Incandescent light bulbs may put out a warmer-looking, more familiar type of light than LEDs or compact fluorescents, but they're far less efficient – the majority of the energy they use is wasted, mainly in the form of heat. Technology may save them yet, however. Scientists at MIT and Purdue University have developed an ultra-efficient new incandescent bulb that reuses the heat it gives off, converting that heat into more light.
With traditional incandescent bulbs, both visible and infrared light are created by heating a tungsten filament, causing it to glow. Both wavelengths flow unimpeded out into the room, with the infrared doing nothing other than dissipating as heat.
In the case of the new two-stage incandescent, however, the filament is surrounded by structures known as photonic crystals.
Made from abundant elements and manufactured using conventional material-deposition technology, these crystals allow visible light to pass through, but reflect the infrared back onto the filament. This helps keep the filament heated, glowing and emitting more visible light, while using much less electricity than it would otherwise.
The bulb could conceivably score very high when it comes to luminous efficiency – this is a measure of how well a light source produces visible light. While regular incandescents have a luminous efficiency of 2-3 percent, with compact fluorescents coming in at 7-15 percent and LEDs at 5-15, the two-stage incandescent could reportedly manage up to 40 percent once developed further.
The current proof-of-concept model sits at around 6.6 percent, although even that figure is in line with some LEDs and fluorescents, and is three times better than conventional incandescents.
A paper on the research was recently published in the journal Nature Nanotechnology.
Source: MIT
I googled and the max luminous efficiency (100%) is 683 lm/W meaning 6.6% is 45 lumens/watt and 40% would be 273 lumens/watt.
Popular CFL's are > 60 lumens/watt and even inexpensive LED's are now over 80 lm/watt. The good LED's are passing 100 lumens/watt and Cree broke 300 lumens/watt with LED in the lab in March 2014 which puts it ahead of theoretical maximum of 40% efficiency listed above.
So basically even ignoring costs/complexity the 6.6 efficiency they were able to achieve in a lab environment is already still behind disposable priced CFL and LED's on the market today.
My Nanoleaf Bloom from last year was expensive but it's 2.4 times their lab tested efficiency. It's an improvement but incandescent bulbs are unlikely to make a comeback. In the time they improve LED technology isn't going to stand still either.
There are literally hundreds of types of LED lamps. Some of the latest designs replicate vintage light bulbs, as the LED elements now have the appearance of a glowing tungsten filament. They can also be dimmed. The wattage is low, by comparison even with the ghastly fluorescent lights, and of course they are promoted as lasting for many thousands of hours. A 10 W LED bulb is roughly equivalent to a 60 W incandescent lamp. See the savings in electricity. My daughter's kitchen has 10 50 W halogen spotlights. I am trying to persuade her to fit LED replacements! I did in fact buy her some but the bulbs were a bit longer than the space she had in the ceiling!I am trying to find a suitable lamp for the job. By the way the replacement lamps would probably be 6 to 7 W
The prices are now very affordable. I do not work for the company, but have bought a number of different bulbs from banggood.com I have had a few failures, but the company has sent a free replacement when necessary. Another company is myled.com
Why compare what it could reach with what LEDs actually reach? Why not compare it to what LED's could reach? LEDs will reach 200 lumens per watt in less than a decade. At 100 lumens per watt it already is way ahead of incandescent lights.
Homes of the future should be wired to have PoE wall outlets. Things like controllable bulbs, security cameras, temperature sensors, smoke/CO2 detectors, smart TVs, and even wireless access points become incredibly simple to connect from that point forward.
Hopefully this is something more businesses embrace to help lead the way for the consumer market.
Why do this? Well humans have evolved to be active during daylight hours so our eyes are most efficient at the wavelengths of the solar spectrum with the highest energy per wavelength, at sea level and after the considerable absorbtion at longer and shorter wavelengths by the water vapour and comparatively small net total from CO2. (This is why sodium lighting is effective and No, I am not a climate change denier, though the significance of this is rarely treated honestly by the global warming gurus.)