A solar energy based water purification system is proposed to purify seawater or contaminated water containing heavy metal ions, undesirable chemicals, biological contaminants, suspended solids and gases, etc. The purified water can be used for human consumption (drinking water) and medical, pharmacological, chemical and industrial applications. In this system, solar energy is converted to thermal energy with a solar absorber to purify sea water or contaminated water.
Compared to conventional solar cell with only around 20% efficiency, the solar absorbance of solar absorber is significantly improved with more than 90% efficiency. What’s more, the materials used in the solar absorber are environmentally friendly. Therefore, our solar energy based water purification system is suitable for producing drinkable water. We have developed the key part of the system, i.e., the functional coatings for the solar absorber with excellent performance.
One of the innovative aspects of our water purification system is using solar energy as the energy source. There are two important advantages of our solar absorber based water purification system: 1) high efficiency of solar absorbance, and 2) low thermal emittance after heating to a high temperature. Currently, the full-solar-spectrum absorbing coating on glass achieves a total solar absorbance of ~ 96%, and a total thermal emittance of ~ 4%, 6%, 7%, and 9% at the temperatures of 100, 200, 300, and 400 ℃, respectively. Another advantage of our solar absorber is based on titanium oxide and nitride, which are biocompatible and safe to human. This is very important for producing drinking water.
This technology is designed to produce directly drinkable water from seawater or contaminated water. Without other energy source, the system uses clean and sustainable solar energy to produce clean water. By converting solar energy into thermal energy, solar absorber can also be used to generate electricity by integrating with a conventional power generator. Using solar absorber to produce drinkable water is a new approach.
Water crisis is a world issue. A huge amount of money has been invested in the area of water purification. Especially, in Singapore, water resource is very limited. Singapore government has planned to produce 30% of clean water by using desalination technology by 2060. It is feasible to use solar energy to drive our solar absorber based water purification system to desalinate seawater. Unlike reverse osmosis technology, which consumes a large amount of electrical energy, our solar absorber based water purification system mainly depends on the solar energy.