Nov 14, 2021 05:43 PM
https://knowablemagazine.org/article/tec...our-cities
EXCERPT: . . . A new generation of luminescent materials has the potential to cool cities by re-emitting light that would otherwise be converted into heat. They might also cut down on energy use, since luminescent sidewalks, glowing road markers or even glowing buildings could replace some street lighting. Already, some cities in Europe have installed glowing bicycle lanes, and some researchers have studied using glowing paint for road markings.
“It’s better for the environment,” says Paul Berdahl, an environmental physicist now retired from Lawrence Berkeley National Laboratory in Berkeley, California. “If the technology can be improved, we can use less energy.… It’s a worthwhile thing to do.”
The Bologna Stone, a form of the mineral baryte, fascinated natural philosophers at the time, but was never especially useful. But in the 1990s, chemists developed new types of persistent photoluminescent materials, such as strontium aluminate, that maintained a strong glow for hours after exposure to light. Most of these new materials give off a blue or green glow, although a few glow yellow, red or orange.
Such photoluminescent materials work by “trapping” the energy of a photon and then re-emitting that energy as lower-wavelength light. Sometimes the light is emitted immediately, such as in a fluorescent light bulb. Other materials, which are called persistently luminescent, store the energy longer and emit it more slowly.
These materials that glow strongly for hours open possibilities, such as “glow-in-the-dark” cities lighted by luminescent pavements and buildings. Since 19 percent of all global energy use is for lighting, and in Europe about 1.6 percent specifically for street lighting, the potential energy savings are large, write building engineer Anna Laura Pisello and colleagues in the 2021 Annual Review of Materials Research.
One problem with the approach is that most luminescent material won’t glow all the way through the night. Better materials could help solve that problem... (MORE - missing details)
EXCERPT: . . . A new generation of luminescent materials has the potential to cool cities by re-emitting light that would otherwise be converted into heat. They might also cut down on energy use, since luminescent sidewalks, glowing road markers or even glowing buildings could replace some street lighting. Already, some cities in Europe have installed glowing bicycle lanes, and some researchers have studied using glowing paint for road markings.
“It’s better for the environment,” says Paul Berdahl, an environmental physicist now retired from Lawrence Berkeley National Laboratory in Berkeley, California. “If the technology can be improved, we can use less energy.… It’s a worthwhile thing to do.”
The Bologna Stone, a form of the mineral baryte, fascinated natural philosophers at the time, but was never especially useful. But in the 1990s, chemists developed new types of persistent photoluminescent materials, such as strontium aluminate, that maintained a strong glow for hours after exposure to light. Most of these new materials give off a blue or green glow, although a few glow yellow, red or orange.
Such photoluminescent materials work by “trapping” the energy of a photon and then re-emitting that energy as lower-wavelength light. Sometimes the light is emitted immediately, such as in a fluorescent light bulb. Other materials, which are called persistently luminescent, store the energy longer and emit it more slowly.
These materials that glow strongly for hours open possibilities, such as “glow-in-the-dark” cities lighted by luminescent pavements and buildings. Since 19 percent of all global energy use is for lighting, and in Europe about 1.6 percent specifically for street lighting, the potential energy savings are large, write building engineer Anna Laura Pisello and colleagues in the 2021 Annual Review of Materials Research.
One problem with the approach is that most luminescent material won’t glow all the way through the night. Better materials could help solve that problem... (MORE - missing details)
