In a new bit of biomimicry (those instances where sciences takes its cue from the structure of systems in the natural world), researchers at Cornell have developed a synthetic system for transpiration.
Scientists theorize that as evaporation occurs on the surface of a tree’s leaves, the resulting drop in water pressure propels water from the earth and through their bodies. The same principle pulls oil through the wick of a candle.
Cornell University researchers modeled the water-transporting tissue, called “xylem,” with fine networks of hydrogel-embedded capillaries. The hydrogel itself had nanometer-scale pores — the same material is used in contact lenses — that allowed water to evaporate, creating the necessary pressure differential.
The artificial tree proved capable of transporting water, raising the possibility of applying transpiration mechanisms to the heating systems of buildings or the cooling systems of computers. [via] [paper published in nature]
The Cornell experiment, however, is not the first time that such reverse engineering of nature has been put to good effect. In 2004, Project TERMES ventured off to Namibia in Southern Africa to map out the structure of the Macrotermes michaelseni termite’s mound. From the press release announcing the expedition, the team stated:
The termite-built towers, standing as high as five metres, epitomise structures that have been optimised for the harsh surroundings they are located in, displaying incredible feats of self-regulation to provide a constant living environment in which the termites can thrive. These wind driven machines, that ventilate the termites’ colony, breathe at about the same rate as a cow and need to be large to continually refresh the air to the subterranean nests.
Understanding how the minuscule termites build these complex mounds may enable engineers and architects to develop new kinds of self-sufficient human habitats, which are able to tap environmental energy like wind and solar power to control their own climate. The biologists also hope that clues to fundamental questions about the evolution of organisms will emerge from this work.
After filling the mound with a type of plaster and then dissolving the exterior walls, the researchers were able to create a 3D model of the internal structure. It is rather amazing that the collective action of these termites has evolved in such a way as to generate this amazingly balanced and harmonious artifact, while our own civilization seems to extrude quite a different, self destructive set of artifacts. Curious.
Left: The Eastgate building in Zimbabwe constructed on principals developed from studies of termite mounds. Right: Macrotermes michaelseni termite mound
To much fanfare a few years ago, the Eastgate building was built in Zimbabwe using techniques learned from the study of the termite mounds, yielding 90% higher energy efficiency than buildings of similar size:
This is a terrific example of sustainable architecture that is biomimetic, indigenous, and economically viable on its face. Yet the Eastgate story also demonstrates an important aspect of the sustainability/biomimicry trend - that incrementally greater value may be found by studying solutions from those niches (ecological and economic) where resources are more constrained than the ones you inhabit. Don’t study the oasis - study the desert. More on the Eastgate building is available here and here.