Change from bottling to keg.

Carbonating with sugar instead of force carbonating saves CO2. But it also increases the ABV of the beer (just like bottling with sugar). I use sugar to carbonate in kegs when cloning beers that are normally bottle conditioned and that get a significant amount of ABV from the sugar.

That depends on the beer style, the state your beer was in when you packaged it, and your preferences. Beer ages over time (faster at higher temperatures), whether it's in a bottle or in a keg. That aging includes both maturation (flavor improvements) and staling (flavor deterioration). Unfortunately, you can't have one without the other, though you can limit/slow down staling by keeping O2 out of your beer.

 

If keg-priming you might have difficulty sealing your lid. Remember, the lid works by having pressure applied from the inside to compress the o-ring. At zero pressure (start of keg-priming) you aren't guaranteed to have a seal. When I rinse my tanks I invert them and all but one does not leak . . . even the good ones may have trouble holding pressure when it's at a very low level (first molecules of CO2). I've even tested the good ones with low pressure (<2psi ) and sealing the lid can be a problem.

You will have additional trub when refermenting in a keg. Expect some solids to drop out with force carb'ing, expect more if refermenting. The work around is a shortened dip tube or just pour off more beer.

With force carb'ing it's easy to change carb level if you don't like what you started with. Just adjust some valves and level can be modified. For traditional bottle-carb'ed beers I stick to bottles. Overall it's probably easier to cut down on oxygen-pollution with kegs. In addition to force carb'ing, a tank of CO2 in the brewhouse is handy for lots of other applications. Oh yeah, you might want to hang around Home Bar, we talk about pressures & valves & leaks and other cool stuff.

 

https://www.beeradvocate.com/community/forums/home-bar.43/

It depends. If you add pressure the CO2 will dissolve into the beer. With a small headspace and 5 gals of beer this will happen pretty quickly (less than a day) so you're back where you started.

Some of my lids seem to seal at low pressure . . . but some definitely leak until the pressure is cranked up. The over-center lever compresses the o-ring, some are stronger than others with a new keg probably superior to used. It's also possible to use an oversized o-ring to fight the problem (I have one keg so equipped).

Not saying it won't work as I've never tried it, but would be ready for it to fight you. Maybe Vikeman can chime in with his method.

 

As @PortLargo mentioned, if you just pressurize the headspace once, the CO2 will dissolve into the beer until it reaches equilibrium, leaving not much pressure in the headspace. But you can keep it on the CO2 at a constant 2-3 PSI (enough to keep the lid sealed) for a couple days, until refermentation CO2 can take over. At room temperature, the impact on your final CO2 level will be very small.

 

most of my lids are pretty solid at low pressure - just locking it down seems to work most of the time.
I do use sugar to prime my beer even in keg - mostly saving |CO2 - though this is residual habit from not having a tank for a long time.
That said, the past few times I've kegged, I'll batch prime as usual (about half the sugar as I would use if I was bottling) but give it a shot of CO2 then release. I'll do this a few times to flush out as much atmospheric air as I can and leave not much oxygen. |I don;t know how much difference this actually makes, but I feel better doing it.

 

One thing about sugar priming in the keg... assuming you're kegging 5 gallons, you should use about the same amount of priming sugar as you would for bottles. The internet is full of advice to use 1/2 as much, or 2/3 as much, or pretty much any fraction you can imagine. I imagine this got started due to someone eyeballing beer and headspace volumes for bottles and kegs without actually measuring.

Doug293cz of the HBT forum has measured corny keg volumes and found them to be between 5.3 and 5.35 gallons. So, for 5 gallons of beer that's:

5.3 gallon keg: 94% beer, 6% headspace
5.35 gallon keg: 93% beer, 7% headspace

He also measured bottles, and I confirmed them (actually I didn't know his results beforehand) using standard LHBS "12 ounce" bottles. I measured them to hold 12.81 fluid ounces full. I then displaced the the volume with a standard (and closed) bottling wand, and 12.24 fluid ounces remained. (Measurements were done with water, by weight, then converted to volume.) So, for a bottle, we get:

"12" (12.81) ounce bottle: 96% beer, 4% headspace

You can work through the non-trivial math involving residual fermentation CO2, volumes, pressures, and Henry's law, but having done it, I can say that it's not worth it. The answer to how much priming sugar to use for a keg compared to bottling is very close to 100% (slightly more than 100%).

Just to add an empirical data point, when I sugar carb in kegs (using the same amount of sugar as I would have for a target CO2 volume in bottles), I keep a pressure gauge on the gas post to monitor progress. When it stops, it's always very close to the PSI value that corresponds to the PSI value from the keg force carbonation equilibrium charts for the CO2 volumes target and the temperature.

Note: Again, this assumes a 5 gallon batch. If kegging less than 5 gallons in the corny keg, (i.e. the ratio between headspace and beer changes significantly), you actually need more priming sugar (proportionally, i.e. sugar to beer volume ratio) because the headspace gets a larger proportion of the CO2 produced.

One might wonder how people have got by with priming with half (or whatever) as much sugar in kegs. IMO, two reasons...
1) Using half as much sugar will actually yield more than half as much total CO2, because the residual CO2 from fermentation is additive (and a constant in this case).
2) Once the keg is believed to be "fully" carbonated (with not enough sugar), it's put on CO2 to serve, which finishes the job.

 

Is the "more priming sugar (proportionally)" significant enough to merit inclusion of additional user-entered variables on the BrewCipher carbonation tab, e.g. "Kegging, (priming sugar)"?

 

To answer the question of advantages of sugar priming vs. force carbing, force carbing is hands down the better choice.

Except as noted by @VikeMan when trying to clone a beer that is bottle primed there is no good reason I can think of to sugar prime a keg. CO2 gas is one of the least expensive things in our brewing world. Use it generously.
(I mean, if you can drop $500 or more on kegs, regulators, temperature controllers etc. not to mention hops, yeast and grain then the $20 bottle of CO2 does not seem like so much of a concern to me).

Some people claim the CO2 from sugar priming is finer, smoother or different than the CO2 from a bottle but those people...

Cheers

 

O=C=O

 

Maybe. But right now there's a standalone calculator on my club's web site that can tell you how much sugar (as a percent of bottling sugar) to use in a keg, given bottle specs, keg specs, batch size, desired volumes, etc.

Bottles to Keg Sugar Adjustment Calculator (.XLS) at
http://sonsofalchemy.org/library/

 

Perhaps I should roll my eyes back atcha!?!

I can't comment to keg conditioning but for my homebrewed beers that I carbonate via bottle conditioning there is indeed a difference in mouthfeel as compared to commercial beers that are carbonated via CO2. My bottle conditioned beers (and commercially produced bottle conditioned beers) have a different mouthfeel (softer, rounder, etc.) that is an improvement for my palate. For folks who do not highly value this mouthfeel aspect then carbonated via CO2 tanks is likely just as good.

Perhaps you personally do not perceive a difference in this regard but I most certainly do.

Cheers!

 

Thanks for the link. Running a quick look-see…
Common Data values used in both BrewCipher (BC) and the B2K stand alone calculator:
2.5 vols CO2, 68° F, (Final Temp 40° for kegging, N/A for bottling in BC)

Keg data (total keg volume 680 oz):
512 – volume of beer in kegs (4-gallons)
168 – volume of headspace in keg

BC calculated 3.9 oz corn sugar to bottle prime 4-gallons
B2K returned 129%, which would be 5.0 oz corn sugar
By comparison, BC returns 4.9 oz corn sugar for a 5-gallon bottled batch

I’m not disputing the results; don’t have the smarts.
As one with less than adequate comprehension of Henry's Law, et.al., it was quite surprising and counterintuitive for me to see that it would take:
1) more sugar (0.1 oz) to carb a 4-gallon batch kegged than a 5-gallon batch bottled, and
2) almost 30% more to carb 4-gallons in a keg vs. bottles
(assuming my data entry was correct. )

 

I suspect you may be thinking in terms of total CO2 (which the drinker really doesn't care about), rather than the concentration of CO2 in the beer itself (which is the important thing). Henry tells us that the CO2 dissolved in the beer is proportional to the CO2's pressure in the headspace. Think about 4 gallons of beer in the corny, with that (extra) gallon of headspace. That headspace has a lot of room to take on extra CO2 before equilibrium with the beer is reached. And, don't forget that it's not just the "new" CO2 from sugar that has to reach that equilibrium... even more of the "old" CO2 left over from fermentation is also lost to the headspace, so the sugar qty has to also make up for that. Thinking about any almost any of this linearly leads to sorrow.

A real life example a lot of us can relate to... Have you ever brought a growler of beer home, drank half, and put then put the growler in the fridge for a couple days? What happens when you open the growler again? There's still a satisfying "pop" when you open it, but the beer is fairly flat. It's not because "growlers are bad at holding pressure." It's because a lot of the CO2 in what was left of the beer migrated to the headspace, which (after drinking half the growler) had room (and lower partial pressure) to accept it before equilibrium was reached.

Now think about just leaving that growler open for a day or so. It degasses, because the partial pressure of CO2 in the atmosphere is much lower than the what's needed to keep much CO2 in the beer. And you end of with ~ 1 volume (give or take, depending on temperature) left in the beer. You could wait forever (if you could magically keep the beer from evaporating) and not lose that last bit of CO2. Think of the atmosphere as a very large headspace.

 

Thanks, that was helpful.

Ye are quite perceptive.

 

I love this visual description as much as the first time, so what the hell

 

Sorrow indeed, here's what happened to the last guy who used linear logic on his vacuum:

 

Reducing the priming sugar is actually sound advice and it goes directly to the issue of the need to seal the keg. Except in rare cases, a corney keg lid needs pressure to seal properly. That's inherent to the design. And so we add pressure up front.

The problem this creates is that the beer will happily lap up that pressure in addition to the CO2 created by the priming sugar. The inevitable result is that, if you use the same amount of sugar, absent a spunding valve, you're virtually guaranteed to have overcarbed beer.

The 'experts' who have a magic formula for determining how much to reduce the priming sugar simply note the perfectly carbonated beer that results as validation of their recommendation when, in reality, it's irrelevant. You can reduce it to zero and get identical results (notwithstanding the big bubbles/little bubbles thing, but that's another discussion).