Bright spark invents new light bulb
A low-voltage, longer-lasting and more efficient light bulb promises to cut emissions of carbon dioxide and other greenhouse gases from electricity by 15%, a UK scientist says.
Materials scientist Professor Colin Humphreys, from the University of Cambridge, says the key is using the material gallium nitride, a semiconductor that emits intense light.
Humphreys believes this material, which scientists are creating in the laboratory atom by atom, could be the most important new electronic material since silicon.
He is convinced that using it in a light-emitting diode (LED), a device that emits visible light when an electric current passes through it, could help to curb climate change.
LEDs are already used in digital clocks, bicycle lights, mobile phones and traffic lights. Unlike normal light bulbs, which burn out quickly after about 1000 hours, an LED lasts 100 times longer and fails gradually.
The Japanese firm Nichia used gallium nitride to make the first LED to emit blue light in the early 1990s.
But Humphreys and other scientists around the globe are using the material to develop tiny LEDs that emit a soft white light, instead of the current harsh one, which could eventually be five times more efficient than normal light bulbs.
"At the moment in the laboratory, gallium nitride is three times as efficient as light bulbs but in the next few years it will be five times as efficient, I'm sure," he says.
Singapore, Denver, Colorado and other cities have replaced old traffic lights with LEDs and have seen considerable financial and energy savings, Humphreys says.
"Although the capital cost of LEDs is greater than conventional light bulbs, over 10 years, which is the lifetime of these LED traffic lights, Denver calculates it will save US$5 million [A$6.4 million]," says Humphreys.
But the real savings could come when homes and offices can be converted to LEDs.
"At the moment the white LED is a harsh white. Coaches and cars will soon have white LEDs inside but for homes it will not be very acceptable," says Humphreys.
He estimates it could take about five to 10 years before the technology to produce gallium nitride LEDs with a more subtle white will be available.
But when this happens it could lead to real savings.
In addition to being more economic and efficient, LEDs in the home are also safe because of their low voltage and they never become hot like other light bulbs.
"It's 4 volts but it gives off a brilliant light. One reason they are so efficient is that they stay cold. Light bulbs waste a lot of energy because they get incredibly hot," says Humphreys.
White LEDs won't solve climate change but they could be part of an overall plan to lower emissions of greenhouse gases.
Instead of lighting taking up 20% of electricity consumption LEDs could cut it to 5%, which translates to a 15% saving on overall electricity use.
"You need a number of power station to provide electricity. If you reduce the electricity demand by 15%, you can close 15% of power stations and then you save 15% of the CO2 they emit," says Humphreys.