Bolin Chen1 Shan Hu1

1, Iowa State University, Ames, Iowa, United States

New technologies for water desalination and purification is critical to resolve the global water scarcity1,2. Conventional water desalination is large scale and energy intensive. The small-scale point of use water desalination powered by sustainable energy is desired. Solar to thermal energy conversion is the most efficient way to harvest solar energy (more than 90% conversion efficiency)3. Traditional electrical power source can be eliminated by harvesting thermal energy from solar and applied on water desalination. Natural wood as one of abundant substance can be turned into black carbonized woods and worked as solar absorbers by simple carbonization process4. Black carbonized wood can convert solar irradiation to heat. By floating the thin black carbonized wood on the surface of seawater, solar heating is created on the air water interface. seawater is lifted inside the naturally aligned channels by capillary force and evaporated by solar heating. By introducing phase change material (a class of materials that can store a large amount of heat by melting/ freezing) into the black carbonized wood, longer working time and higher evaporation rate is expected. This desalination process required no electricity compared to the traditional method for water desalination like reverse osmosis.

1. Addams L, Boccaletti G, Kerlin M, S. M. Charting our water future: economic frameworks to inform decision-making. McKinsey & Company (2009).
2. Ni, G. et al. Steam generation under one sun enabled by a floating structure with thermal concentration. Nat. Energy 1, 16126 (2016).
3. Yang, J. et al. Hybrid graphene aerogels/phase change material composites: Thermal conductivity, shape-stabilization and light-to-thermal energy storage. Carbon N. Y. 100, 693–702 (2016).
4. Zhu, M. et al. Tree-Inspired Design for High-Efficiency Water Extraction. Adv. Mater. 1704107, 1704107 (2017).