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Hybrid Lighting
Jamais Cascio, 14 Mar 05

Not only can you drive hybrids for green self-satisfaction, you can light your building with hybrids, too. Hybrid lighting, that is, a new technology from the Oak Ridge National Laboratory. The system pipes sunlight throughout a building, providing useful levels of light whenever the sun is out. But on cloudy days, or at night, the lighting fixtures turn on fluorescent tubes to supplement the output -- that's the "hybrid" part. The system can even capture light for power generation. World Science Net has some details, but ORNL has an entire section of their website devoted to Hybrid Solar Lighting.

It's quite the clever bit of technology:

The concept, originated by ORNL's Jeff Muhs, separates and uses different portions of sunlight for two applications, interior lighting and distributed power generation. The concept takes advantage of two facts. First, the luminous efficacy (or light output per unit of energy, expressed as lumens per Watt) of the visible part of the spectrum is more than double that of electric lamps. Second, photovoltaic cells, especially thermo-photovoltaic cells, are very efficient in converting the infrared portion of the spectrum to electricity.
The system will use roof-mounted concentrators to collect and separate the visible and infrared portions of sunlight [...]. The visible portion will be distributed through large-diameter optical fibers to hybrid luminaires. (Hybrid luminaires are lighting fixtures that contain both electric lamps and fiber optics for direct sunlight distribution.) When sunlight is plentiful, the fiber optics in the luminaires provide all or most of the light needed in an area. Unlike conventional electric lamps, they produce little heat. During times of little or no sunlight, sensor-controlled electric lamps operate to maintain the desired illumination level. [...] Independent cost and performance models suggest the overall affordability of solar energy could be doubled or tripled using this new hybrid approach.

Although most of the pages on the ORNL hybrid lighting website date back to late 2002, the current issue of ORNL Review has an update.

Under a contract awarded by the California Energy Commission, ORNL and SMUD [Sacramento Municipal Utility District] in 2005 will install and begin operating an HSL system at SMUD's Sacramento headquarters. ORNL also plans to install an HSL system in a Wal-Mart store in Kauai, Hawaii, to evaluate energy savings and sales trends associated with HSL daylighting.

The real win here is the splitting of the light into visible spectrum and infrared, each used for different purposes. Conventional lighting, even fluourescent, puts out a lot of heat, which in turn requires air conditioning to control. Solar lighting would be an efficiency win even if the infrared portion was simply bled off; using it for power generation makes it all the better. Unfortunately, I didn't find any usable cost of installation estimates on the ORNL site, so it's unclear how long it would take to repay the system costs with efficiency profits. Still, if the costs for hybrid solar lighting systems can be brought to a reasonable level, this strikes me as an enormously useful development for buildings in any location with abundant sunlight.

(Found via Gizmodo)

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Comments

This sounds like a beautiful idea. Combined with LED's, the power generation would be even more efficient and the use of natural light will provide people with the optimum spectrum for health etc. Could we ever see virtual 'windows' with light falling on the building optically piped through walls and released through the ceiling. Keeping people feeling in touch with the outside and saving huge amounts of energy. Very exciting!


Posted by: Daniel Johnston on 15 Mar 05

This is brilliant idea! Recently i had a similar idea to reflect the light from roof top to our kitchen since it is pitch dark without artificial light. I thought of a simple idea using mirrors or some reflectors, but this is real good. I wasn't aware of this project. I just wish this comes into use asap.


Posted by: Gauri on 15 Mar 05

There is a company called SunPipe that makes some simpler things, for when the sun doesn't need to be piped q√ąDp so far. Not sure if it would suit your kitchen.


Posted by: odograph on 17 Mar 05

Perhaps this will replace the household skylights that can be more of a problem than a solution.


Posted by: Erik Ehlert on 21 Mar 05



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