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 Home Brew Forums > Cost Savings in Electric?

11-10-2011, 05:21 PM   #1
BucksPA
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 Cost Savings in Electric?

My Brutus 10 clone was can be viewed in my signature runs off of propane. I typically get 1.5 seperate brew sessions for each Lowe's purchased propane tank. Each tank costs \$20 and each brew session is used for heating up sparge water (9-10 gallons), strike water (4-7 gallons), and used for a vigorous boil at about 11% evaporation rate per hour, typically 60 minute boils.

I brew a lot and am have 3 tanks on hand, but am spending so much on propane I wonder if there are cost savings with electric versus propane.

Can an electric setup be used for less than approximately \$13-15 per session?

If you really want to get technical, mr electric runs 10 cents kw.

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11-10-2011, 05:52 PM   #2
hatfieldenator
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In my opinion electricity has got to be cheaper than all that propane. If you wanted to do a rough estimate on math just assume it takes 30 minutes to heat up your system, 60 mins for a mash, another 20-30 to heat up to boiling, than 60 minutes of boiling. Assume you're using 22amps at 240V's that entire time and you can try to estimate costs.
If I'm doing my math right, using an online calculator, thats 5280Watts of energy for 3 hours at 10cents per kwh would add up to about \$1.58 in electricity charges for a 3 hour brew session. Of course this will vary greatly with how long it actually takes depending on the amount of water you're heating and boiling and how cold the water is to start. Even if it takes you 4 hours you're still only talking \$2.11

If anyone else wants to chime in here and do their own calculations it would be helpful to see if others agree with this very rough estimate. But, it looks like it would be much cheaper overall.

http://www.webmath.com/kwh.html
http://www.supercircuits.com/resources/tools/Volts-Watts-Amps-Converter

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11-10-2011, 06:09 PM   #3
thughes
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Less than \$1.00, according to this thread:

http://www.homebrewtalk.com/f170/40-paces-brewery-single-vessel-e-biab-252920/index2.html

I was getting @ 3-4 brew sessions per tank before I went electric recently. I've since done 5 batches and love not having to worry about propane supply.

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11-10-2011, 06:10 PM   #4
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I have a RIMs system similar to www.theelectricbrewery.com. I have a panel mounted amp meter. I would agree with the analysis above. However, with PID control rarely are the elements running at 100%. Even though my brew day is approx 3 hrs, the only time the elements are at 100% is during the intial strike water warming, and warming up the bk to boil. My rims tube once it hits the mash temp pretty stays < 10% PID. I set my BK down to 60% PID once I hit a boil. With all that in mind I would take the 1.58\$ above and drop it well below 1\$.

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11-10-2011, 06:17 PM   #5
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Math looks good, I'd say you're even way overestimating since most E-rigs don't run wide open at 22-23 amps for most of the time. For most of the mash you're at 10-20% power to maintain temps, (could be a bit less or more depending on insulation), and for boil you're at 50-75% depending on how vigorous a boil and again insulation.

The other way to look at it is: You will need to raise 15 gallons of water from 10C to 100C, and boil 1.5 gallons of it into steam.

15 gallons of water is 56.8 kg. Water's specific heat is 4.18 kJ/kg/K, you are going from 10 C to 100C which is 90K delta. So you need 21,368 kJ.

Latent heat of vaporization is 2260 kJ/kg, 1.5 gallons of water weighs 5.68 kg. Energy to boil is 12,836 kJ.

So total is 34,204 kJ. Assume 80% efficiency to account for heat loss, you're at 42,759 kJ. One watt is 1 J/s. One kW is 1 kJ/s. so you need 42,759 kW*s, divide by 3600 seconds in an hour and you need 11.88 kW*h. At \$0.10/kW*h, that's \$1.19.

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11-10-2011, 06:32 PM   #6
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electricity without argument is cheaper than propane. The cost of your system depending on complexity can negate the savings. I built my system b/c thats the system I wanted and would never go back to propane. Cost savings on fuel is not in my oppinion alone the best reason to go electric. except for inexpensive heat sticks the cost of equipment would eat up the fuel savings.

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11-10-2011, 06:46 PM   #7
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Quote:
 Originally Posted by shortyjacobs Math looks good, I'd say you're even way overestimating since most E-rigs don't run wide open at 22-23 amps for most of the time. For most of the mash you're at 10-20% power to maintain temps, (could be a bit less or more depending on insulation), and for boil you're at 50-75% depending on how vigorous a boil and again insulation. The other way to look at it is: You will need to raise 15 gallons of water from 10C to 100C, and boil 1.5 gallons of it into steam. 15 gallons of water is 56.8 kg. Water's specific heat is 4.18 kJ/kg/K, you are going from 10 C to 100C which is 90K delta. So you need 21,368 kJ. Latent heat of vaporization is 2260 kJ/kg, 1.5 gallons of water weighs 5.68 kg. Energy to boil is 12,836 kJ. So total is 34,204 kJ. Assume 80% efficiency to account for heat loss, you're at 42,759 kJ. One watt is 1 J/s. One kW is 1 kJ/s. so you need 42,759 kW*s, divide by 3600 seconds in an hour and you need 11.88 kW*h. At \$0.10/kW*h, that's \$1.19.
I think my head just exploded.
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11-10-2011, 06:57 PM   #8
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Quote:
 Originally Posted by shortyjacobs The other way to look at it is: You will need to raise 15 gallons of water from 10C to 100C, and boil 1.5 gallons of it into steam.
since I love nit-picking, I'll just add that you won't raise all 15 gallons to 100°C: some will be absorbed by the grain. But otherwise, that's exactly how I would calculate the cost.
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11-10-2011, 08:36 PM   #9
BucksPA
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my system cost \$2300 to build from the groun up. I dont care though, because hobbies aren't cheap. If i wanted to brew beer to save money, I'd be brewing corn and rice beers. However, when it comes to down to brew day (twice a month), I'd love to get that cost down to \$60 for 10 gallons versus \$80.

So what you guys are telling me is great news. The cost to build on the front end doesn't matter as much as the cost on the back end every time i brew.

That's a big difference \$13 per session versus \$1 or \$2 max.

thanks.

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11-10-2011, 08:58 PM   #10
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Quote:
 Originally Posted by zeno27 since I love nit-picking, I'll just add that you won't raise all 15 gallons to 100°C: some will be absorbed by the grain. But otherwise, that's exactly how I would calculate the cost.
lol, I knew someone would pick up on that.

See, trick is, you're also having to heat grain up from ~10C to whatever the hell mash temp is in C....and I didn't feel like figuring THAT bit out. (Specific heat of barley, WTF? ). I suppose I could have figured it out by knowing how much, say, 25 lbs of 50F grain will drop the strike water temp, but that was too much work. I figured that by just saying I'm heating everything to 100C, I'll capture the absorption/grain heating bit under the umbrella .

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