Electricity costs for Popper roasting

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
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#1: Post by randytsuch »

Decided to share some quick calculations I did to estimate my roasting electricity costs, using a popcorn pumper,

My popper is supposed to be 1400w, but I haven't actually measured, rounded up to 1500w, so I could use 1.5 kwh.
Since I use PWM and PID to control temps, heater isn't on all the roast time, and actual use will be less.

My normal roast size is around 125 grams = 0.275 pounds, I rounded down to 0.25 pounds. So four roasts to get one pound.

Roast time is around 12 mins, rounded up to 15 mins, so 4 roasts per hour of electricity use, comes out to one pound per hour

So I roast 1 pound per 1.5 kwh

My electricity cost is 25 cents per kwh, so about $ 0.38 electricity cost per pound for me.

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#2: Post by BrewingMatter »

That is not bad at all.
I have not done my math on electricity.

My roaster is 500w and it roasts 250g or about half pound.
My electricity cost is $0.10151 per kWh, so I can roast for 2 hours straight for 10 cents!
2 hours usually nets me 3 pounds, so roughly 3 cents per pound.

randytsuch (original poster)
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#3: Post by randytsuch (original poster) »

I was worried it might be significant, was surprised how little it was after doing the math.

Now I'm wondering how efficient my roaster is, I expect its very inefficient.

Would need to know how many watts is really used to roast one pound (or 1 kg or whatever) of coffee.


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#4: Post by BrewingMatter »

You know, I upgraded to my current roaster(BocaBoca 250g) from Popper roaster because I asked the same question.
Something about 1500W to build the heat to lose it all to the open air did not feel right.
BocaBoca roaster uses an infrared lamp to build up the heat, and because no component actively moves air, the heat tends to stay near the coffee so that it can be energy efficient.

However, having said that, both roasted coffee beans just fine, and now I know the cost of electricity is near nothing on both.

Three cents or 38 cents to roast a pound of coffee sounds about the same to me.
In the end, when you roast your own, you save a chunk of $ regardless.

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#5: Post by Milligan »

Energy costs for roasting are quite small considering the other expenses involved. For example, I'm around 150 roasts in on my cormorant and still have plenty left in my 20lb propane tank. I'm not sure what today's rate is, but I filled it for $17 last time. That is around 10cent per roast in energy. The cormorant uses a 12V system for the drum and fans so that is likely in the single digits per roast or negligible.

randytsuch (original poster)
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#6: Post by randytsuch (original poster) »

Yeah, cost is a non issue.

Was wondering because I've seen posts here about recycling exhaust to recover heat energy. Guess if you roast on a large scale its more of an issue.

So its more of a green thing, if I want to try to save energy. Have thought about making a SCTO type roaster, I have the SC part of it already. I'm sure it would be more energy efficient. Might be time to go looking for a TO and try it out.

Looking at BrewingMatter's numbers, his roaster is 3-5 times more efficient than my popper, so something to think about.


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#7: Post by Marcelnl »

over here in the EU energy cost looks different....Propane went up to like 60 euro for 10Kg. Still , cost of roasting is a non issue when comapring to professional roasters prices for roasted coffee.
LMWDP #483

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#8: Post by Mbb »

Personally, i like to evaluate it in terms of how many seconds I worked to pay for it. Then I realize I wasted much more time calculating that than I worked to pay for it in the first place.

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#9: Post by pcofftenyo »

My Popper as a Roaster pulls 1150 watts max, 77% of 1500w max rating.

Would be nice to have that extra 23%.

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#10: Post by Pressino »

I highly recommend using something like the Kill-a-Watt meter to measure exactly how much power your roaster draws for each roast session, especially if it is thermostatically controlled or has some ability to vary heat and/or fan speed. On my Quest, which is rated at 1150W and does allow heater current and fan speed control, an 8oz roast to full city plus (including pre-roast heat up to charging temperature) requires no more than 0.5KWh. Doing back-to-back roasts obviates the need for pre-heating subsequent roasts, so I can easily roast more than a pound for less than 1.0 KWh.

I think the average US cost for electricity is 12-14 cents per KWh. Here in California we pay twice that average cost. Thank you PG&E and whoever serves the other parts of California!