Lights Switch
The humble electric lightbulb has been with us for a century and a quarter. Yet now it is on the verge of extinction – and a revolutionary technology is set to take over.
Light emitting diodes, or LEDs, have the potential to replace ordinary bulbs for a vast range of uses, while consuming far less energy.
Conventional incandescent lightbulbs have changed relatively little since Joseph Swan and Thomas Edison patented their first designs in the late 19th century.
They rely on a very simple principle, using electricity to heat a thin filament to very high temperatures, until it becomes white hot and produces light.
But they are also extremely inefficient. Only about 5% of the energy they use is actually converted into light.
In an era of unprecedented energy-awareness, that simply isn’t good enough. On both sides of the Atlantic, sales of incandescent bulbs are being phased out – by law.
The immediate replacement for the incandescent bulb is the Compact Fluorescent Lightbulb, or CFL.
These work in a similar way to neon signs and striplights, with an electric current being passed through a gas-filled tube.
They’re much more efficient than incandescent bulbs – but they also have some significant drawbacks.
They’re expensive to produce, they contain toxic products, notably mercury, and they take time to warm up, so they don’t provide a strong bright light the moment you throw the switch.
This is where LEDs come in.
Light emitting diodes have been around since the 1960s. They produce light when an electric current is passed through a piece of semiconductor material.
Until relatively recently, they were only used in a limited way, for example as dashboard lights in cars or as on/off lights on electrical goods.
But in recent years the technology has improved vastly. High power LEDs are now capable of providing large amounts of light, while using relatively little energy.
The range of uses for LEDs is growing rapidly. They are increasingly found in traffic signals, as streetlighting, in vehicles and in display cases in shops.
In October 2008, the US department of energy released a report which looked at how much electricity would be saved if LEDs were used to their full potential in 12 niche areas like these.
The results were remarkable. It concluded that electricity savings of up to 212 trillion watt hours were possible. That’s broadly equivalent to the output of 27 coal fired power stations.
The DoE conluded, “Solid state lighting has the potential to revolutionise the lighting market through the introduction of more energy efficient light sources”.
But this is only part of the story.
The study focused only on how LEDs could be used in niche markets, such as traffic lights and electric signs, while its calculations were based on existing technology.
Yet LED technology is improving rapidly. As it becomes cheaper and more suited to users’ needs, it will inevitably move beyond those niche markets.
LED units are already being used to provide some forms of lighting in the home. It is highly likely that before long they will become the logical replacements for conventional incandescent bulbs.
And increasingly LEDs are being used to replace old-style fluorescent tubes, in offices, advertising signs and streetlights. In short, the technology is rapidly becoming mainstream.
So the future for LEDs could soon be very bright indeed.
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