Get rid of your incandescent light bulbs to save the environment and the world! Right?
Depends.
Lighting technology has advanced enough (decades ago) that electricity consumption can go be cut to 1/3, 1/4, or even less of the "original" amount. I'm speaking, of course, of the switch from incandescent bulbs to compact fluorescent light bulbs (CFL) -- or just fluorescent, in general. For example, an equivalent CFL that produces roughly the same amount of visible light as a 40 watt incandescent consumes only 7 to 10 watts; a 60 W incandescent is about 15 W for a CFL, and 100W is about 20W.
I remember seeing CFLs around when I was a kid in the 1990s. They were new tech then, and they were pretty expensive. Over the past decade or two, they've become more widely adopted and promoted by utilities or government agencies for being "energy efficient". That's not entirely accurate though.
Okay, to get it out of the way, CFLs contain mercury, which is a very toxic heavy metal. And as we all know, shit happens. You break them, and you suddenly have a huge toxic hazard according to experts and safety-minded people. The usual drill after breaking one is to open all the windows and air the room out to get rid of the mercury vapour (or dilute it). Sweeping and soaking the toxic mess also requires care. Good luck with carpet. As far as I know, incandescents were a simple sweep job when they broke. That's out of the way...
Going back to the energy issue. CFLs consume less electricity, that is true, but do they consume less energy? As a single, individual, isolated unit, yes, CFLs consume less energy. However, as you grow up, you are taught (and learn, yourself) that everything is interconnected. This is also the case for light bulbs. Incandescents "sucked" because a lot of energy that they consumed was converted into heat energy -- wasted, one could say. On the other hand, CFLs are much more efficient at producing light energy, though they do still get hot.
What does this mean for overall energy efficiency?
Location, location, location...
Your energy consumption is influenced by a number of things. The big one, though, is location. Your location affects your climate: the temperatures you experience, the amount of sun you get, the amount of heating you have to do, and the amount of cooling. Location also influences which country you are located in and all the political, social, geographical, and environmental baggage that comes with each one. The only thing you really need to care about is where and what your power comes from.
For example, you may live in a state or province where the majority of your power comes from clean and "environmentally friendly" (ignore the forests and land, just worry about the emissions) hydro-electric power. If you want, you could throw nuclear power into the same "clean" category as hydro-electric. Alternatively, your area's power production could be from "clean" dirty, dirty coal or "cleaner" natural gas.
Thinking of the whole, let's start to put two and two together. Switching to energy efficient light bulbs saves electricity. Theoretically, that means the "clean" or "dirty" power plants don't have to run as hard. If they don't have to run as hard, then fewer emissions, carbon dioxide, sulphur, nuclear waste, etc. are created and disposed of in the environment. And this is partly out of my ass, but once upon a time, I remember hearing that around 20% of all electricity consumed goes to lighting. Saving the planet, one bulb at a time? Or are you still keeping your thermostat nice and toasty in the winter, and nice and cold as a witches teet in the summer?
I'm going to guess that you didn't change your thermostat settings after you switched your bulbs out. Remember all that energy you saved in the form of electricity? Ya, that stuff was heating your house up.
Incandescent or CFL: The Economic Perspesctive
In a location that is heating-dominated, meaning that you spend most of your energy and money keeping your building warm, you have to make up the lost energy somehow. In a cooling-dominated location, you actually aren't doing that poorly.
Starting with cold locations, if you switched from a 40 W incandescent to a 10 W CFL, you have now lost 30 W of energy that was "wasted" inside your home as heat. All else being equal, you would have to make that up by burning more fuel in the form of natural gas, propane, or heating oil. Thanks to the fracking and natural gas boom, your wallet might not hurt too bad if you were on natural gas. Unfortunately, you would be hit a bit harder if you were using heating oil. From an economic perspective, the choice between incandescent or CFL bulbs would depend on whether the cost of electricity or heating fuel were more expensive, watt for watt of energy.
In a warm location like in the southern states, you would be running your air conditioning for most of the year. Using bulbs that put out less heat would then be ideal because every watt that you add to your home as heat is a watt that your A/C has to get rid of. Your A/C uses electricity usually, so you'd be compounding your problem.
FYI: Thermodynamics-wise, every watt of electricity consumed should break down into the most stable form of energy, which should be heat or thermal energy. That should mean that your visible light becomes heat too (i.e. you get heat from every watt the bulb burns). You should be able to google an energy density (in watts) per cubic meter or cubic foot of gas, or per liter or gallon of liquid fuel.
Incandescent or CFL: The "Environmental" Perspective
So you decided that you should go one way or the other based on cost. Okay. You could (and probably will) do that. But do you care about your environment, global warming, carbon emissions, and the greenhouse effect?
I'm going to guess, "no". In case you do though, here are some other things to consider!
Putting economics aside, your power comes from somewhere as previously stated. What it comes from should impact your decision. For example, if you were in a cold, heat dominated climate and most of your energy came from hydro-electric power, you'd be better off sticking to electricity. The reason is that hydro-electric power is "clean" in that you don't have to to burn anything. Otherwise, you'd have to burn more fuel to heat your home. In a hot climate with mostly A/C running, then saving electricity works out any which way -- you'd save money and require less power to be produced.
Life is Grey
Hard rules set in stone. Perfect. Right?
Like how everything in life is interconnected, everything in life is more complicated than it looks. I defined many forms of "clean" energy, but are they really?
Hydro-electric doesn't produce emissions except for the massive scar caused by pillaging the natural environment, regular consumables, vehicles, etc. Nuclear is great except for the massive energy and material cost of building the plant, and the toxic radioactive fueld and waste it consumes regularly. "Clean" coal still burns coal except it filters the smoke and waste better -- not to mention the cost of acquiring the fuel source. Natural gas is similar to coal except cleaner burning by nature.
What to do... What to do... There are professionals who actually spend their time breaking everything down to their carbon cost throughout their life-cycle. Luckily (yep, lucky), I'm not one of them. Do what feels right, or ask someone who knows better!
LED Bulbs
Everything I stated should be true for LEDs and CFLs. That is, you could use CFL and LED interchangeably. The only differences would be that LEDs should last longer and if/when they break, they shouldn't turn your home into a toxic soup. I have yet to own a "standard" LED light bulb yet since they are very expensive, but the time is coming. IKEA made an announcement a while ago that they would stop selling CFLs within the next few years and switch over to LEDs completely. In fact, IKEA actually has a full line of LED bulbs for sale at reasonable prices as of writing this in early 2013.
