LED-lighting – from twinkling star to supernova in the years to come.

Will half of the worlds lighting 20 years from now be from solid state LED (Light Emitting Diodes)? From a device that some years ago was used only to indicate that electronics was in stand-by? If so, this source have to improve its performance in lumens per watt by a factor 5 (to 150 lumens per watt), but would then be able to reduce installed power  with 120 GW and saving 350 Mtonnes of Carbon-dioxide each year, according to the MIT Technology Review.

It may sound as science fiction or wishful thinking and to understand the opportunities we will have to look beyond the simple energy issues and into the other properties of LED-lighting such as size, configuration, life-time, colour rendering, etc. When talking about energy efficiency, we are basically trained to think in terms of replacement. We have seen how Compact Fluorescent Lamps (CFL) has gained a certain market share by just replacing incandescent light bulbs only with difficulty and over a fairly long time period. LED may also be used as replacement but its properties may be of such a nature that the entire concept of lighting could change. But let us begin with the energy part.

One comparison presented at the Right Light conference in Shanghai 2005 states that CFLs today has a performance rate of 60 lumen per watt and deliver light at a cost per lumen of 1 cent. The same author predicts that white light from white LED may be above 60 lumen per watt  the year 2010 (presently at 30 lm/w and costs 35 cents per lm), but at a lower cost per lumen than from today’s CFL! This seems to be a conservative estimation considering that US DOE predicts 150 lumen per watt the year 2012 in their road-map for LED-lighting.

Reducing cost from 35 cent per lumen to 1 cent seem rather drastic looking from a learning curve perspective but we may have to remember that LEDs will be produced in huge amounts not only for lighting and that there will be breakthroughs in the electronics, i.e. how the photons are produced and directed in the LEDs.

Another breakthrough will happen to the lifetime that would be more than 100 000 hours for an LED 2010, i.e. 100 times the life time of an incandescent bulb and more than 10 times than that of a CFL.

And it is here we start to see that LED-lighting might be revolutionary. They are (among other things) small, have a long life-time (and thus less frequently need to be changed), operates at low-voltage, are hard to break, has no mercury content, offer several choices of colour etc. etc. They are in short a dream both for a lighting designer and for the maintenance staff. Consequently the US Department of Energy in their estimations assume that the commercial sector will be the market that pulls LED-lighting in the time-span 2010-2025 with a market share of some 70%.

But if LEDs has the capacity to drastically change the lighting in the commercial areas of the affluent world it may do even more so in the developing countries. In so many countries lighting today is fuel-based. In some cases because people do not have access to the grid and in some other because of tradition. In any of these cases the fuel lighting is a bad alternative being expensive, polluting and providing lousy lighting. With LED a brilliant alternative arises since the energy-consumption is low and since it can be supplied by Photovoltaics. So LED can open up for poor people to study and work with better light and cheaper!

From small steps to long strides.

At the Right Light conference was also an example of how LED may be adapted into the type of lighting we are used to, with success. LED seems then not only able to work in the replacement market, where e.g. CFL has failed, but also have such properties that enable it to capture entirely new fields. As always, the biggest barrier will be in our own minds to embrace the change, but if we think about how we listened to recorded music in the past and how we are doing it today we easily understand that the small steps can take us a long way.

So all things considered, the solid state lighting with LED,  may very quickly turn from a twinkling star to a supernova that have all the goodies we ask from new technology  in terms of cost, environment and social benefits.