Now that the manufacture of 100W incandescent light bulbs has been banned in the US, with 75W, 60W, and 40W bulbs to follow, we must look at the history of the allegedly “better for the environment” replacements, primarily compact fluorescent lights (CFL) and LED lighting.
The scorecard for CFLs isn't all that great, with far too many of them failing to live up to the hype, specifically in regards to their service life. Claims of 10,000 hours have been made, but too many of them have shown to have far less than that, sometimes no better than the incandescent bulbs they're supposed to replace. That wouldn't be so bad if they didn't cost many times that of an equivalent the old fashioned Edison bulbs. Disposal is also an issue because the contain mercury, meaning you aren't supposed to throw dead CFLs into the trash. They have to be disposed of as hazardous waste. (Our town has an annual hazardous waste disposal day. Town residents can bring all kinds of waste that can't be thrown into the trash, like cleaning chemicals, unused pesticides, and of course fluorescent lights which include the older tube-style lamps and CFLs.
CFLs do use less electricity for the amount of light they produce as compared to incandescents, but the less than stellar service life for some CFLs doesn't justify the cost. (The extra money you pay for them is never returned in regards to the lower cost to run them.) Another issue with CFLs is that they don't reach full brightness for a minute or two after they are turned on. That's not exactly convenient.
LED lights are still in their infancy, but are getting better all the time. Claimed service life is 50,000 hours, but there have been too many of them that fail well before their time, in some cases only hours after being installed.
It isn't the LEDs in the lights that fail. In most cases the LEDs that make up the lights work just fine when the correct current is applied to them even after the lamp stops working. Instead, much like CFLs, the problem is in the power supply circuits that take the house current and convert it to a voltage and current that are required for the LEDs to operate properly. In some cases the power supplies were poorly designed and built (usually the case with cheap Chinese made LED bulbs). The most common failure mode for these supplies is poor solder joints on the components in the supply. As the article linked above explains, failed LED bulbs start working again after the bad solder joints are resoldered. It's a workmanship issue. Not all LED manufacturers have this problem. Probably one of the better made LED bulbs out there now is manufactured by Philips. They have minimized the number of solder joints and where wire would normally attach to the supply to connect the house AC or the LEDs, Philips uses connectors which greatly reduces this problem.
A second power supply issue is the use of components that aren't rated for the conditions they'll under which they'll be operating. So after operating for some period of time, they fail which turns your expensive LED lamp into nothing more than an ornament. (A more detailed and technical explanation about this topic an be found here.)
Another downside to LED lamps – their price. They cost a lot, with a (good) 60 watt equivalent priced at about $25. It would take a long time to recoup the cost of the bulbs from the savings achieved by reduced electricity usage.
And another downside to LEDs to consider is that as LEDs age with usage, the amount of light they produce decreases. For most people this won't be an issue. But for others it may cause problems.
Am I advocating the continued use of incandescent light bulbs and abandoning the use of other lighting technologies? No. But I am saying is that we should be aware of the advantages and disadvantages of each type of lighting before deciding whether or not to make the switch.