Researchers develop bio-inspired 3D-printed solar steam generators for desalination

With a global freshwater shortage looming, a team in Singapore has been looking at solar steam generators (SSG), which are proving to be a promising device for seawater desalination.

The researchers’ approach uses renewable energy by mimicking the natural water cycle and using solar energy to evaporate and isolate water. Until now, however, this technology has been limited by the need for complicated topologies to increase surface area and thus evaporation efficiency.

To overcome this problem, the researchers were inspired by the structure of trees and harnessed the potential of 3D printing. In the journal Applied Physics Reviews, they present an advanced technology to fabricate efficient SSGs for desalination and introduce a novel method to print functional nanocomposites for multi-jet fusion (MJF).

“We created SSGs with exceptional photothermal performance and self-cleaning properties,” said Kun Zhou, a professor of mechanical engineering at Nanyang Technological University. “Using a treelike porous structure significantly enhances water evaporation rates and ensures continuous operation by preventing salt accumulation—its performance remains relatively stable even after prolonged testing.”

By using a tree-like porous structure, water evaporation rates are significantly increased and continuous operation is ensured by preventing salt deposits. These SSGs absorb solar energy, convert it into heat and evaporate the water. The porous structure contributes to self-cleaning by removing accumulated salt to ensure sustainable desalination performance.

“By using an effective photothermal fusing agent, MJF printing technology can rapidly create parts with intricate designs,” he said. “To improve the photothermal conversion efficiency of fusing agents and printed parts, we developed a novel type of fusing agent derived from metal-organic frameworks.”

The team’s SSGs are inspired by plant transpiration and consist of tiny, tree-shaped microstructures that form an efficient heat-distribution forest.

“Our bio-inspired design increases the surface area of the SSG,” said Zhou. “Using a treelike design increases the surface area of the SSG, which enhances the water transport and boosts evaporation efficiency.” Surprisingly, the SSGs showed a high water evaporation rate in both simulated environments and field tests. The desalinated water always met drinking water standards, even after prolonged testing.

“Our SSGs can be used in regions with limited access to freshwater to provide a sustainable and efficient desalination solution,” said Zhou. “Beyond desalination, it can be adapted for other applications that require efficient solar energy conversion and water purification.”