Striaght Dope on efficiency of light sources

Googling, I find a lot of contradictory information about the
efficiency of light sources, usually measured in lumens per watt.
(Note: I am not interested in directionality, which some people
figure in so as to boost the reported efficiency of whatever they
are selling. I only care about visible photons out divided by
watts of electricity in, weighted and adjusted acording to the
response of the human eye.)

I see an ultra-bright white LED panel claiming 28,000 lumen output
and 1.4kW energy consumption. Not too bad, depending on which
numbers you believe about other light sources.

Websites critical of halogen bulbs claim that their best case
efficiency is in the high teens of lumens per watt, while sites
selling them claim efficiencies as high as 97 lumens per watt.
The site claiming 125 lumens per watt for halogens was dedicated
to indoor marijuana agriculture; I won't bother asking what they
were smoking when they made that claim.

One site gives an efficiency of 30 lumens per watt for fluorescents,
with a date of 1930; I assume that number was correct back then,
but that modern ones are better. Another site says that fluorescents
can produce up to 100 lumens per watt, but doesn't give specifics.

Another site claims that the best white LEDs give 37 lumens per
watt, that 60 lumen/watt LEDs (not necessarily white) will be
shipped in 2005, and that a 100 lumen per watt prototype LED has
been demonstrated.

If I interpret the halogen data skeptically and believe everything
claimed about LEDs, it would sound like LEDs beat halogens and are
about to become competitive (output-wise) with fluorescents. How
does this compare with reality?

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Relevant Pages

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