Harvesting Water through Biomimicry
Scientists are working hard to address the interrelated challenges of climate change and water scarcity – climate change worsens water scarcity, and in turn water shortages inhibit hydro power generation, leading to more greenhouse gases being emitted from dirtier methods of electricity generation. Nasty positive feedback loop, yes.
Fortunately, emulating the genius of nature is helping scientists harvest water from the air. Harvard scientists have created a hybrid material inspired by the unique shell of the Namib desert beetle, the V-shaped spines of cacti, and the slippery coating of carnivorous pitcher plants.
The mechanism is called dropwise condensation, which refers to “collecting water on a surface as quickly as possible while also moving that collected water away.”
According to the research article, published in Nature:
“Controlling dropwise condensation is fundamental to water harvesting systems, desalination, thermal power generation, air conditioning, distillation towers, and numerous other applications. For any of these, it is essential to design surfaces that enable droplets to grow rapidly and to be shed as quickly as possible. However, approaches based on microscale, nanoscale or molecular-scale textures suffer from intrinsic tradeoffs that make it difficult to optimize both growth and transport at once.”
To overcome this challenge, the scientists designed a material that learns from the properties of the Namib desert beetle’s shell to promote condensation into droplets, the cacti structure to channel the water away, and the smoothness of the slippery coating of pitcher plants to accelerate the movement of the droplets.
The scientists conclude:
“We further observe an unprecedented sixfold-higher exponent of growth rate, faster onset, higher steady-state turnover rate, and a greater volume of water collected compared to other surfaces. We envision that this fundamental understanding and rational design strategy can be applied to a wide range of water-harvesting and phase-change heat-transfer applications.”
This example of leveraging nature’s wisdom is a hopeful one as we face unprecedented challenges from climate change and water scarcity.