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Don't get too excited...
Firstly let me say that i am a keen advocate of LED lighting - my house
is fully converted to LED.
My other hobby is Scuba diving - and am an electronic engineer by profession.
I have been building my own dive lights for me and others for the better part of the last decade. underwater dive lights (apart from the need to be waterproof!) need to be as light and as efficient as possible.
Incandescent dive lights have gone the way of the dodo and HID are quite bulky for the light output (albeit probably the best suited type of light for u/w)
LED are cheaper and easier to build, and the most efficient
way of producing bulk light underwater.
The posted article is interesting, but stretches the truth somewhat.
Firstly - mercury vapour lamps produce about 50 LM/W (not 30 as stated in the article)
Secondly - the maximum theoretical output from LED is around 300 LM/W
(current technology gives us about 125 in commercially available units)
hard to see how we will get to the 400 LM/W stated in the article.
The major challenge with LED is keeping them cool -
they don't like going over 50C - if they do for any long period they
will destroy themselves pretty quickly.
That is why most commercial units at the moment are quite low powered - they have to be to keep the heat and associated temps below the self-destruct point. Aussie streetlamps have to sit outside all day
every day - i'm sure our sun can easily bake LED's to more than 50C.
Lumen efficiency is one side to the story -
mercury vapour happens to work very well because our eyes are very sensitive to the light frequencies they output - so we dont need large wattage lamps to light up a highway.
Apart from some stretches of freeway - most of the lamps round here in sydney are either xenon HID or fluorescent - which have around the same
efficiency as LED, if not the lifespan.
Where LED has a clear advantage - is the fact that they can be turned on and off quickly and often.
(mercury vapour or HID takes a few minutes to come up, and needs to cool before being re-started)
The idea of the highway lights only coming on when they sense a car coming is where a lot of savings can be made....
also having solar charged batteries poer pole instead of having to string up thousands of k's of copper....
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