
Performance per cost is going up but not rapidly enough to meet our polar shift 
needs. 

See page 8, 9, and 10 of a Nov. 2001 report.
http://lumileds.com/pdfs/techpaperspres/MRS2001.pdf

See page 5, 11 in the following this years report
http://www.lumileds.com/pdfs/techpaperspres/SID-BA-Paolini.pdf

See page 2, in the following this May 02 report.
http://www.lumileds.com/pdfs/techpaperspres/OIDA_28May2002.pdf

Note that current red LED's are similar in efficiency to Fluorescent lights at 
around 70 to 110 lumens/watt. White LED's fall down to 20-30 Lumens/watt and are 
equal to or slightly better than Halogen but not as good a Mercury Vapor.   If 
one studies the rate of change of efficiency (doubles about every 5 years) and 
the cost (decreases by 10 x over the next 5 years).   What this says is that in 
about 5 years the 1000 watt priced out in my example at $6000.00 will be down to 
about $300.    I wish we could postpone the polar shift for 5 to 10 years until 
we can afford to pay for LED lighting. J

The reality is with less than 5 months to go we need to buy our lighting needs 
now or in the next few months.  If one can't find the low price LED's on the 
market now then in 5 months it is predictable there will be not much change. 

One good thing about these charts is that it shows the most efficient current 
lighting to be High pressure sodium (160 lumens/watt) then Fluorescent and Red 
LED at about (80 lumens/watt) then Mercury Vapor (60 lumens/watt), then Halogen 
(25 lumens/watt, and finally Tungsten (14 lumens/watt).

The real advantage to us of LED lighting is unbreakable, long lasting, and works 
well with DC power.  Efficiency at this point of time is not a big enough 
factor.  Although unlike filament bulbs at lower voltage  LED become more 
efficient instead of less.  For these reasons LED's work well for task lighting, 
however because of cost are relay not a match when a lot of light is needed. 

So the bottom line is if you can afford LED's go for it, if you can't then 
consider using Sodium or Florescent or a combination of both.   These have the 
disadvantage of needing AC power.  As a last resort one could always use 
Halogen, which will run on DC directly. 

For other papers on the subject see:
http://www.lumileds.com/pdfs/techpaperspres/

