Dinner as a Service – Electricity Costs

This post is part of a project I’m calling ‘Dinner As A Service.’
Posts:
Overview
Electricity Costs
Electronics  

I was recently looking at a sous vide recipe that says to cook for 72 hours.  SEVEN-TY TWO HOURS.  Holy crap that’s a long time.   I don’t care how tender that meat would be after that – that is a long freaking time. The wife had the same thought I did…..what would THAT cost?!

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Interesting thought – how economical is this frankenCooker I built?   After some calculations, surprisingly efficient I found!   I’ll be the first to admit these were somewhat quick numbers, and I may be WAY off in one or more areas but after triple checking it looks right to me.  This post is going to explore these numbers, so if you are only reading for the fun VMware stuff you should skip this post.

The electric company bills me metered by a unit of kilowatt hours (kWh). My bill for the current time of the year totals to about 0.09$/kWh.   According to this site, kWh =  (watts * time) / 1000.  So that’s what that means.    I picked up a basic Kill A Watt that measures amps, watts, etc.   I measured the usage of the system at full power heating capacity and found the slow cooker I’m using uses WAY less power than I thought.  In total about 360 to 363 watts.     That’s interesting, and I can calculate would it would cost to run at full power over time but the cooker doesn’t constantly run when the meat is cooking, it only kicks on when needed.   Luckily, the Kill A Watt has a way of  keeping track of time since you turned it on and calculates kWh for you.

So here’s what I did.  As a test I started the cooker just as I would for real.  I filled it with hot tap water that cooled to about 109f by the time I got everything ready.   I set the target to 140f and made note of the time.  44 minutes later I got the notification we hit the target.  Awesome, so I can calculate the cost to warm (I used by own calculations for this part, not the kill-a-watt)  362 watts * (44/60) = 265.4666 Watt hours,  convert to kWh and we get 0.2655 kWh,  times the 0.09 $/kWh and it cost $0.024 to heat.

Next I unplugged the kill a watt (to reset the time, I used the basic device that doesn’t have any advanced functionality), plugged it back in and made note of the time.  I came back an hour later and checked what the meter said: 0.08 kWh.   In other words, in that hour the slow cooker (and other electronics) only used 0.08 kWh.  That’s way less than the constant full power on to heat which is expected.

2014-02-12_Calculations_final

Let’s say I wanted to cook the 72hour BBQ.   We could estimate the cost by (0.08 kWh * 0.09$/kWh) * 72 hours…. Something like just under a dollar  ($0.962).   Well how about that.  Again, assuming I didn’t make any errors (which I more than likely did), this thing really doesn’t cost much to run.   Way less than it would cost in propane or wood to do it on a grill or smoker I’m sure.   And this test was done without the space blanket looking wrap I use to retain heat!

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2 thoughts on “Dinner as a Service – Electricity Costs

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