Thursday, November 11, 2010

ESLs - Comparison to other lighting technologies

In a previous post I compared several light sources to understand why a person might choose one over the other.

I bumped into this story on treehugger about Electron Stimulated Luminescence (ESL) bulbs. These lights use an approach like a CRT television to cause a phosphor to light up.



Technical specs for the bulbs are:
  • efficacy = 30.7 lm/W
  • lifetime = 10,000 hrs
  • CRI = 85
  • Color Temp = 2700K, 2900K, 4000K
Other points which the makers heavily emphasize:
  • Fully linear dimming with household dimmers (vs CFLs)
  • Mercury-free, environmentally-friendly materials throughout (vs CFLs)
  • Mount in any orientation [heat issues] (vs CFLs and probably LEDs)
  • Instant on at full brightness (vs CFLs)
  • Lasts approximately 3-6 times longer than an ordinary incandescent bulb
They don't post a price but do say about price: "it will be price competitive against LED products."
If I take "price competitive" to mean 25% less than an equivalent LED bulb, that leads to an expensive bulb... (~$136/klm ESL vs $5/klm CFL).

Plotting that information in the same charts I used earlier gives the following:


The ESL bulb falls into a pretty good space in terms of visual quality. However, its efficacy is quite low compared to the other choices in the space.

Assuming that the FAQ comparison with LED lighting is any indication of how they intend to price the bulbs, then a more serious problem emerges.

The price | performance ratio is quite poor for the ESL. Its lifetime and efficacy values are FAR too low to be priced anything like an LED light. To be competitive, the price would have to be closer to that of a CFL (1/30th the current estimate).
Being Hg free, made from environmental friendly materials, dimmable, providing instant on and lacking heat issues are all very nice but, given it is only about 1/3 as energy efficient as a CFL, a 30x price premium is not warranted ... it would be hard to justify a 2x price premium I suspect.

So unless the pricing comparison with LEDs is highly misleading, ESL is likey to be DOA.
Mass market will buy CFLs because of price | performance.
Specialty applications focused on "green" creds will use LEDs because they are far superior in those aspects.