Thursday, March 10, 2011

Two Discoveries in LED Lighting

Why can’t LEDs be made with the same lithographic techniques that produce microprocessors? It turns out the stumbling block isn’t the lithography, but the substrate. Microprocessors are built on silicon, a material that engineers have long since learned how to produce on a large scale. LEDs typically are made by putting gallium nitride on a base of sapphire or silicon carbide, materials are much harder to produce consistently. To work around this, LEDs are manufactured almost one at a time. But that may be changing in 2013. Bridgelux, an engineering company working on LED manufacturing technology, says it has a way to grow gallium nitride on 8-inch silicon wafers, nearly the same kind that are used to manufacture microprocessors. With this invention, it should be possible to manufacture LEDs at microprocessor factories, on the same equipment. This means LEDs can be made hundreds at a time, like microprocessors, resulting in lower manufacturing costs.

Bridgelux says the energy efficiency of its new LEDs is about the same as that of current LED room lighting, and it hopes to make incremental improvements over the nest two years to keep up with the industry as it brings its first products to market. That will be a race against time, as dozens of other companies are creating their own advances in LED manufacturing, resulting in prices that fall every year.

It is a safe bet that at least a few of the LED breakthroughs we’ve been reading about will, probably in 2012 rather than 2013, bring us LED room lighting at prices similar to those those of current compact fluorescent lighting, but with 3 times the energy efficiency and a choice of colors. When that happens, or perhaps sooner, LED will become the dominant room lighting technology, and we’ll finally be able to retire fluorescent lighting.

LED lighting may be coming sooner than that, as soon as this summer, to a supermarket or restaurant near you. Why? Besides the long-term cost savings of LED lighting, researchers have found that LED lights make food look better. Consumers even say food tastes better when they eat it under LED lights, when compared to the greenish fluorescent lighting currently used in almost all commercial buildings. In a restaurant, it’s an investment of about $15 per table at current prices to replace fluorescent table lights with LEDs. It’s an investment that pays for itself in less than 5 years with reduced electric use anyway. If it also provides customers with a better experience of the food, and a small fraction of customers spend more as a result, the improved lighting could pay for itself in a matter of a month or two, so I don’t think restaurants that can spare the cash will delay too long in making the upgrade.