Water resources are a fundamental material basis for the survival and development of human society. As the global population continues to grow and lifestyles change, the scarcity of freshwater has become a growing concern worldwide. China, with 20% of the world’s population, possesses only 6% of the world's total water resources, and per capita availability is just one-fourth of the global average. This severe shortage has significantly hindered economic growth and disrupted ecological balance. To address this issue, seawater desalination has emerged as a promising solution. However, China still lags behind many foreign countries in terms of technology and industrial scale.
**Technology Gap with Foreign Countries**
1. **Research and Development**: Core components such as low-temperature multi-effect systems, reverse osmosis membranes, high-pressure pumps, and energy recovery devices are largely imported. Domestic R&D lacks depth, and there is a lack of large-scale engineering practices for desalination equipment. The concept of nuclear-powered desalination is still in early stages, with no real-world applications yet.
2. **Industrial Scale**: Most Chinese desalination projects operate on a 1,000-ton scale, while international projects often reach 100,000 tons. China’s share of global desalination production is less than 0.3%, highlighting a significant gap.
3. **Implementation Mechanism**: There is no centralized agency or industry alliance to coordinate efforts. A coordinated approach involving government policy, technological innovation, and industry collaboration is essential for sustainable development.
4. **Demonstration and Investment**: Insufficient state investment in large-scale demonstration projects limits the application and commercialization of new technologies.
**Solar Desalination Technology Status**
The cost of desalination remains a major challenge. For a 10,000-ton/day reverse osmosis plant, the total cost per ton of water is approximately 4.2–5.4 yuan, with power and depreciation being the largest expenses. To reduce costs and meet specific needs, solar desalination has been developed.
Solar desalination can be divided into two main types: direct and indirect methods.
**Direct Method**
This method uses solar collectors to heat seawater directly, causing evaporation and condensation into fresh water. It includes shallow disk, tilted, and multi-effect distillation devices. Shallow disk systems are simple but produce low output, while tilted and multi-effect systems offer higher efficiency but face technical challenges.
**Indirect Method**
This method uses solar energy to generate either heat or electricity, which is then used to drive desalination processes. Distillation, reverse osmosis, and electrodialysis are common approaches. While more efficient, these systems are complex and costly.
**Adsorption Solar Desalination System**
A promising new technology is the adsorption-based solar desalination system. It uses materials like zeolite and activated carbon to adsorb water vapor, which is then released under solar heating. This system offers high efficiency, low operating costs, and environmental benefits. However, key challenges remain, including improving thermal conductivity, optimizing heat transfer, and enhancing system coordination.
In conclusion, while solar desalination holds great potential, further research and development are needed to make it commercially viable. With continued innovation and investment, this technology could play a crucial role in addressing global water shortages, especially in remote areas and islands.
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Hebei Qianmu Fastener Manufacturing Co., Ltd , https://www.qmjgjfasteners.com