> my inner geek [firstname.lastname@example.org] wrote:
> >Good news, Philips just announced a light bulb
> >that lasts for 2 years. Oh joy. Maybe in 2015 they'll spill the
> >beans on their 1968 patented lightbulb that lasts 200 years.
> Well, given that patents only last about 20 years, why don't you go out, get
> a copy of the patent, and start selling 200-year lightbulbs? Or is this just
> another of those mythical patents that the evil corporations bought up so
> no-one could use them?
There are already lightbulbs that are warrantied for 80 years. They use arrays of white LEDs. These are pretty energy efficient as well. The reason why they aren't more widely used is partly because they cost $30 each or more, and for most all such devices, because they are depreciated almost completely within 3 years, and most facilities are remodeled every 15-25 years, lighting fixtures typically get junked in the process and replaced with new ones. Another factor to consider is that internal discount rates depreciate the value of savings that far into the future. The savings you earn in the first 2 years account for over half of the discounted savings, while the savings in the first 5 years account for 80% or more, etc. Anything beyond 10 years is a waste of money, given todays growth rates. I beleive that long life devices like this are only worthwhile when the long term growth rate is below 1%.