Poor Design Workshop: SolarWorld
Welcome to another edition of Poor Design Workshop!
I saw this poster in the BART yesterday.
It’s kind of a nice poster… until you actually read it.
It’s time to put the sun to work
Power from the sun
400 000 000 000 000 000 000
kilowatts per second
America’s largest solar manufacturer since 1975
First, “kilowatts per second” is a non sequitur here. (reference) Though granted there is often confusion about terms like this. Try to think of it this way: kilowatts is a rate, like “miles per hour”. You don’t say “He was driving at 55 miles per hour per second“… because, well, that’s stupid. Similarly, a 60 watt light bulb uses 60 watts, not 60 watts per second. With electricity, 1 Watt is equal to 1 Joule per second.It’s kind of OK for a layman to make this mistake, but not so much for America’s largest solar manufacturer since 1975.
Ok, let’s just sweep the “per second” thing under the rug and look at that big number with all the pretty zeros. “400,000,000,000,000,000,000 kilowatts” = 4.0 x 1023 watts. Let’s assume they meant to say that the earth is being hit by 4.0 x 1023 watts of energy from the sun. The trouble is, if that were true, our planet would boil off into the vast nothingness of space in minutes. In actuality, the earth catches 1.8 x 1017 watts (reference) from the sun. Their number is off by 6 orders of magnitude… a million times!!!
Ok, maybe that big number isn’t supposed to represent how much power that hits the earth, maybe they were talking about how much power the sun generates in its totality. Yeah, maybe instead of my small minded approach of erecting earth-bound solar panels, they are talking about enveloping the sun in solar panels or maybe putting it in a big bucket of water to make steam and drive a turbine. Uh huh. Ok, let’s do the numbers… Oop! Wrong again! The sun generates 3.7 x 1026 watts (reference, and), which is only 3 orders of magnitude different from their 4.0 x 1023 quote, but still waaaay off. Now our planet is cast into an eternally bleak cold night freeze. Did you see the 2007 intense science fiction thriller Sunshine? It was pretty awesome, riveting and haunting; my mind still conjures up images from the movie; it is definitely worth seeing and it is just like the dark world the SolarWorld people apparently live in.
All this goodness from “America’s largest solar manufacturer since 1975”. Nice.
Before I forward this blog post to BART and SolarWorld, telling them to quit frigging lying, could someone check my numbers?
(note to self, I saw this on BART Train 1766x)
You are confusing Power with Energy…
Watts are measurement of power (as in the equation “Wattage = Voltage X Amperage”).
watt-hours (or kilowatt hours or watt seconds, etc) are a measurement of energy…
As in using a 100 watt (power) lightbulb for one hour involves the use of 100 watt-hours (0.1 kW/hour) of energy
Mo, when I read “kilowatts per second”, I take that to mean “kilowatts divided by seconds” or kW/sec. And that term is nonsensical here. “Kilowatt hours” or kW*sec is a useful term of energy. I don’t believe I’m confused on that. Convince me otherwise.
I don’t think I understand your point.
Nice post. FYI, I noticed the same BART ad and just wrote up a similar take on my blog Energetics, and linked back to your post here. I also emailed Solar World and asked them to get back to me with their math.