Recycling charcoal

[Paul G.]

I've used a WSM for more than 15 yrs, but up until recently was not aware of TVWB. Of course it is GREAT. Previously I've used the Weber method of lighting, but have began using the Minon Method for long cooks and the standard for shorter ones. I don't like to waste charcaol. While $s are not really a consideration, I just have a problem with lots of left over and unused fuel. I've saved and reused charcoal, but I've never felt it did quite as well as all new charcoal. Also, I've seen comments about buring the old charcoal first such as in the chimmney rather than putting it in with the new coal. My question is how to calculate the amount of new fuel to use taking into consideration the used fuel you're using. I don't think it would make sense to simply use it as if it were new. In other words don't add any more additional charcaol than you would based on the volume of the chimmney as a measuring cup. Has anyone experimented and come up with a good formula so that you're able to use the old charcoal, but still have enough new so that you get a similiar burn rate and equal results as if you had used all new charcoal?

Thanks, PRG

 

[Guest]

Paul,

Here is my 2 cents to keep this at the top of the list of threads in hopes that someone with more knowledge can enlighten us.

My experience with reused coals on grills (not WSM)is that while you can get a similar initial temperature, the temperature drops much faster, so your "similar burn rate" request won't be realized. On the grill I keep my vents wide open, so my temperature is fuel limited rather than air limited, so the difference in burn rate may not be as great on the WSM.

Also the lump charcoal fans at the BGE and Primo forums constantly have to deal with different size chunks of coal, and I recall reading some advise to sort your lump by size and stack it on the firepit in a certain order. You might search through their forums for some ideas.

Good Luck!

 

[Paul G.]

Mark

Thanks for the response. I was begining to think the question was either so easy to answer or so difficult to answer that it did not warrant a reply.

If I don't hear anything further, I think I'll only reduce the new charcoal slightly as a result of using what will probably amount to about 1/2 chimmney of old.

I suspect this is yet another example of trying to be a little too technical. As Emeril says, "It ain't brain surgery"! I have learned you can make this stuff about as difficult as you want.

PRG

 

[Guest]

Paul,

This falls in the category of using math to calculate how long it takes to get meat to a particular temperature. Harold McGee's "Curious Cook" took that problem on in a chapter.

I think that with unlimited air-flow charcoal puts out heat proportional to the surface area, but that it burns at a slow linear rate inward. This means that the surface area reduces by small percentages early in the burn (say the first hour of a fresh brick) but after the bricks get small the surface area reduces very fast (proportional to the radius squared on a sphere, for instance). If you can slow down the burn rate (by restricting air-flow) you should have less of a problem than I have on a wide-open grill.

Ash buildup could slow down the burn rate also (making the temps drop that much faster with old charcoal). But I played with an Excel spreadsheet modelling fresh bricks as 2 inch spheres and making up some constants, and I've come pretty close to what I see on my grill, so I think the ash buildup is secondary to the surface area problem.

 

[Paul G.]

Mark

Thanks for the simple explanation, but I was really looking for something with a little more depth. You managed to give a country lawyer a real headache !

PRG

 

[Guest]

Paul,

Yeah, you can probably get a hint of my engineering background in my answer. Looking back through the ceramic cooker forums, I notice that the big concern is that the small stuff will eventually fall down and block the airflow from underneath on a long cook. So they advise sorting their lump charcoal so as to have the small stuff on top. See http://www.nakedwhiz.com/elder.htm as a good writeup for this. The description burns top down, which is sort of Minion-like.

This is probably a more practical answer, even for a WSM. I have more trouble on my grill when I want to cook something like whole sweet potatoes at 450 deg for over an hour, so I notice a severe loss of heat by the end of the hour if I don't have enough fresh bricks. Falling ash doesn't block airflow in my Smokey Joe Platinum, which gets it's air from the sides by the handle.

Good Luck!

Mark