While we’re all waiting for the next Star Trek movie to unspool at the local theater, here’s a little Trekkie-style global warming solution to ponder: if you beam enough excess heat from the Earth into outer space, will you blow up the Universe? We’re just asking because a research team from Stanford University has come up with a new ultrathin material that literally beams heat away from inside of buildings, up through the atmosphere, and out into space.
Those of you familiar with the early Star Trek episodes may recall that beaming things out of the way was the go-to solution for troublesome problems, so let’s see how that approach would go to work on global warming.
Global Warming, Cooling Buildings
Air conditioning already sucks up as much as 15 percent of the energy consumed in buildings in the US, and that’s just for starters. Buildings account for a huge chunk of energy consumption, the world is getting warmer, the global population is exploding, and undeveloped economies are developing.
Clearly, the need for an effective, low or no-energy solution for interior climate control is imperative.
Solar powered air conditioning is one emerging solution, but if there are other, simpler solutions that lend themselves directly to structures, then you can save that solar-generated electricity for other things. So, for example, one strategy is to paint your roof white, in order to reflect incoming sunlight away.
The Photonic Solution To Global Warming
The new Stanford “Star Trek” solution takes the white roof thing one step beyond, with an ultra-thin material that both reflects incoming sunlight and “wicks” interior heat out of buildings, sending it out of the earth’s atmosphere.
Keep in mind that the interior heat in buildings is a form of infrared light, and you’re getting the picture. At a certain precise frequency, that heat can be channeled through the Earth’s atmosphere without adding to the global warming load.
The trick is to find the right combination of materials that will reflect incoming heat from the sun while also absorbing interior heat from the building.
Here it is as described by Stanford writer Chris Cesare:
It is made of seven layers of silicon dioxide and hafnium oxide on top of a thin layer of silver. These layers are not a uniform thickness, but are instead engineered to create a new material. Its internal structure is tuned to radiate infrared rays at a frequency that lets them pass into space without warming the air near the building.
All those layers add up to just 1.8 microns thick. Hafnium, in case you are wondering, is a silvery gray transition metal commonly used in the control rods of nuclear reactors, among other things.
The team has just published its findings in the journal Nature under the title “Passive radiative cooling below ambient air temperature under direct sunlight.”
Here’s the money quote from the abstract:
…we introduce an integrated photonic solar reflector and thermal emitter consisting of seven layers of HfO2 and SiO2 that reflects 97 per cent of incident sunlight while emitting strongly and selectively in the atmospheric transparency window.
So far, the labwork has shown that the material can achieve a cooling power of 40.1 watts per square meter at ambient air temperature, when exposed to direct sunlight in excess of 850 watts per square meter.
The next step is to take it for a spin in the real world, so don’t expect to run out and get a can of hafnium-doped roof paint at your local hardware store any time soon.
For that matter, we’d like to see the Stanford team go for the three-fer: a rooftop coating that reflects sunlight, beams out interior heat, and eats smog, too.
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