Electric vs. Propane Brewing

After reading some of the threads on using electric heating elements to brew, I was curious how electric brewing compares to using a propane burner, both in terms of time and money. So, I did some thermodynamics homework and this is what I discovered. Feel free to point out any flaws you see. This wasn’t my best subject although its nice to finally find a use for it.

First, here are a few definitions to establish a common framework for this discussion.

It takes 1 BTU/hr to raise 1 lb of water 1 deg F.

1 gallon of water weighs 8.3 gallons, so it takes 8.3 BTU/hr to raise 1 gallon 1 deg F.

1kW = 3414 BTU/hr

So, to raise 5 gallons of water from 60 F to boiling would require 5*152*8.3=6308 BTU/hr.

This analysis does not take into account any thermal loss (cooling) because the loss would vary based on outside temperature, material of the vessel, surface area of the opening, etc. Regardless if you use electricity or propane, insulating your hot liquor tank and brew kettle will help you achieve your target temperature more quickly and maintain that temperature with less energy.

Propane burners are rated on BTU/hour or simple BTUs. They range from 35k-200k BTU/hr. This is the amount of energy produced by burning the propane, but not necessarily transferred to heat the water. So, it is not a perfectly efficient transfer to your HLT or boiling kettle. There will be further loss from the vessel itself since it is not a perfect conductor. It is difficult to determine the actual amount of energy produced by the burning propane that actually makes its way into heating the water. Therefore, I will make an assumption that only 50% of the energy produced by a propane burner actually heats the water. A quick google search turned up the King Kooker turkey fryer produces 54K BTUs/hr. Adjusting for efficiency, the propane burner provides 27,000 BTU/hr (54,000*.70). Based on this value, the propane burner could bring 5 gallons of 60 F water to boil in 14 minutes (6308/27,000*60min). Obviously, a more powerful burner will heat water more quickly, but with greater fuel consumption.

Electric heating elements are usually measured in watts or kilowatts (kW). A 4kW heating element would provide 13,656 BTU/hr (remember, 1kW = 3141 BTU/hr). The electric heating element would be much more efficient at transferring its energy into heating the water because it is submerged in the water and has negligible loss. Therefore, the 4kW electric element could bring 5 gallons of 60 F water to boil in 27.7 minutes (6308/13,656*60min).

However, which heat source is more cost effective?
Propane contains 21,622 BTUs per pound. (www.propanegas.ca/FileArea/PGAC/Propane properties.pdf )

Therefore, a 20 lb tank of propane would have 432,440 BTUs of energy. That is enough to run your 54K BTU propane burner for approximately 8 hours. Assuming $20 per tank, propane use costs $2.50/hr.

According to my last electric bill, I paid $.18 per kilowatt hour after taxes and fees. Using a 4kW electric heating element for one hour would use 4 kW hours of electricity and cost $.72/hr.

Electricity is certainly less expensive to operate but more costly in terms of time. Using my example above, electric brewing would increase the time to reach strike temperature for your mash by 10 minutes (21 min for electric vs. 10.6 min for propane). It would take an additional 6 minutes to reach boil after the sparge (12 min for electric vs. 6.06 min for propane). Sparge water can be heated during the mash so there is no time savings associated with propane. Overall, for a 5 gallon batch, you can expect to save about 16-20 minutes using propane over electric.

The only drawback to electric brewing I can think of is ready-made equipment is difficult to acquire. Propane turkey fryers with 28-32 quart pots are commonplace and relatively easy to operate. From what I have seen on the forums, most electric brewers use home-made equipment that can be dangerous if you don’t know what you are doing. If you chose to explore brewing using electricity, take appropriate safety precautions and understand the associated risks.

In conclusion, electric brewing offers an affordable alternative to propane. Although it may add a few minutes to your brew session, it offers the flexibility to brew indoors and in confined spaces where propane use would be unwise and likely dangerous. Finally, you don’t have to worry about running out of propane, as I am sure we have all done or will do during a brewing session.

Some common misconceptions in your calcs. But you did your work! I like it!

Here is a recent post that I put up to discuss some of the misconceptions about electric brewing.


Misconception:
ELECTRIC????? I don't get it. Out west it cost more and is less efficient. Gas is cheep and with 170,000 BTU gas burners you can't beat it. I have never heard of inexpensive electric burners that will put out that much. Electric? No way!!

Not true at all.

Gas burners are about 25% eff at getting BTUs to the kettle. Electricity is basically 100% efficient. A 170,000 BTU burner will produce the heating power of 43,000 BTUs, that is the extent of it. If a 170,000 BTU burner provided 170,000 BTUs of heat to your kettle, youd get 13 gallons from 60F to a boil in 6 minutes flat, and it doesnt.

Electricity in California is not that expensive. In Antioch you pay $.14 per kWh, here in Indiana I pay $.10 per kWh. That is quite average across this great land.

A 20lb tank of propane contains about 17 pounds of propane, or 374,000 BTUs. If you are going to net 25% of that, you are getting about 95,000 BTUs from that tank at a cost of about $16.

1kW is 3412 BTUs... so you need about 28,000W or 28 kW to equal the same 95,000 BTUs in a 20lb tank of propane. In Indiana that would cost me $2.80, in California that would cost you $3.92. If you pay $.57 per kWh, then it would be equal to the cost of propane anyhow.

Speed of heating. This is tied to BTU output, and since electricity is so much more eff. at getting the BTUs into the kettle to do work, you need a lot fewer total BTUs to get the same outcome.

A 9000W kettle like I have will heat 13 gallons from 60F to boiling in 34 minutes. That is 30,708 BTUs, the equivelant of a 123,000 BTU burner, at 1/5 the cost to operate.

Bottom line, electricity is fast, cheap and clean.

Ummm.... I just read this thread, and now I need a beer. Good information however.

The Pol, Jkarp, and Boerderij_Kabouter, are my heroes! I have decided to go all eclectric in my brewing adventure, it will take me a couple of years to get all of my e-equipment together, but you sirs are the three wise men of eBrewing!!! All the research is concrete when it comes to cost/efficiency ratios. Pol...Kill-A-Watt is beautiful, I have been following your thread, and all I can say is I envy your system, and I revel in its beauty and simplicity (minus the electronics, of course)

Anyhow, you guys keep up the great work, and continue to teach us that electricity (at least for brewing) can be our greatest ally.

Schnitzengiggle said:

The Pol, Jkarp, and Boerderij_Kabouter, are my heroes! I have decided to go all eclectric in my brewing adventure, it will take me a couple of years to get all of my e-equipment together, but you sirs are the three wise men of eBrewing!!! All the research is concrete when it comes to cost/efficiency ratios. Pol...Kill-A-Watt is beautiful, I have been following your thread, and all I can say is I envy your system, and I revel in its beauty and simplicity (minus the electronics, of course)

Anyhow, you guys keep up the great work, and continue to teach us that electricity (at least for brewing) can be our greatest ally.

Click to expand...

Thanks, that is flattering.

Schnitzengiggle said:

The Pol, Jkarp, and Boerderij_Kabouter, are my heroes! I have decided to go all eclectric in my brewing adventure, it will take me a couple of years to get all of my e-equipment together, but you sirs are the three wise men of eBrewing!!! All the research is concrete when it comes to cost/efficiency ratios. Pol...Kill-A-Watt is beautiful, I have been following your thread, and all I can say is I envy your system, and I revel in its beauty and simplicity (minus the electronics, of course)

Anyhow, you guys keep up the great work, and continue to teach us that electricity (at least for brewing) can be our greatest ally.

Click to expand...

The Pol said:

Thanks, that is flattering.

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I'm not as savvy as all of you engineering folks round here, so as long as I can count on your advice when time comes, the very least I can do is give some credit where credit is due!

Schnitzengiggle said:

I'm not as savvy as all of you engineering folks round here, so as long as I can count on your advice when time comes, the very least I can do is give some credit where credit is due!

Click to expand...

Kill-A-Watt is beautiful, more beautiful than I had planned... this forum has taught me well

A 9000W kettle like I have will heat 13 gallons from 60F to boiling in 34 minutes. That is 30,708 BTUs, the equivelant of a 123,000 BTU burner, at 1/5 the cost to operate.

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Reviving a dead thread...
How did you get 30,708 BTUs needed for heating 13 gallons of wort?

What I came up with is
13 gallons of water * 8.345 lbs/gal = 108.5 lbs

212-60=152 degF temp rise

108.5 * 152 = 16492 BTUs

I realize wort is heavier than water, but not that much, or am I missing something?

I'm tired of blasting through BBQ propane tanks at $15/tank, and am thinking about building an electric rig, which is cheaper even with Connecticut rates at $.25/KW! I might look into improving the propane burner efficiency first, though. Thinking about adding fins to the bottom like camping stoves.

It may take 16492 BTUs to raise the water from 60-212 given zero heat loss, which is impossible. Then, it takes extra BTUs to take it from 212 to boiling. I know it's 970 BTUs to turn a pound of water into steam.

I brew with propane (using the familiar 20 lb. cylinder) and have the potential of running a line from our 1,000 gal. bulk tank, which would cut my costs more than in half. However, there is absolutely no question that for efficiency, electric is the way to go. Providing a 240VAC / 30A circuit is no problem, & I've seen several pretty likely designs, but am looking for a boil pot that does a good job of accommodating an immersion chiller (and, no, I have no interest in plate, counterflow, or other "internal" chiller).

The Pol said:

Some common misconceptions in your calcs. But you did your work! I like it!
[...snip]
Electricity in California is not that expensive. In Antioch you pay $.14 per kWh, here in Indiana I pay $.10 per kWh. That is quite average across this great land.

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The way PG&E works, our electricity is ~$.18 (almost double yours) but, and this is important, only if I stay below the average of what I used last year*. If I start doing electric brewing, I go up to $.30 and, if I do a lot of electric brewing (say I set up a nano-brewery or some such), it goes to almost $.50

...Not just for the brewery (unless it gets its own account/meter), but for the whole house.

I'm also curious about your 25% efficiency number on propane. I get that a lot of heat goes up the chimney, but... 75% ?! Seems high. Do you have a source for that number?


* This seems kind of a scam to me since, if I use less, my average goes down and, if I use more, I pay 2-4x the rate.

Bottom line, electricity is fast, cheap and clean.

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Still investigating this one. I WANT to go electric, because of the fast & clean thing, but it's not clear to me that it's cheaper. Especially given California's punitive rate structure.

And now, having said all that, I just found this link which gives examples of a typical water-heater (propane) at 60% or (electric) at 90%

http://homeguides.sfgate.com/propane-vs-electric-water-heater-operation-costs-97798.html

Their examples show propane at about 2x what we're paying nearby (it is SF, after all! ) and, somehow, they're magically getting their electricity cheaper than I am (hey!), so now I have to question all of the article's assumptions.

That said, if we adjust the cost of propane to what I'm paying (Watsonville), they seem about even. If we adjust the electricity to my (normal, not inflated by over-use) rate, propane is slightly cheaper.

...But you have to deal with propane.

Like I said: I want electricity to be a better deal, things just aren't looking that way (yet! )

olie said:

And now, having said all that, I just found this link which gives examples of a typical water-heater (propane) at 60% or (electric) at 90%

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Are you sure propane is cheaper? I'm thinking that there are issues with correlating the efficiency of the water heater to that of a open propane burner typically used in brewing in that the water heater isn't heating water to boiling temps and is probably designed to better transfer the heat that is generated to the water vessel (as opposed to a big pot sitting on a burner out in the open).

Auburntsts -- yeah, I agree that, if it's just an open burner under a flat-bottomed pot, you're going to lose a ton of heat.

You can probably double efficiency just by putting a collar around the edge to keep the heat in.

I guess I'm thinking along the lines of: Let's compare best-case (most efficient design, high transfer rates) of electricity vs propane, not best of one and worst of the other.

Admittedly, "typical" or "common" is probably closer to best of one (an electric element immersed in fluid can't much well put its heat anywhere else!) and the worst of the other (propane on a typical "stove-top"-style setup) -- so I'll capitulate that; now I'm curious about best vs best.

If you're all talking about 5 gallon batches then the cost of both is basically nothing. Same as measuring mash efficiency. At 5 gallons it's meaningless.

Now if you're brewing 10 barrel batches 5 times a week, it's something to consider for sure

But a 5-10 gallons 3-4 times per month. Pick the one that's easiest and gives you the best consistency and run with it

Thanks. While I'm currently in the homebrew category, my interest is in the planning to micro-brewery vein.

As you say, if it's $1.25 for one and $1.60 for the other -- who cares?!

Nice resurrection of a 7 year old thread, but still a relevant discussion. Most people get about two brew days out of a 20lb propane tank. The tank won't be empty but you won't get a 3rd brew day on it so most people go swap it. Call that $8-10 a batch. On electric, I run 5500 watts for 20 minutes flat out. The element fires so infrequently during the mash, it barely counts. The ramp to boil is another 15 minutes flat out. Then for the hour boil, I run a bit over 50% duty on 5500. So, that's about 1.85kwh + 1.3kwh + 3kwh = 6.15kwh @ .14 = $.86

Even if you paid $1 per kwH, electric is cheaper. Don't forget about the running around swapping tanks and potentially running out mid brew.

It's a little disappointing that this has boiled down to a strictly cost type discussion.

I was hoping for a "this is why I went this direction..." type of thing.

I went with propane because of the heat generated from brewing I wanted to get my brew rig outside, and I wanted to be able to move it around as needed.

Also since I don't have any 230VAC outlets or any desire to have any, and running #10 extension for 115VAC is expensive, heavy and needs to be taken care of (kids, critters, etc.). Also, 115VAC takes longer.

Now, I do have some electric bits, but they are all low power and no danger to your typical extension cord. I don't use spark ignitors, instead I use Honeywell Firefly thermal ignitors. They are probably the single greatest drain on my system, but never for more than 15 seconds, at which my controls shut the gas valves on "fail to fire". The valves are only 14 watts and the entire electric side is less than 100 watts, exclusive of the Firefly's.

I also have 4 propane bottles on my rig manifolded together, so I can squeeze a bottle dry before switching over.

Never exchange bottles unless your's no longer passes inspection. Exchange outfits don't fill to capacity. The best value is to have your bottles refilled.

Now if I had 230VAC outlets available in a couple of convenient locations I might have gone electric. I work with industrial control systems and know a great deal more about electricity than I do about propane. That learning curve was steep and painful.

So... for me, it wasn't cost that drove the decision but rather the portability factor.

Also, there's something primal about having a flame!

Cost is a relevant factor in the conversation

I switched to electric and glad I did

I used to get at least 5 5gal batches out of a propane tank.

Going electric means I can brew in a >50F basement, rather than a <25F garage, just next to a utility sink. And also just next to the fermentation chamber, so I don't need to carry a full fermenter more than 5 feet. The grain storage is another yard further away, the brewing tools (scales, mill, hydrometers, salts, etc.) are on shelves just behind me. Hops are in the freezer 12 feet away.

And the control of the boil is much more consistent: I can predict and control the boil off with 10% by the power setting on the element (and the read out of current/power consumption).

I don't really have a place inside my house for a 3 vessel electric system nor was the electrical infrastructure in place for one.

I do have an easily accessible natural gas connection outside under my deck so I decided to build my 3 vessel structure outside and use NG for it. Weather, at least cold, is never a factor here. I brewed last Saturday in shorts and flipflops and since it was sprinkling I just didn't push my brew structure out from under the deck. I actually prefer brewing outside.

Natural gas is a pretty cheap energy source but probably a bit more expensive than electricity but like electricity I never run out of it. I also have a very nice brewhardware heat stick that helps heat things even faster so I guess mine is a hybrid system after all.

I started out using a Gas burner because I had one. The previous owner of my home had a hot tub on the deck and installing a 50 amp outlet in my basement was easy. This way I can simply move my kettle and controller outside if its nice out, or stay in the basement when it is not.

My kettle is one of the 16g cheapo bayou ones from amazon, it came with a crappy false bottom that is useless for keeping grains off the bottom but does a hell of a job keeping my grain bag from touching the element.

So now I have gone electric and will not look back. My 5500w BIAB setup is super easy to use and clean. It does take a bit longer to heat strike water for a 10g batch but I just use that time to crush grains, recheck my recipes, drink coffee etc. Another benefit to electric is the handles of the pot and valves do not get nuclear hot from the flames.

olie said:

I WANT to go electric, because of the fast & clean thing, but it's not clear to me that it's cheaper. Especially given California's punitive rate structure.

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Follow-up: I did some more-better math. Not sure where I went astray the first time, but electric is orders of magnitude cheaper. Yay.

I can't personally think of any reason propane is better than electric except for it generally cost far less to get set up initially and can be a lot simpler.

^that^ is pretty much the whole story right there. Electric infrastructure ain't cheap if done right (and safe)...

Cheers!

I use electric on a cheap but solid build. Those grainfather looking things are pretty sweet.

Ugh. It's a glorified coffee urn. Where's the fun?

Cheers!