We in the developed world are preoccupied with the consumer technologies of the 21st century -- ubiquitous high-speed Internet, the iPad, and the Wii Fit. We forget that vast swaths of the developing world have yet to be transformed by a technological upheaval we experienced more than a century ago: the advent of electric lighting. But the latest illumination innovation could change that, bringing not just greater efficiency to the well-wired West but also better quality of life to everyone else.
The first lighting revolution was powered by gas. As gaslight replaced candles over the course of the 18th century, the amount of artificial illumination produced in Britain each year shot up more than 100-fold. In 1879, Thomas Edison began the second lighting revolution when he strung his Menlo Park headquarters with electric lamps using carbonized bamboo filaments. By 1881, a few blocks of southern Manhattan were illuminated by electricity, and the West has never looked back.
Over the past 100 years, there have been many bulb innovations -- including tungsten halogen, metal halide, sodium, and compact fluorescent. And thanks to improved manufacturing and design, it costs 1,000 times less to light a room today than it did 100 years ago.
Still, the vast majority of light bulbs worldwide today --12 billion of them -- use a filament system similar to Edison's. And for all the progress over the last century, these bulbs remain very inefficient. The amount of energy pushed through a filament that actually emerges as visible light is around 2 percent -- most of the rest is lost as heat. This inefficiency is the big reason why in the United States, the power used to light Edison bulbs produces half as much carbon dioxide as the country's car fleet. And it is why governments around the world are so keen for consumers to switch to more efficient bulbs like compact fluorescents.
But the compact fluorescent is yesterday's news. The new technology leader that will spark the third lighting revolution is the light-emitting diode, or LED. The amount of energy converted to visible light by an LED already climbs as high as 14 or 15 percent. That's a thousand times higher than diodes managed in 1968, and considerably better than today's compact fluorescent bulbs. And efficiency is expected to double again by 2020. Diodes have an array of other advantages: they last five times longer than compact fluorescents (50 times longer than the Edison bulb), they are smaller, less fragile, and inert. That all adds up to a lot less expense in manufacture, storage, shipping, and disposal. And it's likely to mean a considerably easier task for those trying to end our addiction to the filament in the rich world.
Whatever its impact on developed countries, however, the real LED revolution will be in the developing world, where billions of people still live without access to networked electricity. Take Africa -- there are about 110 million households in the region without access to the grid, compared with only 20 million who are connected. The most common way for people offline to get light is to burn something. About half of those homes use kerosene lamps for illumination, while most of the rest still use candles. More than one in ten just pile extra wood or dung on the fire if they need more light. In other words, nearly half of African households are stuck using technologies that were largely abandoned in the United States before the Civil War, and most of the rest use a technology that had passed its prime before World War I.