I don't think that SiC semiconductors are anything particularly new. And, according to
when applied to LEDs, SiC seminconductors are used to create blue LEDs. That yellow colored phosphor is what changes to light to white.
Here are the types of semicondictors used to create different colors, according to that URL:
"Silicon carbide (SiC),
indium gallium nitride (InGaN), and zinc selenide
(ZnSe) produce blue LEDís.
(GaP), and gallium nitride (GaN) produce green
"Gallium arsenide/phosphide (GaAsP) produce
red, orange and yellow LEDís.
arsenide (AlGaAs) produces red and infrared."
It goes on to say that white light can be made by combining red, green, and blue, although I'm pretty sure that's the more expensive way of making a white LED. The cheaper approach is just to use a blue plus a phosphor.
Given the cost of the bulbs, the savings can accrue over time but with the limited lifetimes (power electronics typically) I am not sure the bulbs will ever pay for themselves based on electrical usage. I do know that in a number of applications they are very nice - quick to start and energy efficient (more for the PR and customer experience than real savings). Some companies will want to jump on the bandwagon just for the green-ness of the bulbs, again maybe more PR than anything else.
I think they do pay for themselves even at the current prices. I replaced 3 50W halogen bulbs on my kitchen hood with 8W LED lamps which are brighter which means I can operate them at a lower dimmer setting. Bulbs were $20 each.
savings per year at 5hrs a day for 360 days at 11c per kWh = $7. so return is in 3 years approx.
This is conservative since we now keeps the main kitchen lights off most of the time since all we need is lights over the stove at least in the daytime. Earlier, we had to turn all the lights on for an extra 65W for 5x13W CFLs.
I think that having any new appliance that requires LESS power than what it replaces, for a change, can only be beneficial overall. That in itself is worth money.
Obviously, this can be taken to extremes, but it seems to me that it's wrong to dismiss these improvements, only on the basis that overall acquisition and operating costs are perhaps not quite low enough. Would anyone be so cost-obsessive, say, about their food? Never mind clothing?
Think of it this way. Flat panel TVs, especially plasmas, require considerably more power than the CRTs they replaced. Thank goodness we have LED lighting just around the corner that can actually compensate for this.
I agree with you to some extent. I am concerned that in the cost sensitive regions of the world (e.g. India) it might take some more time to accept the LED lamps. Going with the experience with the CFL lamps: the CFL lamps were costly (they are still) when launched compared to incandescent lamps or the fluorescent lamps, but over last 5-7 years CFL lamps have become popular in India. It was partly because of your logic, some people were not so cost obsessive, may be because the cost of CFL lamps justified over the energy saving over the incandescent lampsÖsome due to the spreading of the awareness, marketing etc. But the cost of LED lamps is too high compared to the benefits that could be explained to these people.
Our electric utility companies distributed many CFL bulbs for free, or at greatly reduced cost when they first came out. The fact that each CFL contains a small amount of mercury makes them much less desirable than LED's when you take into account the disposal cost.
This is a good advancement. The move to LED lighting will happen once it is better (cheaper) than what is available. The price of LED bulbs will continue to come down as the volume increases and the advancements in the science continue. I look forward to moving to that technology.
The LEDs are supposed to have a life of 25 years. If the associated electronics also lasts that long then LEDs will become a good lifetime investment for lighting and saving a huge amount of energy cost over their lifetime
Good point. Also because, LEDs tend to become gradually dimmer with age. Although this happens so gradually that people don't usually notice. So "lifetime" needs to consider replacement just because of lost lumens.
We have noticed this dimming over time with CFLs, more pronounced in the ones with very small twisty part, enclosed in a light bulb-like glass cover.
Cree 231 Lumen Per Watt LED Shatters LED Efficacy Records Ė was the news reported on May 9, 2011.
Now, it reports 148 LPW as an achievement. ???
Can we believe lifetime estimates? When CFL bulbs were launched, they were touted as having 7 year lifetimes. Not including the infant mortality (5% of bulbs failed out of the box), I'd guess that 25% failed within a year. While they all got replaced at no cost, the mismatch between reported and actual lifetimes was striking. At least the CFL bulbs were cheap. LED bulbs are not.
We haven't anything remotely close to that. The CFL brands we buy are Sylvania or UtiliTech, which are sold at Best Buy. We've had much better luck than what you describe.
Basically, one failure that was premature, within maybe less than a year, one failure in a couple of years (which is also premature, in my book), and the rest keep soldiering on for many years.
As to going to laser lights, interesting concept. I wonder if the coherent nature of laser won't create some weird phenomena?
Can we skip LED lights and go straight to 4 color diode laser white lights? "Photonics Spectra" (Jan 2012, page 20) reports that Sandia National Laboratory has produced white light that is superior in quality to current lighting technologies. They claim diode laser lights can also scale to brighter level than can be achieved with LEDs (which lose efficiency above 0.5 amp currents).
I have had somewhat the same results as DrQuine with CFL failures at home. In 2 years, I have replaces maybe 1/2 dozen bulbs out of the 30 or so that I have in service.
If one researches, it appears that the failures are due to the electronics associated with start-up.
In order to eliminate these issues, is there any effort to start wiring houses with DC for lighting? We already have DC for doorbells. This would be an easy extension, and would eliminate the cost of the start-up circuitry, and the associated failures.
??? Wouldn't it be infinitely less disruptive (and I mean that pejoratively) to stick diodes in the CFL instead, if they prefer DC?
DC house current would mean that any appliance that doesn't require strictly 115 V would have to have a switching power supply. Not to mention, the electric utilities would have to co-locate gymongous rectifying circuits where they now have the final distribution transformers that go to 230 VAC. Which means, huge changes all over the distribution network.
Not a trivial change.
The decision to go AC vs DC was made a long time ago. Of course, we would not go DC over the distribution network. However, we COULD have a low voltage supply and wire the light switches with a smaller guage wire, needing less robust switches. Perhaps a not trivial reduction in wiring costs, as copper has gone up dramatically.
We would still have the AC for appliances and such.
It would not be a big deal for new houses.
This would mean 2 types of bulbs- DC for new, AC for old. This could be a show stopper due to manufacturers probable unwillingness to have 2 types. But, if LED is the way of the future, why not use it as close to the "raw" state as possible? Cheaper for product, less manufacturing cost, less copper cost, less wiring installation cost. And, less high voltage AC in the walls
(BTW, I previously said DC for doorbell, incorrect. It is 12VAC, I think)
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