What type of light gives the most lumens/watt?

[BatteryCharger]

Just wondering, which type of light gives the most lumens per watt? HID? Flourescent? LED?

[Mark2]

IIRC it's fluorescent, HID, LED, incandescent.

[yuandrew]

Low Pressure Sodium

and

Microwave Sulfur (I don't think they're still researching this though)

[jtr1962]

Here are some of the typical ranges that I remember for each type:

low-pressure sodium: 125 to 200 lm/W (typical 150 lm/W)

high-pressure sodium: 80 to 125 lm/W

HID: 65 to 110 lm/W

T-12 fluorescent: up to 90 lm/W (typical 60 to 80 lm/W)
T-8 fluorescent: up to 100 lm/W (typical 85 to 92 lm/W)
T-5 fluorescent: up to 104 lm/W (typical 95 to 100 lm/W)
CFL: 60 to 70 lm/W typical (includes ballast losses)

mercury vapor: 55 lm/W

xenon arc: 30 lm/W

incandescent: 15 lm/W typical (as low as 1 lm/W for small lamps, up to 40 lm/W for short-life bulbs)

white LED: 15 to 30 lm/W typical, up to 60 lm/W next year (current record 74 lm/W)

colored LED: 5 to 55 lm/W depending upon color (current record is 102 lm/W @ 618 nm)

For large amounts of white light HID in the larger sizes (400W to 1000W) is currently the most efficient. For residential and office use T-5 fluorescent is the most efficient option although T-8 comes fairly close. For small uses LED is generally more efficient than incandescent. For colored light LED is the best choice regardless of size.

[mattheww50]

Unless you happen to want yellow light, in which ase a Low Pressure Sodium (SOX) lamp wins hands down. Even a small 18 watt SOX is good for 100 lumens/watt.

[Zelandeth]

Best answer to this I think is the chart at the bottom of this page at Lamptech.

http://www.lamptech.co.uk/Documents/...troduction.htm