Bright New Lamp Sharply Cuts Lighting Costs : Technology: Golf-ball size prototype equals illumination of hundreds of mercury-vapor bulbs. First uses likely to be in shopping centers, factories.

WASHINGTON —  The Energy Department has unveiled what it called “a revolutionary 21st-Century” lighting system that uses a bulb of sulfur bombarded by microwaves to produce bright illumination resembling sunlight--and does so at a fraction of the cost of many conventional systems.

The prototype lamp, invented by a Rockville, Md., start-up company called Fusion Lighting Inc. and developed under contract to the Energy Department, consists of a closed quartz sphere filled with an inert gas and a tiny amount of sulfur. One golf-ball-sized sulfur bulb, when irradiated by the kind of compact microwave generator found in ordinary kitchen ovens, puts out as much light as hundreds of high-intensity mercury vapor lamps.

The result is “a major technological breakthrough in lighting,” said Christine Ervin, assistant secretary for energy efficiency.

Commercial products are not expected until some time in 1995, and the first applications are likely to be in lighting extensive outdoor and indoor spaces such as shopping centers, aircraft hangars and factories. Illuminating such areas now costs the United States about $8 billion per year, Ervin said.

The first large-scale use of the lamp is being tested at the department’s Washington headquarters. Two of the bulbs--shining into each end of a 240-foot, 10-inch-diameter reflective plastic pipe--have been installed in the building’s entry area, which was previously lit by 240 175-watt mercury lamps. The new system, which uses less than 12,000 watts, produces four times as much light at about one-third the cost.

A similar test is being conducted at the National Air and Space Museum, where three 90-foot light pipes powered by sulfur bulbs have replaced 94 separate conventional fixtures in one display area. The test units put out three times more light at a 25% saving in cost, Ervin said.

Also important, said Frank A. Florentine, the museum’s lighting director, is that the sulfur bulb emits much less ultraviolet light than traditional devices. UV radiation “is damaging to nearly everything” in the exhibits, he said--notably uniforms and space suits, some of which have already had to be replaced or renovated because they bleached or dried out under the existing lights.

Unlike most other high-intensity lighting sources, the sulfur lamp has no electrodes, which are “the principal limitation to achieving long life in conventional bulbs,” Ervin said. And because there is no evidence that the sulfur reacts chemically to degrade the quartz, the lamp may not wear out for years. “We just don’t know how long they’ll last,” said Fusion Lighting Vice President Kent Kipling.

The DOE expects initial lifetimes of 10,000 to 20,000 hours. The developers expect the sulfur bulb to sustain nearly peak output throughout its life.

The sulfur bulb emits a white light that is optically similar to sunlight. In initial agricultural tests, Kipling said, “plants behave as if they’re seeing sunlight.” NASA has a two-year contract with the company to develop lights for growing plants in space.

Lee Anderson, DOE’s project manager for lighting research, said that the quality of light will be especially important to the increasingly detailed work done in U.S. high-tech factories.