Lightbulb Math in 2016

I ran across this 2015 article on LED light bulbs in my Twitter feed today, and it reminded me of a short post I made… over 10 years ago now running some numbers on power savings from replacing 60W incandescent bulbs with 13W CFLs. I figure it might be worth running the numbers for 2016.

  • Home Depot sells a 4-pack of 60W Equivalent LED bulbs for $7.97 ($1.99/bulb). These are 2700K soft white, 8.5W, 800 lumens bulbs and are rated for 10,000 hours
  • Note, this is actually cheaper (and brighter) than the cheapest reasonable 60 Watt Incandescent A19s I could find. These are 2700K soft white, 60W, 630 lumens bulbs rated for 3500 hours (pretty good!) and cost $4.97 for a 2-pack ($2.49/bulb).
  • Philips also sells a 60 Watt Equivalent Halogen A19 4-Pack for $6.97 ($1.74/bulb). This is 2720K soft white, 43W, 615 lumens, rated for 1900 hours.
  • The EIA publishes detailed average electricity pricing – the national average is about 13 cents/kWh. Prices vary widely (as low as 9.5 cents in WA and LA and up to 27.8 cents in HI). The cheapest residential electricity rate I could find is in Chelan County, at 2.7c/kWh. They also provide Gbps Fiber. (This wouldn’t be a bad place to set up a mining farm.)
  • Before we calculate the power-inclusive cost, lets just total bulb replacement cost based on rated lifespan. The LED bulb is $1.99/10K hours, the incandescent is $7.10/10K hours, and the halogen is $9.17/10K hours. It’s somewhat surprising, that even if electricity were free/infinite and a non-issue, the LED bulb would still be over 3X cheaper than the incandescent now (post 2014 phaseout, prices will probably keep going up if you can even find standard incandescents).
  • Now, lets look at power over the same 10K hours using the 13 c/kWh average rate. The LED light bulb would use 85kWh, costing $11.05. The incandescent would use 600kWh, costing $78. And the halogen would use 430kWh, costing $55.90
  • In my 2006 post, my 110M household number stats was actually probably outdated/from previous years. In any case, Statista pegs 2015’s households at 124.59M, we can conservatively ballpark 2016 household numbers at 125M
  • We can now do a 1:1 update of the 2006 numbers. Replacing a single incandescent light-bulb per household with an LED bulb (probably a lot less common now), you would save approximately $9B over the lifetime of a single LED bulb
  • When looking at the power usage, say taking the 5 hours/evening usage from the old post (1826.25 hours/year), we end up at just under 12M MWh power savings, or about 1.5 1000MW nuclear power plants
  • Based on a ballpark distribution cost of $250M (assuming bulb+handing out bulbs = retail cost of the bulb), we end up at about $21/MWh saved, far cheaper than USD/MWh costs for any type of new power plant.

Misc notes:

  • Incandescents are almost impossible to find these days, besides as specialty/decorative versions. These vintage quad loop ones are pretty neat.
  • The LED bulbs linked above are CRI80 while the incandescents/halogens are CRI100. A high CRI (90, 93) LED bulb runs at about $4 or $5. Either way, they should in general be more pleasant than most CFLs from last decade.
  • GWB signed the EISA that had a low-efficiency incandescent phase-out (triggering the introduction of halogen alternatives, more about that here and on wikipedia)
  • Chelan County actually looks quite pretty
  • I think I had the savings cost off on my original post (fixed now I hope). Math! ¯\_(ツ)_/¯