|
Written by Thomas Anderson
|
|
Friday, 21 January 2011 15:09 |
 There is a new light bulb out called an ESL (or electron stimulated light). They are essentially CRTs (cathode ray tubes), or little television monitors, without the signal processing and electron gun aiming hardware so they just put out a single color on the "screen". The claim is that they are highly efficient while also putting out a full-spectrum of light similar to incandescents. However, while they claim up to 90 on the Color Rendering Index (CRI), compact fluorescents (CFLs) and light-emitting diodes (LEDs) aren't all that bad anymore. In the past they had a CRI of around 60, but modern ones are above 80. Also, there's a reason why we've replaced CRT televisions with LCD screens lit by fluorescent or LED lights... it provides a better form factor and much more efficiency. ESLs are directional like LEDs, however you can put multiple LEDs in a single bulb to get multi- or omni-directional light. ESLs will only be useful for flood or can lighting. And they’re quite expensive too considering their lifespan.
I made up a chart comparing the four types of light bulbs (rated at 40W-equivalent luminosity):
| | Incandescent | ESL | CFL | LED |
| Output (Lumens) | 450 | 372 | 520 | 450 |
| Color Rendering Index | 100 | 90 | 80 | 82 |
| Contains mercury | No1 | No | Yes | No |
| Construction2 | glass | glass | glass | solid state |
| Lifespan (hours) | 2,000 | 10,000 | 10,000 | 50,000 |
| Energy (Watts) | 40W | 12W | 10W | 8W |
| KWh used over 50k hours3 | 2,000 | 600 | 500 | 400 |
| Purchase Cost | $0.60 | $13.00 | $3.00 | $18.00 |
| Bulbs needed for 50k hours usage | 25 | 5 | 5 | 1 |
| Equivalent 50k hour bulb expense | $15.00 | $65.00 | $15.00 | $18.00 |
| 50k hour electricity cost4 | $200.00 | $60.00 | $50.00 | $40.00 |
| TOTAL COST5 | $215.00 | $125.00 | $65.00 | $58.00 |
1 although incandescents don't actually contain mercury in the bulb, the coal used to power them does, and about the same amount of mercury in a CFL bulb is released into the atmosphere during the lifespan of an incandescent bulb -- far, far less is released from the coal needed to power an LED
2 most types of bulbs use a vacuum contained in glass, which is fragile, whereas the solid-state construction of LED lamps makes them shock and vibration resistant
3 50,000 hours, the rated lifetime of an LED bulb, is approximately 5 years, 8 and a half months straight; if the bulb is on for 6 hours per day, it's about 22 years, 10 months
4 grid-powered at 10 cents/kilowatt-hour -- this may be more or less than your rate
5 cost of bulb(s) and electricity (at current rates) for 50,000 hours of full brightness
Perhaps the technology will improve for ESLs in order to reduce their cost, extend their lifespan, and improve their efficiency, so it's worth keeping an eye on. But I won't be buying any myself in the near future.
|
