While LED lighting is still far from the mainstream, early solid-state lighting products are starting to appear on the market in a variety of form factors and designs. At this stage, it's too early to envisage how LEDs will develop, and what features and applications will prove attractive to consumers, over the coming years. Let's take a look at the current state of play.
The 48-inch LED T8-sized tube light is an interesting example. While it is not intended as a drop-in replacement for the traditional fluorescent tube, which needs a fixture with a ballast unit, the product is targeted at fluorescent tube light markets.
Each 18-watt tube comprises three rows of 96 LEDs; the outer two are cool-white, while the inner one is a warmer yellowish-white. The power supply runs distributed down along the back of the two LED PCBs that are stapled together to achieve the correct length. The tube emits 820 lumens, or approximately 46 lumens per watt, which is roughly half the 100 lumens per watt obtainable with the equivalent high-quality T8 fluorescent tubes.
The tube's life is claimed to be 50,000 hours, which seems reasonable for the LEDs, but a little optimistic for the assembly as a whole, given the large number of electrolytic capacitors used must be de-rated for use in higher temperature environments. The 288 LEDs are arranged in 18 parallel strings, each containing 16 diodes.
Since fluorescent tubes sell for around $2, and have a more than adequate quality of light, the real challenge is the T8's sticker price, which is 30 times more. The high price of LED products can only be justified when the overall replacement cost of alternatives, taking into account labor, downtime, and access difficulty, is greater. But for the majority of applications, this is not the case.
Right now, the LED lamp market is still in its infancy, and demand is uncertain, both due to high prices and an unclear product road map. Lacking is credible top-level direction; governments are pursuing a variety of ad hoc energy policies, most of which don't address the fundamental issue. That is, that most countries do not have enough generating capacity; either demand has to be cut, or the world must build several more power stations close to cities.
To top it off, there are undetermined variables, such as what the price of energy will be, and whether governments will collectively embrace a truly green internationally-agreed energy agenda (and stick with it). Clearly, global energy needs and policies will affect investment in energy-efficient hardware. But the only sensible, sustainable long-term strategy is to cut back on demand.