LEDs are used more and more as incandescent light replacements. There are at least 4 possible advantages to using LEDs compared to incandescent sources: a) longer lifetime, i.e., years rather than months of service, b) power savings in some applications (more on this later), c) reduced heat output in some applications, and d) deep saturated hue (color) of output without filters. Does this mean that LEDs are generally more efficient, that is, can they be used to save power? With the current state of the art, incandescent bulbs actually put our more visible light per watt than most LEDs. So, if you want white light or if you don't care about color of illumination, incandescents are somewhat more efficient than any combination of LEDs, and they remain more efficient than the newest 'white LEDs'. However, if you want single color illumination, LEDs can be much more efficient, since, in that case, much of the light output of the incandescent source is absorbed by a filtering system. If we include fluorescent fixtures, here is the general picture of light source efficiency: 1) As of today, fluorescent fixtures remain the clear winner in terms of output in lumens/watt. Halogen incandescents are second. LEDs are third. 2) LEDs win the race if what you want is light of a single color available from efficient LEDs. The losses involved in filtering fluorescents and incandescents are such that LEDs win out here. Examples include stoplights and auto taillights. 3) LEDs provide the longest lifetime by far. 4) If your supply is some low DC voltage, driving circuits for LEDs are extremely simple and cheap compared to same for fluorescents. 5) White LEDs, although they do not presently provide as many lumens/watt as incandescent bulbs, can be useful because of the long life and low heat output. For reference, fluorescent fixtures put out about 30 lumens per watt. Incandescent bulbs put out about 8 lumens per watt. In summary, if I were equipping a remote cabin with lighting, I'd be using low voltage fluorescent fixtures at this point in time.