LED Light Bulbs and Tungsten Filament

A bit more on economics: an Edison bulb (and all other pre-20th century light sources) is essentially a heat source that produces a little bit of light. A “65 Watt” Edison bulb produces about 700 lumens (a lumen, “lm”, is a unit of visible light power). If you had perfect conversion of electricity into light, you would need only 1.0 Watt (“W”) of electrical power to produce 700 lm. So, an Edison bulb is 1.6% efficient. For such a widely deployed technology, this is amazingly bad. But Edison bulbs are much better than the kerosene lamps they replaced …

A comparable LED bulb* consumes 13 W and produces 730 lm, which is 5.2x better efficiency than an Edison bulb, but still only 8%. The theoretical efficiency of an LED is about 30%, but commercially available LED materials are ~16%, and making a light bulb involves a power supply, phosphors, a protective container, etc., all of which dissipate energy.

Why are LEDs better? Edison bulbs function by making a Tungsten filament very hot, and a hot object glows: radiating energy on a broad spectrum of wavelengths, only a small part of which is visible to the eye. The rest of the radiated energy is mostly heat.

LEDs function by driving electrons across a junction between two semiconductor materials in which electrons move at different energy levels. When the electrons cross the junction, they drop from the higher energy level to the lower one, and the energy each electron loses when it drops takes the form of light to a large extent. The color of the light is mathematically determined by the energy level difference. So all of the light produced by an LED is the same color, and LEDs can be designed to produce light in the visible range. This precise conversion to one color is why LEDs are referred to as “digital light”. There is some waste heat caused by inefficiencies within the LED, however, the net result is a big gain in the percentage of electricity converted to visible light.

This digital precision creates a problem, too. Our eyes prefer full-spectrum analog light: what you get from a light bulb, a fireplace, or the sun. LED bulbs use a mix of phosphors (materials that absorb light and re-emit it at different colors) to convert the single color from the LED into multiple colors that mimic the spectrum, imperfectly. I find today’s LED bulb light pleasing, but my wife thinks the same light looks too orange.

LEDs are also long lived because they do not operate at the high temperatures that degrade the filaments of Edison bulbs. The LED itself has an expected life of about 50,000 hours (six years) of continuous use. Its power supply is less robust, so LED bulbs are usually rated for 25,000 hours. How long they last in practice is TBD, however: I have not used any for 25,000 hours. Edison bulbs are good for about 2,000 hours.

Here is how the dollars work out today. This example is for flood lights of the type used in down lights (“cans”), which is most of what we have in our house (pictured above). If you use a 65 W Edison bulb heavily (6 hours per day, 2,200 hours per year), it consumes $21.50/year of electricity (@ $0.15/kWh). The LED bulb uses 80% less electricity and lasts 11 years, so the electricity savings is $17.20 per year, plus a replacement Edison bulb @ $2, resulting in $19.50 of savings. The LED bulb costs $27 at Home Depot. So you get payback in 1.5 years and expect to keep saving for quite a few years beyond that. If the bulb is less used the payback is longer but the ROI is still good.

 

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Lakeside Set for a Showdown with the 2013 World Darts Championships

IT’S New Year and that can only mean one thing – darts is back!

The world famous Lakeside stage is set to celebrate the 40th anniversary year of the British Darts Organisation with the 2013 Lakeside World Darts Championships, starting on Saturday.

Players from over 30 countries around the globe have competed to qualify in the final field of 32 men and eight women over eight days of top tungsten action.

In addition to extensive coverage on BBC Sport for the 36th consecutive year, the tournament will also be seen on satellite channel ESPN as well as Eurosport and Eurosport Asia, combining to produce the biggest TV audiences for darts in the world.

The bookies favourite this year is England’s Stephen Bunting, who more than justifies his No.1 seeding having won his first major title, the Winmau World Masters, in October, and the Zuiderduin Masters in Holland last month.

Bunting takes on Lakeside debutant Jamie Wilson on Sunday in the opening match at 1pm.

At 56, three-times champion Martin Adams is the oldest player in the tournament, and the No.2 seed begins his 20th consecutive Lakeside campaign against the youngest, Dutch star Jimmy Hendricks, just 18. That match is also on Sunday with a 3pm start.

Dutch star Christian Kist won here as a qualifier ranked No.74 in the world 12 months ago, epitomising the magic of Lakeside by arriving largely unknown and leaving with the famous trophy and a cheque for a life-changing £100,000.

Also defending their Lakeside title is Women’s world champion Anastasia Dobromyslova, who added to her 2008 crown with victory over Trina Gulliver in last year’s final.

The Russian returns at 7.30pm on Sunday when she plays Lorraine Farlam.

It’s a complete sell-out at Lakeside, play gets underway on Saturday at 1pm.

 

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Camouflage Rings the Latest Addition to Online Retailer

Modesto, California, United States – Titanium-Jewelry.com, a leading online retailer of men’s wedding bands, tungsten rings, titanium rings and unique contemporary jewelry designs for men and women, has now announced the addition of new rings, camouflage wedding bands. The rings are made of either titanium or tungsten as the base material.  The surface of the each ring has an artistically unique camouflage design, then an industrial epoxy coating is applied creating a hardened acrylic enamel.
 
Scott Mackey, COO of Titanium-Jewelry, says “Camo Rings are becoming very popular with younger men who tend to be outdoorsy, hunter types.  Each ring has a unique pattern and they are priced in everyone’s budget.”
 
An outdoorsman with an adventurous spirit and an appreciation for nature would be the ideal candidate to wear one of the camo rings from this line. The classic look of titanium wedding bands joined with the manly look of camouflage is a winning combination.
 
In business for more than 20 years, Titanium-Jewelry.com has a reputation for carrying beautiful, award winning wedding bands and jewelry that is perfect for men and women looking for both contemporary and classic design. Titanium-Jewelry.com specializes in men’s titanium rings, tungsten rings and cobalt rings combined with the precious metals and diamonds.

 

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BARRY HEARN Reckons Darts is Going Global

Phil Taylor's Ladbrokes PDC World Championship final victory over Michael van Gerwen was beamed live to South Africa for the first time.

Coverage from Alexandra Palace has also broken new ground this year in Eastern Europe and the USA.

PDC chairman Hearn says the top players stand to cash in on the new wave of interest, with prize money already set to be increased for the 2014 tournament.

Next year’s winner stands to collect £250,000 — a whopping 25 per cent hike on this year.

Hearn said: “The world seems to be opening up because 2012 has been a massive year for us.

“Apart from the fact that NBC are showing regular darts on their sports channel in America, we have had live coverage for the first time in Eastern Europe, through Hungary and Romania.

“These are entirely new areas for us, the Asian coverage is growing and it is becoming a really global sport.

“If you are new to the sport, you can follow the game quite quickly and the atmosphere the fans give, that comes through on the television coverage.

“I am finding that people are incredulous about the atmosphere — even more so than the darts.

“They cannot believe that there are thousands and thousands of people going crazy watching an indoor game that has always been associated with pubs, that has suddenly become working man’s golf. Darts has become that.

“We have been stuck in the traditional sports for years — football, cricket, rugby. But all of a sudden, darts has come up on the blindside and is creating atmospheres and TV ratings that surpass any other sport apart from Premier League football.

“We are hearing record audiences in Germany, Holland, the UK. This morning I had a phone call that we want to go live with the final in South Africa — we have never done anything in South Africa.

“People have looked down their nose for too long at traditional, working-class pastimes that suddenly become major sports.

“People don’t see Premier League footballers walking down the street because they are too busy driving their Ferraris. The appeal of this sport is that ordinary people are achieving their dreams and people can associate with that.

“It is cheap to play, there is no barrier for entry — you don’t have to be a member of a golf club or have an expensive set of clubs.

“All you need is ability and dedication — but we have the characters who are transgressing the normal barriers of sport because everyone can associate with it.”

‘The Power’ Taylor, 16 times the world champ, has gone from the dole to being a multi-millionaire thanks to his talent with the tungsten tips.

Hearn said: “I don’t think the bubble will burst. I’ve always felt we were a work in motion, a jigsaw being put together and over this tournament a few more pieces of the jigsaw have gone into place.”

 

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Photonic Crystals Reinvent Tungsten Light Bulbs

Photonic crystals of tungsten emit visible light but without the same wasteful emission of infrared, say researchers aiming to reinvent the light bulb.
 
Photonic crystals are nanoscopic structures designed to channel light of specific wavelengths while blocking other wavelengths.
 
This ability to control and filter light with great efficiency makes them hugely useful for applications such as increasing the efficiency of photovoltaic cells by absorbing light at certain optimal wavelengths.
 
Today, Sergei Belousov and buddies at the Kintech Lab in Moscow and a number of friends at the GE Global Research Center in New York state,  say they have another application for photonics crystals. They’ve worked out how photonic crystals can dramatically improve the light emitting efficiency of tungsten in the hope of reinventing the light bulb.
 
Tungsten bulbs have had a bad press, to say the least. Tungsten has a high melting point (3695 K) and so can be heated until it glows without melting. The problem is that only 5 per cent of the light it emits is visible, the rest being infrared, which simply goes to waste.   With an efficiency of only 5 per cent, tungsten bulbs have rapidly fallen out of favour.
 
The question Belousov and co set out to answer is whether they can engineer the nanostructure of tungsten to create a photonic crystal that emits visible light while suppressing the emission of infrared light.

They theoretically studied the properties of several structures, such as nanoscopic tungsten log piles and spheres embedded in another medium. While tungsten log piles make little difference, tungsten spheres just a fraction of a micrometre in radius do just the job, emitting light mainly in the visible region of the spectrum.

Belousov and co then tested their idea by making a tungsten photonic crystal of the required design and measuring the amount of light it emits at different frequencies. They say the new structure emits far less infrared light and has an efficiency of 15 per cent, significantly higher than the bulk material.
 
That’s a significant improvement and improvements on this will surely be possible. But whether it will be enough to trigger a tungsten revolution in light bulbs is open to question. The current generation of compact fluorescent bulbs can match the light output of a 100 Watt tungsten bulb using less than 30 Watts and LED lights can do it using less than 20 Watts.
 
If Belousov and co want to put tungsten back into light bulbs, they’ll have to beat some stiff opposition first.

 

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