Race to produce more light from less energy

Press, 15 April 1980, Page 22

Race to produce more light from less energy

From the “Economist,” London

The race to corner the world’s energy-efficient lightbulb market is on. Last June, General Electric of America announced the Elec-, tronic Halarc bulb.

This month Philips of tue Netherlands launched its new “SL” bulb. Both bulbs arc intended to replace ordinary incandescent ones. The General Electric bulb will not be available to the public until at least 1981 — there are manufacturing problems still to be resolved —while Philips’s “SL” bulb is already on sale. The SL bulb fits into existing lampholders, lasts five times as long as incandescent bulbs, and consumes only 18 watts of electricity to produce the light equivalent to that from a 75watt incandescent bulb, (Only a proportion of the electricity consumed by a lightbulb is converted into light; the rest dissipates in th'’ form of heat).

Philips claims that,; in Europe, the replacement' of incandescent with SL bulbs in 10 per cent of domestic uses and 25 per cent of industrial and commercial uses would save round 14J billion kilowatt hours of electricity a year, worth roughly $l-billion at today’s prices. Lighting efficiency should be measured in lumens -per watt. : The first lightbulbs had an output of only 1.4 lumens per watt.- Even now, normal incandescentbulbs have a luminous ' efficiency of only 12-15 lumens per watt , By contrast,/,. fluorescent tubes .have an/output of 80 or 90 Tumens per watt. Unsurprisingly, Philips’s SL

bulb is a development of the familiar fluorescent tube. Fluorescents produce light by passing an electrical current through a gas. The resulting ultra-violet light is converted into white light through coating the inside of the tube with a special powder.

Philips’s breakthrough has involved the miniaturisation

of the fluorescent .tube, and the development of new phosphors to coat the tube. These have improved the colour of the light, making it-very similar to that from ordinary incandescent bulbs. Will the public buy? Philips calculates that each bulb should save $2O during its 5000-hour life. But the initial cost of a bulb will be $16.50,