1 Compact Fluorescent Light Bulb = 1 Nuclear Power Plant
I'm a big fan of compact fluorescent light bulbs; they use a fifth of the energy of an incandescent bulb yet produce the same amount of light. The resulting reduction in your electric bill can be substantial, particularly if you live in a state like California where electricity is relatively expensive.
I've seen several articles recently that highlight how significant the energy savings could be if every home in America switched to compact fluorescent bulbs.
A CFL in every Home = 1 Nuclear Power Plant
There are an estimated 110M households in the US, so if you replaced one 60W incandescent with a similarly lumen-rated 13W CFL (I'd estimate a distribution cost of $100M-200M), you'd save just over $4.1B in electrical bills over the lifetime of the bulbs ($0.10/kWh over 8000 hours). At 5 hours/evening of usage (~4.4yr), we're looking at almost a billion bucks a year. That's not a bad ROI.
A global switch to efficient lighting systems would trim the world's electricity bill by one-tenth:
The carbon dioxide emissions saved by such a switch would, dwarf cuts so far achieved by adopting wind and solar power.
"Lighting is a major source of electricity consumption," said Paul Waide, a senior policy analyst with the IEA and one of the report's authors.
"Nineteen percent of global electricity generation is taken for lighting - that's more than is produced by hydro or nuclear stations, and about the same that's produced from natural gas," he told the BBC News website.
The carbon dioxide produced by generating all of this electricity amounts to 70% of global emissions from passenger vehicles, and is three times more than emissions from aviation, the IEA says.
Replacing all the incandescent bulbs in your house with fluorescents might equate to the carbon dioxide savings in driving a hybrid automobile:
We can estimate the annual greenhouse gas savings from a Prius vs a Toyota Matrix, FWD, automatic. The Prius gets an EPA-rated 55 mpg, vs 31 mpg for the Matrix. Assuming 12,000 miles annually, it will save 169 gallons of gasoline per year. Since each gallon produces 11.1 kg of CO2-equivalent GHG emissions, the Prius saves 1,875 kg of CO2-equivalent annually.
I would guess each bulb can save you about 85W (100W-15W), so 15 will save you 1275W. If the lights are on 2400 h/yr (6.6h/day), they will save 3,060 kWh. Using a national average of 1.35 pounds of CO2 per kWh, this will save 4131 lb or 1,875 kg of CO2. So it doesn't seem like an unreasonable statement that the two are comparable.
CFLs aren't cheap, though. I've found the best inexpensive sources for CFL bulbs of various types are Costco and IKEA.
For example, we leave the kitchen lights on almost continuously when we're at home; that's five 60 watt bulbs. Replacing those with 14 watt equivalent compact flourescent bulbs equates to a 230 watt savings. That alone is enough to feel the difference on our monthly electric bill!