Wednesday, February 28, 2007

Organic LED / Sphelar Solar Mash Up

Sphelar Solar Cells OLEDs

We were talking about new sustainable technologies at lunch the other day (imagine that) and we came up with a new building integrated photovoltaic and lighting system. The possibilities are limitless.

We have covered Sphelar Solar Cells in an earlier post. Tiny spherical solar cells are joined together on a transparent surface to form a solar panel. One application is to put the cells on windows where they can temper the light while powering a building. The dots disappear when you take a few steps back from the window, in fact many commercial buildings have dots painted on the exterior glazing to control glare.

So far so good. We have windows that make power for our building. The “killer app” is to add a layer of organic LEDs or OLEDs to the windows. The OLED / Sphelar Solar matrix can be on a single lite of glass. The whole window can thus become a light absorbing and light emitting source. OLEDs are very efficient and they can be any color, display patterns or show moving images.

Please note this Solar/OLED is not on the market and as far as we know no-one is actively developing it.

This technology, if ever developed, could lead to buildings that change their appearance or it could lead to Times Square on steroids…..Hmmmm


Sunday, February 25, 2007

GE Announces Efficient Bulb (sort of)

Here at Sustainable Design Update Central Command (S-Duck), debate has been hot and heavy over GE's announcement of a High Efficiency Incandescent or HEI lamp. What GE announced with much fanfare is a light bulb that won't be on the market for several years, a light bulb that will be about half as efficient as a current generation compact fluorescent (CFL) lights.

While we applaud GE for working to reduce energy consumption, we are concerned that the effect of announcing a product that won't be available for several years is to reduce interest in the much more efficient compact fluorescent lights and LEDs. Many consumers will think “why should I change to those funny compact fluorescents when regular old bulbs will be just as good. The effect of GE announcing their HEI bulbs so many years ahead of production is to cut interest in CFLs.

GE proposes to introduce a High Efficiency Incandescent bulb “Over the next several years that will achieve 30 lumens per watt [1]. While this is a great improvement over the terrible performance of the current GE bulbs, it is only half as efficient as a current CFL. Moreover it is only one quarter as efficient as some LED lights.

The Numbers:

Maximum possible luminous efficiency is 683 lumens per watt but this is for a yellowish green light, the color our eyes are most sensitive to. Considering we prefer white light a more realistically achievable efficiency is 242.5 lumens per watt for white light.
Now lets look at GE's proposed HEI bulb.

It achieves 30 L/W / 242.5 (Maximum Possible) = 12.4 % efficient

This is for producing white light. The GE High Efficiency bulb is only 5% efficient at converting electricity to light. The rest of the energy consumed by the GE bulbs is converted to heat.

GE states that they have an ultimate goal of achieving about the same efficiency as the current generation of CFLs but by that time CFLs will have improved and LED lights will very likely have taken the market.

[1] Lumens per watt is like miles per gallon. The bigger the number the better.