Already there are several questions:
- How can a blue bulb get us white light?
- What makes LED bulbs so efficient in the first place?
- What about CFL bulbs?
- Why are you posting this on a library blog in the first place?
First, a blue bulb will not give us white light. It will give us blue light. The reason we need it is that in order to make white light you need to mix the three primary colors: Red, Green, and Blue. Red and Green LED's have existed for a while now, but the blue ones have always been too difficult or expensive to manufacture. Which brings us to the second question...
LED stands for light emitting diode, and they are everywhere. Pretty much every little indicator light you see on an electronic device is an LED. These are the same LED's that are used (by the millions) in LED screens. They have two major advantages over conventional lightbulbs: They last far longer and they generate almost no heat at all.
Incandescent bulbs are hot. Really hot. Basically an incandescent bulb works on the same principal as the heating element from an electric stove: Let's heat this thing with electricity until it gets so hot it glows. Less than half of the energy put into an incandescent bulb is released as light, the rest is heat. This is a big waste, unless you're planning on using light bulbs to heat your house (good luck sleeping in a room full of 75 watt bulbs). LED's release (almost) only light, enabling us to get the same amount of light for far less electricity. CFL bulbs, while more efficient than incandescents are not as good as CFL's and still generate a lot of heat. Also they are full of mercury and phosphorus, two profoundly unhealthy elements. If you read the fine print on the package, they strongly suggest you to leave the room for at least an hour if you break one.
Now that the first three are covered, now for the important one: What does this have to do with the library? A few things, actually. As the repository for ALL KNOWLEDGE, pretty much any subject is fair game for a library blog. Furthermore, given that many WHS library users are here for the computers, devices that would not exist without LED's. And lastly, do you think these guys just woke up one morning and said "Hey, I think I'll make a blue LED today"? No. They said "Hey, I think I'll research semiconductors and crystal growth. Again. Just like yesterday, and the day before, and the day before. In fact, I can't remember a day in the past year when I haven't done research." Okay, so they probably didn't say exactly that and whatever they did say was in Japanese, but you get my point: Nearly every great scientific development ever has required hours and hours of research, a process which libraries and librarians are famed for supporting.