Researchers at MIT have shown that by surrounding the filament with a special crystal structure they can bounce back the energy which is usually lost (see article here).
This seemed interesting, and brought forth a comment from Peter Glaskowsky, another CM advisor, expressed some skepticism:
Some of this story is simply false to fact, but other parts are correct.
For example, LEDs with CRI values over 90 (and up to 97) are widely available, and some of these also provide high-quality red tones (the part of “warm” that is particularly noticeable to some people).
On the other hand, it’s correct that LEDs with high CRI values are only around 14 percent efficient, as the story says, so if the MIT solution can increase this figure to 40%, that could be good.
But MIT has only achieved an efficiency level of 6.6% and these researchers haven’t even identified a theoretical basis for surpassing 20% efficiency—about where the best LEDs stand today—so they’re a long way from claiming any real advantages.
Also, the technology behind this invention looks expensive and has some limitations. First, the reflectors are made using semiconductor-like materials and processes—up to hundreds of stacked layers of exotic materials that have to be made with high precision or the product won’t work right. There’s no precedent for using these processes on highly curved surfaces, either.
Ultimately it isn’t at all clear to me that it will ever be possible for this technology to surpass the combination of cost, efficiency, and color quality offered by LEDs, which is not the conclusion invited by MIT’s press release.
I’ve seen many of these factually questionable and unjustifiably optimistic MIT press releases in the past, suggesting this is either a deliberate strategy or just a quirk of someone in their press office who really ought to find something else to do for a living. MIT does plenty of good work; there’s no need to hype it past all scientific justification.
Your CMR editor has a supply of incandescent bulbs, many bought before some sizes were outlawed by the US government (info on incandescent bulb ban here). There are several places in my house where the lights tend to be on all the time (partly due to need, partly due to laziness). Here’s my thoughts:
I have started a slow process of replacing my incandescent bulbs (and CFL’s) with LED lights (for A19 base 2700K bulbs, I got these http://amzn.to/1PsxE8h ; 6 pack for about $21.00). I have a full set of six on the light fixture above the dining table, just a few feet away from my usual spot in the living room. That light is always on, even during the day. They are 60W equivalent, and are brighter than the incandescent bulbs, and the CFL that I tried in the same fixture. And they are full-bright immediately, rather than needing the warm-up period of CFLs.
I have also started using LED bulbs in various ceiling ‘can’ fixtures (65-watt equivalent, BR30 bulbs, use 7 watts), using them as the old bulbs (incandescent and CFL) have failed. They appear to provide more light, and again do not need the warm-up period of CFLs. The 65-watt LED bulbs will eventually replace the older BR30 bulbs in the entire house, especially in the kitchen, where the slow-brighten time of CFLs is problematic.
The 65-watt BR30 bulbs were purchased from Amazon http://amzn.to/1Psxrlp , 6 for $35, with free shipping courtesy of Amazon Prime. They are ‘dimmable’. I notice they are out of stock at the moment, but LED bulbs are available in many places. (Some local utilities are also subsidizing LED purchase.)
So far, pleased with them. I am assuming that they will be a positive effect on my electricity bill. And using the bulbs in the family room, at 7 W each instead of 65W, will allow that circuit to be powered by my generator during any power outage. (That light circuit is on the same circuit as the TV, which I plan to power during any outage with my generator.)
Advisor David Em is also an LED bulb proponent:
Last year I bought fairly inexpensive dimmable full-spectrum LED spots for the studio. I love them.Also happen to be reading Oliver Sacks’s “Uncle Tungsten” [Amazon link ] at the moment, which has some interesting discussion of the history of light bulbs.
What do you think? Are you moving towards LED bulbs, or are you holding out with incandescent? Or are CFL’s your choice? Let us know in the comments.