Coffee grounds are worth their weight in gold! Okay, maybe that’s a bit of an exaggeration, but those leftovers from your daily cuppa (or potta) joe are more valuable than you might think—certainly more than just a trip to the trash bin.
While composting coffee grounds is always a great option, there’s another fantastic functional way to use those leftover grounds that will also enhance your winter nights or chilly mornings: coffee ground fire logs.
Today, we’ll go through the easy-peasy process of creating these aromatic wonders, transforming what some might see as waste into a source of fragrant warmth and ambiance.
Let the repurposing begin!
What You’ll Need
Leftover coffee grounds: Yes, I know—duh. You’ll need about five times more grounds than you will binder material, so I’d save up at least five cups of grounds before making your first fire log.
Sawdust, old newspapers, or used cooking oil: Any of these will serve as the binder for our logs. We have more sawdust these days than the other options, so that’s what we use.
A bucket, bin, or large bowl for mixing the ingredients
A mold to shape your fire logs, which can be tubes, discs, blocks, etc.
In keeping with our reuse and repurpose theme, here are some ideas for molds:
Cake pan: You might want to puncture holes in the bottom to let the moisture out.
PVC: Cut a PVC pipe to the desired length and drill some holes near the bottom to press out the liquid. You'll need to cap or cover one end so you can pack the fillings in there.
Cardboard boxes: Small cardboard boxes can be used as molds or cut larger ones down to the desired size.
Plastic containers: Old, cleaned plastic containers, like from yogurt or sour cream, can also be used as molds.
Easy Coffee Ground Fire Log Step-by-Steps
1. Drink your brew and save those coffee grounds
You can also check with your local coffee shops to see if they want you to do a pickup. Store the grounds in a container in your fridge to prevent mold growth until you have enough for a log. We keep ours in a covered five-gallon bucket in a cool place and have no problem with mold.
An important note: Dry the coffee grounds (we use a tray) before placing them in a bucket or other container for storage to prevent molding.
2. Collect Your Binder
Save sawdust, old newspaper, or even used cooking oil.
3. Prepare Your Binder
Once you have enough grounds and binder, prep your binder of choice
Sawdust can be used as a binder by mixing it with a small amount of water to form a paste. The paste can then be mixed with the coffee grounds and shaped into logs.
If you use newspaper, you can use it as a binder by soaking it in water for a few hours—a few days is even better—before mixing it with the coffee grounds. The water will help soften the newspaper and make it easier to mix.
Cooking oil can be used as a binder, too, although we haven’t tried this ourselves (yet). Straining the oil isn’t necessary, but it’s a good idea to remove any large food particles or debris that might be present. You can use a fine mesh strainer or cheesecloth to do this. Apparently, using used cooking oil as a binder shouldn’t make the fire logs smell strange, but if the oil is rancid or has a strong odor, it’s best not to use it (to state the obvious).
4. Mix Your Ingredients
In your bucket or large bowl, combine the coffee grounds and binder. You’ll want a ratio of about 1 part binder to 5 parts coffee grounds.
5. Form Your Log Once your mixture is well combined, pack it tightly into your chosen mold and press out as much liquid as possible. The tighter you pack it, the better your log will hold together.
To ensure the logs come out of the mold easily, line the inside with a plastic bag or wax paper. If you’re using a PVC pipe, you can lightly grease the inside with cooking oil to prevent the log from sticking.
6. Let It Dry
This is the hardest part—waiting! You’ll need to let the log dry completely before you can use it. This can take anywhere from a few days to a week, depending on the size of the log and the humidity in your area. If the log is still damp, it may break apart when you try to remove it from the mold.
7. Remove the Log from the Mold If you’re using a cake pan or plastic container, turn it upside down and gently tap until the log comes out. If you’re using a PVC pipe, push the log out. If the log is stuck, you can carefully use a butter knife or similar tool to loosen the edges and then try again.
8. Enjoy Your Fire Log In your fireplace or stove, put down some crumpled paper or kindling (or both). Then, add your coffee ground fire log on top of the kindling. You can add two or three of the logs, but no more than that because they can make some serious heat. Light the fire using matches or a lighter, and then leave the log for 15 minutes while they ignite.
Final Words on Fueling Your Fire with Leftover Coffee Grounds
Did you hit the mother load of used coffee grounds and make a whole bunch of fire logs? If so, store those extras in a dry, covered area so they don’t get wet and fall apart. If you don’t have a shed, stack the logs on an old pallet or anything else to keep them off the ground and cover them with a tarp. We store some in a plastic tote bin.
As for flue build-up—something I wondered about—coffee-ground logs don’t produce as much soot build-up as traditional wood logs. That said, no matter what you burn, it’s always a good idea to regularly inspect and clean your flue to ensure the safe operation of your fireplace or wood stove.
Enjoy those coffee-scented flames!
Looking for other ways to reuse and repurpose spent coffee grounds? Here's a list with 11 other ideas.
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