Researchers at the University of Maryland have developed a solar powered water evaporator that is inexpensively made from wood. The evaporator works through the use of a special technique known as interfacial evaporation. The bottom of the evaporator floats on salt water, while the top absorbs solar heat. As the salt water is pulled up from below, it converts to steam as it reaches the warm surface, leaving the salt behind.
“Wood is an intriguing material scaffold, with its unique hierarchically porous structure, and it is a renewable, abundant and cost-effective resource,” says Liangbing Hu, associate professor of materials science and engineering at the University of Maryland. “In our lab, the fundamental understanding of biomaterials (especially wood) leads us to achieve extraordinary performance that is competitive with widely used but non-sustainable materials.”
From the University of Maryland article: "Hu and his colleagues minimized the need for this maintenance with a device made out of basswood that exploits the wood’s natural structure of the micron-wide channels that carry water and nutrients up the tree.
The researchers supplement these natural channels by drilling a second array of millimeter-wide channels through a thin cross-section of the wood, says Yudi Kuang, a visiting scholar and lead author on the paper. The investigators then briefly expose the top surface to high heat, which carbonizes the surface for greater solar absorption.
In operation, as the device absorbs solar energy, it draws up salty water through the wood’s natural micron-wide channels. Salt is spontaneously exchanged from these tiny channels through natural openings along their sides to the vastly wider drilled channels, and then easily dissolves back into the water below."
Read more about the solar evaporator made of wood at the University of Maryland.