Updated May 6
Let's hear it for Coal ;-)
"Coal is cheapest way to power a light bulb":
An article basically comparing the cost of using coal, oil or gas sources, itself referring to a longer column analysis about powering light bulbs with such sources.
Coal is also cheap compared to renewable/nuclear energy sources
(as can be seen on any online discussion, there are numerous arguments,
including the unfair cost comparison of existing coal plants versus new plants
of other types, and the cost of dealing with environmental effects, but a simple pointer is that otherwise alternative sources would not have to be mandated on a free market).
In any case, while not directly related to light bulb regulations,
it throws up an interesting angle about electricity usage cost for consumers,
and how the energy source used is much more important in that regard than what light bulb you choose to use... as also covered on the Ceolas.net website accompanying this blog.
Image from a "Good.is" site (without further information).
Click on image to see the bigger original version...
(and click on that in turn to enlarge it):
A further important point, related to coal compared to most other sources,
is how effectively the same amount of coal is burned, regardless of whether your light bulb is on or off at night, and consequently also regardless of what bulb you are using.
This is not just because the switchover savings are marginal, as covered and referenced on the Deception page, but because slow base loading coal power plants, calibrated to higher day usage, can hardly be turned down at night.