Monday, February 15, 2016

Cloaking buildings



Every once in a while I find a reason to be optimistic.

I saw this article on PBS' NOVA site that describes a new method of architecture that could protect buildings from earthquake and tsunami waves by "cloaking." Of course people have been trying to adapt architecture to factors of our environment since time immemorial. The article mentions Pliny the Elder and his description of Greek temples. A layer of sheepskin would be placed across the temple's foundation, allowing for the ground to move and sway without bringing damage to the building above it. Our current mechanical systems operate much the same way, giving a building the ability to move or absorb the shockwaves through springs (see Cheyenne Mountain/NORAD). There may be another way of doing it, though. From the article:

"Now, simple rows of boreholes like those drilled in the field could make all of that obsolete. They appear to work as a “seismic cloak” that could hide a building—or perhaps an entire city—from an earthquake’s deadly waves. “If we drill holes around the building, forget about all your earthquake protections inside the building. We don’t need them anymore,” says S├ębastien Guenneau, the originator of the idea and a physicist at the Fresnel Institute in Marseille, France."

Guenneau accompanies this description with a nifty metaphor to help our understanding. We've all seen heat mirages in the summertime. Air rises from hot asphalt in front of you. The low density of the heated air causes the light to bend and get wavy near the ground. A similar effect happens to seismic waves as they pass through soil with holes drilled in it. The less dense ground distorts and thereby lessens the waves.

A similar approach could be taken at sea with tsunamis. Instead of holes drilled in the ground, there would be a rectangular "carpet" of rods jutting up from out of the ocean. Preliminary studies have shown these rows of rods reflecting waves rather than washing over them. Guenneau states in the article that he would like to place these protective "carpets" near a high-value test subject, such as a nuclear power plant.

Brilliant, eh? I am all set to write an encomium to these researchers but there is a cynical voice that arises in the back of my head, one born of society's main concern: money. As people driven by consumerism before all else, I can already hear the objections of "how much is all this going to cost?" To that, Guenneau replies:

“The cost would remain quite affordable compared to the cost of a nuclear plant which is destroyed or a city which is devastated. You prefer to have a carpet which costs perhaps 10 or 20 million euros than have 50,000 human beings wiped from the surface of the earth.”

Makes sense to many of us, but there will be plenty of others who will undoubtedly say that the materials involved in building such a "carpet" will still be too expensive.

I'm sure there are many ground-breaking concepts just waiting out there, new approaches that could help us adapt to a changing environment or to protect us from environmental dangers we have always faced. Then again, there are all manner of things we could do to prepare for a post-carbon world, but progress on that front appears slow.

All of it comes down to choices we as a society are willing to make and how we define "expensive."



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