentrated brine is further comprehensively utilized to make salt and extract chemicals, the desalting cost can be greatly reduced. As for some productive process water, such as power plant boiler water, it needs to be reprocessed with tap water because of its high water quality requirements, and its comprehensive cost will be much higher than the one-time treatment cost of seawater desalination. It can be seen that the unit cost of seawater desalination, especially brackish water desalination, is actually very competitive if the policy factors such as government subsidies are put aside and analyzed from the economic and technical levels alone.
Cost comparison unit of several fresh water acquisition methods: yuan/cubic meter
Average cost of water intake mode
The exploitation of groundwater limits the amount of exploitation.
Diversion from Luanhe River to Tianjin: 2.3 yuan/m3 (direct cost)
South-to-North Water Transfer Project: 5-20 yuan/m3 (average water price in Beijing)
Seawater desalination: 4-7 yuan /m3 (comprehensive cost)
Bitter salt water: 2-4 yuan /m3 (comprehensive cost)
In China, due to the influence of planned economy, a benign water price formation mechanism has not been formed for a long time, and the price of tap water seriously deviates from its value. The government bears huge subsidies, and the price of tap water is generally low. The price of tap water is generally 1.5-2 yuan /m3. With the continuous progress of seawater desalination technology and the emergence of industrial scale benefits, the cost of seawater desalination (brackish water) will be lower and lower. On June 5438+ 10, 2000, Premier Zhu Rongji emphasized at the South-to-North Water Transfer Symposium that it is necessary to establish a reasonable water price formation mechanism, gradually raise water prices by a large margin, and give full play to the role of price leverage. With the increasing shortage of fresh water resources, cities have introduced water-saving measures to limit the use of tap water and increase prices excessively. It can be predicted that in the near future, on the one hand, the cost of seawater desalination is decreasing, on the other hand, the price of tap water is rising, and the two will get closer and closer. The price of tap water will even be higher than the cost of desalination of brackish water, so the cost problem of desalination will be solved. The solution of the cost problem will greatly promote the wide application and industrialization of seawater desalination.
In view of the above situation, we have invested a lot of money, manpower and material resources in in-depth research, analysis and comparison of international seawater desalination equipment and technology, and conducted relevant research according to domestic market demand and economic affordability. In view of the specific situation of China's coastal areas, islands, ocean-going transport ships and a large number of fishing boats, after years of research and development, we have finally successfully designed and produced seawater desalination equipment (patented products) with independent knowledge, and the technical indicators are higher than those of foreign countries. The process has been optimized and a lot of manpower and material resources have been condensed. After a lot of data collection, prototype design, raw material selection, and testing and comparison of various materials, the field test was carried out at sea. The problems found in the improvement are not perfect in technology, and they are integrated into a relatively perfect technological process to reduce operating costs. The cost of the whole machine is much lower than that of foreign models. The cost per ton of domestic water has exceeded the 3 yuan mark, which is equivalent to the price of tap water. The production cost of raw and drinking fresh water is also collected in 4.8 yuan, and the product cost is lower than the index of similar enterprises. Because the system does not use the dosing link, the discharged pus has no pollution to the environment. Our company has made specific requirements in the Catalogue of National Major Environmental Protection Technology and Equipment (20 1 1). Considering our requirements, the process has reached or exceeded all the indexes in the technical requirements, and it is in the forefront of seawater desalination peers. It can be mass-produced and put on the market anytime and anywhere. The operation of the whole machine is simplified, the appearance is miniaturized, the process is rationalized, and the water quality is excellent.