Cost of Energy Experiment

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Jps101

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Cost of Energy to Produce 5 gallon batch:

Let me set the stage for you. I love the idea of converting my system over to electricity. As I read the posts on this site I am amazed at some of the backgrounds on here, Mechanical Engineers, Electrical Engineers, Chemists and the list goes on. My background is finance…in other words part of the fun in this hobby for me is the cost of things and how can I produce something as cost efficiently as possible. I think we would all agree once we start adding our respective incomes on an hourly basis – the cost of goods sold line in the income statement would change dramatically. Nonetheless, this thought process led me down the rabbit hole to see if I could try and figure out the economic viability of changing my system over to electric to bring my cost per beer down. Might also serve as an argument to the wife why I should spend 2k upgrading service, equipment, etc. Enough of the background, let me get on with the experiment.
Some of the base information: I live in Southern California, which means my electric service comes from Southern California Edison, my Natural Gas service comes from So Cal Gas and my propane is provided by Camping World just down the street.

Current Cost of Energy:
1 kWh from SCE = $0.21 (average cost over the tiers that we use)
1 Therm of Natural Gas = $0.72/.85 (NG is 15% less efficient than propane) = $0.85 (rounded up)
1 Therm of Propane = $3.34 (1 gallon of Propane = 91k BTU’s @ $3.67 gallon / 100k)

A few quick conversions of kWh to therms:
1 kWh = 3,414 BTU’s: 100k BTU’s = 1 therm: 100k/3,413 = 29.3 kWh: 29.3 kWh = 1 therm

Step One: Conversion to standard measure of energy cost
Natural Gas: $0.72/therm
Propane: $3.34/therm
Electricy: 29.3 kWh * $0.21 = $6.15/therm

Step 2: Convert 8 gallons of water from 60* to 160* (strike temp)
Need 1 BTU to raise 1# of water 1*F; Water weighs 8.34#/gallon
8 gallons * 8.34# = 66.72# of water
66.72 * (165*- 60*) = 7,005.6 BTU’s needed to raise 8 gallons of water from 60 degrees to 160 degrees
7005.6/100,000 = .0701 therms

Cost to raise water to strike temp (highest to lowest)
kWh: 0.43; LP: 0.23; NG: 0.06

Step 3: Bring Wort to a Boil (I am at elevation water boils at 210)
(210 – 152 mash temp) = 58* x 66.72 weight of water = 3,869.76 BTU’s needed to boil
Cost = kWh: 0.24; LP: 0.13; NG: 0.03

Step 4: Maintain boil for 60 min
Admittedly, this is where I ran into a bit of an issue, and perhaps where the math may fall apart a bit. I had a difficult time coming up with a formula to calculate heat loss and reduced energy needed to maintain a boil once reached. Therefore, I went with 60%. Why 60%. I have seen numerous times on this forum, where brewers will set there PID’s to a 60% cycle setting. That is what I went with.

Using a 5500w element, running for 60 min to calculate energy used.
5500 * .6 = 3300w / 1000 = 3.3 kWh * 3,413 (conversion factor of kWh to BTU) = 11,263 BTU’s
11,263 BTU’s / 100k = .1126 Therms * $6.15 = $0.70 to maintain a boil for 60 min.

Natural Gas:
.1126 therms (from above calc) * $0.85 (cost of a therm) = $0.10 (rounded up)

Propane:
.1126 therms * $3.34 = $0.38

TOTAL COST OF ENERGY TO BREW A 5 GALLON BIAB BATCH:
kWh = $1.37
LP = $0.74
NG = $0.19

Conclusion:
I need to come up with another angle to sell the conversion to all electric to the wife, the math isn’t gonna do it!

On a somewhat more serious note, I would like to think I thought through this pretty well. I had to make a few assumptions here and there. Nonetheless, it was a fun exercise doing the conversions and just seeing how expensive electricity has become in So Cal. Not to mention seeing how much energy is required to complete certain tasks. By the same token, how inexpensive Natural Gas has become. If I were to purely make decisions only on the math, there is no discussion, I could easily argue I should run a natural gas line to where I brew and doing everything on Nat gas. Further, I should look to convert over to Nat Gas fired electricity. I did not take into consideration heat loss to pots, ambient temp, and yes I know those will play a role. However, when you look at the disparity in cost, there is no way whatever inefficiencies there might be with NG it is highly unlikely in my opinion they will overcome the expense of electric. That said, time to convert to all-electric, why? Just too cool not to!

:ban:
 
I don't see any adjustments for efficiency. An outdoor burner on a pot is 50-60% efficient on a good day. Add some wind and you're lucky to get 25%. An immersed element will give you almost 100%

I doubt you'll be able to beat the cost of NG, but propane should be an easy foe. I decided on electric because of the ease of automation. An SSR relay is cheap vs an automatic gas valve.
 
I like the level of thinking that went into this.

My math is a bit simpler but here is my cost for brewing All Grain using propane:

Cost for 15 lb propane fill: $14.50
# of gallons brewed on one fill: 46.2 (11 gal batches x 4.2 batches/cylinder observed average)
Cost per gallon: $0.31.
Cost per 12 oz bottle: $0.03
Ingredient cost per 12oz bottle: $0.23
Total cost / bottle $0.26
% cost (energy) 11.5%

Conclusion: Energy is just over 10% of total cost to brew. To reduce costs looking to cut ingredient cost is a more effective way of cutting total costs. :)
 
I don't see any adjustments for efficiency. An outdoor burner on a pot is 50-60% efficient on a good day. Add some wind and you're lucky to get 25%. An immersed element will give you almost 100%

I doubt you'll be able to beat the cost of NG, but propane should be an easy foe. I decided on electric because of the ease of automation. An SSR relay is cheap vs an automatic gas valve.

It's really easy to weigh the tank before and after brewing to know the amount of propane used. No reason to guess. Then you can back-calculate the number of BTUs that were used and you'll know your effeciency.

I see 0.1 therm above, which looks like 0.1 gallon, which I think is less than half a pound of propane. That can't be right, so maybe I'm missing something (I admit to skimming the math above).
 
I don't see any adjustments for efficiency. An outdoor burner on a pot is 50-60% efficient on a good day. Add some wind and you're lucky to get 25%. An immersed element will give you almost 100%

I doubt you'll be able to beat the cost of NG, but propane should be an easy foe. I decided on electric because of the ease of automation. An SSR relay is cheap vs an automatic gas valve.

Agreed. I plan to brew on Christmas day or day after and figured I would take some copius notes on weight of tank before/after as well as time measurements. Like i stated in the OP, I was looking to have a little fun with this and I know I am missing a few pieces. Efficiency of energy source being one of them.
:mug:
 
I'm about 2 weeks ahead of you on this (just picked up an enclosure so I can start assembling) and I've run the numbers a few times myself. Propane is about $4/gallon for me and I'm guessing I use about a gallon give or take per 5 gallon session.

5500w @ $.20/kwH cycled @ 50% is about $.50/hr. About 1/4 the cost of propane for me. I figure if I drink 9383 more beers I'll starting getting a return on my investment.

And then it's like printing my own money!!!
 
I did this math as well, and I would have to get new service put in from SCE, including a new main breaker panel as the one on the side of the building is already full, in addition to running new lines out to wherever to carry 240V, and assembling/retrofitting my rig to use electric instead of propane. And, then I have to disconnect or otherwise disable that 240V line when I move, since it will be in a rental unit and I don't want to pay to run someone else's welder. The cost is in the multiple thousands. It is actually cheaper for me to wait until we buy another house where we are likely to have 240V already installed, or at least where I have enough extra capacity in the service that I can add a 240V outlet without much trouble.


Also in your calculations, you really do need to account for efficiency. I am pretty sure I've never gotten 10+ batches of beer on a single propane tank. 4-5, maybe. I'd say most often it's in the 3-4 range.
 
As one of those engineers, I love the math. It was brought up, but the efficiency is important here. Near 100% of the energy from the electric element goes straight to the water. A burner pumps a lot of heat into the atmosphere before even heating the water.
 
Agree with most of what you all are saying. My first, very basic calculation went something like this. I have filled up the propane tank 2x. Average cost per gallon of fill is 3.67 tax included. If I back into some numbers. Ie take a full propane tank, use it, go get it filled, added 3.34 gallons of propane. Thus I used 3.34 gallons to produce 37.5 gallons of finished beer, strange but true. Another way of thinking about it 11.2 gallons / gallon of propane. At $3.67 average cost per gallon propane = 32.7 cents per gallon X 5 gallon batch = $1.64 per five gallon batch of beer. Or another post stated in my case about 3 cents a glass. I am on my way to refill propane and will adjust some of the math upon my return.
 
TOTAL COST OF ENERGY TO BREW A 5 GALLON BIAB BATCH:
kWh = $1.37
LP = $0.74
NG = $0.19


Wow, 19 cents to brew a batch w/ NG, how much $ was spent heating up the neighborhood while brewing the 19 cent batch. Excellent work, but your example assumes 100% of the combustion going into the beer. Happy accounting and brewing!:mug:
 
As one of those engineers, I love the math. It was brought up, but the efficiency is important here. Near 100% of the energy from the electric element goes straight to the water. A burner pumps a lot of heat into the atmosphere before even heating the water.

BTW - been following your build very closely - very much like the design!
 
Just an FYI. This is a copy/paste from a post I made a couple of years ago here.

Some useful info:
  • Burners are actually rated by "BTU/hr". "BTU" doesn't technically make sense since the longer you run the burner, the more BTUs expended.
  • 1 pound of propane contains 21,591 BTU of energy.
  • 1 gallon of beer weighs 8.34 pounds.
  • (Pounds of beer ) * (Temp change in F) = number of BTUs.

To determine the BTU ( per hour ) of your burner:

  1. weigh your tank (W1)
  2. Run your burner full tilt for exactly 1 hour. Doesn't matter what you are using it for. Maybe heat up some water or something.
  3. Weigh the tank again. (W2)

Burner Output (BTU/hr): (W1 - W2) * 21,591


To determine how many BTUs went into the beer

  1. Determine weight of beer (see interesting info above) (W1)
  2. Record the starting temp of your water. (T1)
  3. Bring your water up to 200 (roughly) degrees. Best not to boil.
  4. Record the final temp of water. (T2) Make sure to stir briefly before measuring to ensure homogenous mix.

Utilized BTUs: W1 * (T2 - T1)


Heating Efficiency
This is the efficiency of your burner / boilpot combination.

Efficiency = Utilized BTUs / Burner Output * 100%​


Note: If using Natural Gas, replace the 21,591 with 20,161.

It's possible your burner is 56000 BTU. Flame burners throw most of their energy into the air and not into the pot.

Electric, BTW, is 100% effiicient: it all goes in the pot.
 
And you also must figure intangibles.

Coolness factor of a blinged out electric system >= 5$ per brew session credit
The look on peoples faces as they see said system = 2$ per brew session credit
Sitting in the ac when its 105 outside or in the heat when its dumping rain = priceless

Im in socal as well and ran my first brew day last weekend.... it is seriously nice to brew in the kitchen with a laptop
 
If time is money, it takes about 25 minutes for me to heat up 15g of strike water from 50-170 in my electric HLT. I guess that goes with the efficiency of heat transfer. No way I could do that with propane.
 
Electric may be 100% efficient on heating, though I'd argue some energy goes to heating the element itself, the cord, etc.. But I digress - even if we say it's 100% heat transfer to the water, you still must account for losses to the atmosphere via the kettle walls and lid.
 
What about the cost of gasoline and the share of automobile maintenance attributable to trips to refill your propane tank?
 
I figured the cost awhile ago and found that if I brew after 10 at night I can use the stove for the strike water and sparge water. I use propane to boil but at worst it is a 90 minute boil and I get over 10 brews easy per bottle doing it that way. Any way it is dang cheap doing it after 10

It would be cheaper to brew it all on the stove but the boil I get with 6 gallons is rather wimpy to say the least. That and while I love the smell of the boil my wife just does not appreciate so much.
 
Electric may be 100% efficient on heating, though I'd argue some energy goes to heating the element itself, the cord, etc.. But I digress - even if we say it's 100% heat transfer to the water, you still must account for losses to the atmosphere via the kettle walls and lid.

Yes, but you are going to get the same losses for any heating method so it's kind of irrelevant if all you are concerned about is relative cost.
 
BadNewsBrewery said:
Electric may be 100% efficient on heating, though I'd argue some energy goes to heating the element itself, the cord, etc.. But I digress - even if we say it's 100% heat transfer to the water, you still must account for losses to the atmosphere via the kettle walls and lid.

If you follow electrical code, thermal losses in wiring are negligible. Don't waste a brain cell.

All other things being equal, the thermal loss out of the kettle should be the same for identical kettles under identical ambient conditions. If I were to brew outside with NG on a day where the temperature and humidity were identical to my basement electric brewery (and no wind) all of those loss terms are identical and can be ignored.

Thermal mass of the element is similarly not significant when you have a ~1 lb element with 80+ lbs of water (1% error).
 
If you follow electrical code, thermal losses in wiring are negligible. Don't waste a brain cell.

Might want to measure before you make that assumption.

Loss due to resistive losses in power transmission:
I've measured the power (voltage and current) to my element. After line losses and control box losses, I get 5140 Watts out of my 5500W element.

Loss due to ambient:
Also, based on a bunch of empirical testing, I lose almost exactly 10% of the applied energy to air from my uninsulated boil pot (keggle - 60-degree day). So, I only get about 4600W of the power towards the boil. This 10% couple be recouped by insulating the keggle, which you can do easily. Not so easy with a flame though.
 
Love that I have created some discussion around this. As i stated at outset...no doubt electric is cooler. Incidentally, a gallon of propane weighs 4.4# at 60* F. 1 gallon of Propane will produce 91k BTU's.

Passedpawn: like you said, how often (if using a burner) do we really have it going full bore? Rarely. Just got back from propane refill - 3.49/ gallon ended up with not quite a full fill. Will start off the brew day with 4.5 gallons and will measure along the way.
 
Here's a good article explaining how to boil water.

http://www.treehugger.com/clean-technology/ask-pablo-electric-kettle-stove-or-microwave-oven.html

The electric kettle is by far the most efficient, but our argument is more about cost vs. efficiency. An argument can be made about on-site utilization of fossil fuels vs. burning at a power plant, then suffering further distribution losses before we plug in our pretty little tea pots.

Without natural gas on site, electric is the clear winner for me. However, it's going to take a heck of a lot of beer before I see a return on my investment.

That, my friends is what you call a win-win.
 
The pennies difference on actual energy costs are of no real significance, the time and convenience factor are the savings. My current number for the cost of my time is $200 per hour when deciding on how to use it. If I have to spend a half hour getting a propane tank filled, I just spent $100 not to mention gasoline and whatever other errand my wife will sneak in on me :). Having plenty of electric power to heat up my gear whenever I want in the comfort of my shop in a fraction of the time it takes on a burner in my driveway has been well worth the money I spent building it. I now have extra time to spend on other activities, it was a no brainer for me.

I can't believe people are trying to figure out how much heat they are loosing through their power cords. That's some heavy ****. lol
 
If you're going to take a scientific and in-depth look at something, you may as well be scientific and in-depth the whole way. You can ignore parameters all you want, as long as you're doing it CONSCIOUSLY and for a reason. So yes, I maintain that 100% of the element's power doesn't go to actually heating the water (not considering losses from the kettle to the atmosphere) - some goes elsewhere. You can chose to ignore it in your calculations should you chose, but make the choice knowingly.

The other point of discussion - an X rated element and a Y rated burner do not actually produce X or Y for values. Measuring the amount of BTUs consumed by doing a fixed heating and then measuring the tank, and comparing that to the rated value of he burner, does not give you an accurate number. Again - you can chose to ignore this, but it's worth discussing. Same with the element, as passedpawn[/b/] says - my 5500w element was likely not made in a high control, low tolerance laboratory... And my power supply isn't exactly 240.00v either.

Truly, the best way to do this would be to weigh a propane tank, complete a brew in whatever environment you normally brew in. Assuming it was an average day (IE, not snowing during a hurricane), you'd be able to weigh the consumed propane and know your cost. Do the same exact brew in whatever location you do your electric brewing in. Get one of those 'kill-a-watt' energy consumption meters and plug your panel into that. Measure the power consumption during your brew. Now you know exactly how much propane vs exactly how much electricity it takes to brew that one batch with your given equipment. Hypotheses are great, but there's no match for experimentally gathered empirical data.
 
mateomtb - I'm guessing it took you at least 10 hours or more to research, acquire parts, construct, and test your electric setup, above what it would have taken to do a propane setup. At your rate of $200 / hour, that's $2,000 worth of money... or 20 some trips to get a propane tank filled. Don't forget to count it both ways...
 
Get one of those 'kill-a-watt' energy consumption meters and plug your panel into that. Measure the power consumption during your brew. Now you know exactly how much propane vs exactly how much electricity it takes to brew that one batch with your given equipment. Hypotheses are great, but there's no match for experimentally gathered empirical data.

I've got a Kill-a-Watt (my keezer costs $1.22 / mo. to run!). It won't work for a 240V 30A appliance. I suppose you could juryrig it into one leg of the 240 though, but the current would burn it up pretty fast I'd guess.

It's not hard to figure out the cost of the electricity though. Once it gets to the element, ALL the energy goes into the water.
 
it seems like the answer is to build a fume hood and exhaust system in my basement....so I can have a natural gas fired brew system???

The build would be cheaper....and the operating cost lower
 
wow, you guys pay a lot for electricity!!!

Last bill $0.074380/kwh

You have no idea...

sce.jpg
 
I actually have an Electricity Delivery Charge plus an Electricity Supply Charge...

If I add up and divide by kwh used it comes up to $0.1461/kwh.

974kwh = $142.30

Your clearly still more, but not as dramatically as it at first seemed, unless of course you have Delivery Charges on top that.

Chris
 
I actually have an Electricity Delivery Charge plus an Electricity Supply Charge...

If I add up and divide by kwh used it comes up to $0.1461/kwh.

974kwh = $142.30

Your clearly still more, but not as dramatically as it at first seemed, unless of course you have Delivery Charges on top that.

Chris

Not included in this pic is the delivery charge etc. I'll have to look a little closer. I didn't include that as I figure that is not anything additional. I was simply looking at the additional marginal cost if you will. Which by the way, you can see the higher tiers are crazy.
 
The pennies difference on actual energy costs are of no real significance, the time and convenience factor are the savings. My current number for the cost of my time is $200 per hour when deciding on how to use it. If I have to spend a half hour getting a propane tank filled, I just spent $100 not to mention gasoline and whatever other errand my wife will sneak in on me :). Having plenty of electric power to heat up my gear whenever I want in the comfort of my shop in a fraction of the time it takes on a burner in my driveway has been well worth the money I spent building it. I now have extra time to spend on other activities, it was a no brainer for me.

I can't believe people are trying to figure out how much heat they are loosing through their power cords. That's some heavy ****. lol

At $200/hr, I am guessing the time value of the beer you are brewing pushes your cost per beer out of this world...ha ha.

:drunk:
 
So as promised I did a brew yesterday and was pretty methodical about collecting what I thought was relevant data.

I have tried to post a pic of the excel spreadsheet below. In summary I used approximately 74,633 BTU's with my set-up. The set-up being a 10.5 gallon Polarware Kettle and a Blichmann Floor Burner. Couple of key points:

Time to heat 8 gallons of water from 59* to 160* = 29 min
Time to Heat 8 gallons from 152* to 166* = 11 min
Time to Heat and Boil ~6.75 gal for 60 min, took 80 min, raised temp from 162*

A pound of propane = 21,951 BTU's. If I leave out the boil portion for just a moment and simply calculate energy used to raise temp from point A to point B, I think I can come up with some efficiency numbers. A quick refresher. 1 BTU = energy used to raise 1 gallon of water 1* F. 1 gallon = 8.34#. Therefore, 8 gallons of water x 8.34 = 66.7#. If I do the math for the heating of strike water and mash out water, in a 100% efficient system you would only use 7,670 BTU's. Based on the weight of the tank before and after, I used 1.6# = 35,122 BTU's. Thus, heating with Propane is 21.8% efficient, right? I am pretty sure my math is correct.

So here is the comparison:

Propane @ 3.57/gallon = $2.93 for this brew
NG = $0.90 (assuming same efficiency + 15% for difference between LP and NG)
Electricity = $0.80 (using some very loose estimations)

In the end, assuming some of my estimations are correct, due to heat loss as many suggested, going all electric can save (in my case) almost $2.10 per 5 gallon batch. Needless, to say, breakeven is a ways off. However, as some suggested the bling factor alone will more than cover the cost.

Thanks to all who chimed in on this. I hope it was a bit of fun to think of our brew days in yet another way.

Cheers!
:mug:

Admittedly in order to do a apples to apples comparison, I would need to conduct same experiment with an electric element.
 
Very unscientifically, I've found it costs me $3per 5gallon batch of propane. Since I bank my yeast and buy grain and hops in bulk, an average medium beer costs me under $15 to brew.

Bottling or kegging works out to about the same price (co2 vs caps and sugar).

I'm under .30 a bottle for most brews. I'm happy with that.

I have considered going electric, but right now isn't the best time for me. Thanks to everyone's contributions on this thread!
 
So as promised I did a brew yesterday and was pretty methodical about collecting what I thought was relevant data.

I have tried to post a pic of the excel spreadsheet below. In summary I used approximately 74,633 BTU's with my set-up. The set-up being a 10.5 gallon Polarware Kettle and a Blichmann Floor Burner. Couple of key points:

Time to heat 8 gallons of water from 59* to 160* = 29 min
Time to Heat 8 gallons from 152* to 166* = 11 min
Time to Heat and Boil ~6.75 gal for 60 min, took 80 min, raised temp from 162*

A pound of propane = 21,951 BTU's. If I leave out the boil portion for just a moment and simply calculate energy used to raise temp from point A to point B, I think I can come up with some efficiency numbers. A quick refresher. 1 BTU = energy used to raise 1 gallon of water 1* F. 1 gallon = 8.34#. Therefore, 8 gallons of water x 8.34 = 66.7#. If I do the math for the heating of strike water and mash out water, in a 100% efficient system you would only use 7,670 BTU's. Based on the weight of the tank before and after, I used 1.6# = 35,122 BTU's. Thus, heating with Propane is 21.8% efficient, right? I am pretty sure my math is correct.

So here is the comparison:

Propane @ 3.57/gallon = $2.93 for this brew
NG = $0.90 (assuming same efficiency + 15% for difference between LP and NG)
Electricity = $0.80 (using some very loose estimations)

In the end, assuming some of my estimations are correct, due to heat loss as many suggested, going all electric can save (in my case) almost $2.10 per 5 gallon batch. Needless, to say, breakeven is a ways off. However, as some suggested the bling factor alone will more than cover the cost.

Thanks to all who chimed in on this. I hope it was a bit of fun to think of our brew days in yet another way.

Cheers!
:mug:

Admittedly in order to do a apples to apples comparison, I would need to conduct same experiment with an electric element.

Spreadsheet

2012-12-27_184545-57766.png
 
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