Waste Sponge as Solar Absorber for Vapour Generation

Around 70% of our world is covered in water, but only 2.5% of the earth’s water is fresh. As most freshwater is trapped in glaciers and snowfields, easily accessible freshwater represents only 1% of our earth’s total water volume. Utilizing solar energy to extract freshwater is a green and promising strategy in addressing this issue. PolyU has designed a convenient solar steam generation device by using specially treated recycled black sponge as solar absorber. It can float on the air-water surface while converting solar energy into heat to evaporate the top layer of liquid. Then the generated vapour will condense on the cold inner cover of the device and become freshwater droplets, which can be collected as distilled water continuously under the sun. The concept can also be adopted for solar waste water treatment, solar alcohol concentration or solar distillation of other materials.