Sulfur Lighting No Longer on Track

Ten years ago we covered sulfur lighting, then a new light source that offered promise for high efficacy (about 100 lumens per watt), good color rendition (CRI of 80), highly concentrated light (130,000 lumens from a light source the size of a golf ball) lending itself to light-tube distribution, very long lamp life, and avoidance of mercury (which is used in fluorescent and HID lighting)—see

EBN

Vol. 4, No. 4. Fusion Lighting, Inc., had just installed high-visibility prototypes at the U.S. Department of Energy (DOE) headquarters (at the Forrestal Building) and the National Air and Space Museum, both in Washington, D.C., and was moving ahead full-steam with product development. As an indication of the promise, at the Forrestal Building DOE replaced 240 175-watt mercury-vapor HID lamps with a 240' long (73 m) 10"-diameter (250 mm) light tube powered by two sulfur lamps, one at each end; this system produced four times as much light at one-third the cost, compared to the lights it replaced. Indeed, the technology looked extremely promising.

Alas, it wasn’t to happen. Fusion Lighting closed its doors in early 2002 after churning through tens of millions of dollars in venture capital. According to the past president of the company, Leslie Levine, “Fusion Lighting is closed down, and all that is left are a set of patents, including those on the sulfur lamp.” Levine is not aware of any company making sulfur lamps today, though Fusion Lighting has licensed other lighting technology to LG in Korea. He told

EBN that they are willing to sell the intellectual property rights to a company that would carry Fusion Lighting’s technology forward. Though the manufacturer is gone, three or four sulfur lighting installations are still operating in the Washington, D.C., area, according to James Broderick of DOE. (The Air and Space Museum and Forrestal prototype installations were replaced with production models in 1996 and ’97.)

According to Steve Johnson, Lighting Research Group leader at the Lawrence Berkeley National Laboratory (which carries out a lot of DOE’s lighting research), sulfur lighting is a “difficult combination of lamp and source to make work.” In particular, the life of the power source (a magnetron, or microwave generator) was a significant technical obstacle. He told

EBN, however, that developments with silicon-carbide power chips used for radar systems have a frequency range close to that of microwaves and show promise for overcoming some of the limitations that were experienced with Fusion Lighting’s sulfur system. DOE is not currently funding any sulfur lighting research.

Sulfur lighting is down but may not be out. Johnson has seen product literature from a Chinese company claiming to have a sulfur lighting source on the market, though he hasn’t seen the actual product. A Web search found that research is being actively conducted on a “microwave sulfur lamp” at the Institute for Electric Sources at Fudan University in China. It is not known how similar this technology is to that of Fusion Lighting.

 

– AW

For more information:

Illuminating Engineering & Light Sources Department

Institute for Electric Sources

Fudan University

Shanghai, People’s Republic of China

light.fudan.edu.cn