You can make your own charcoal. If you are burning off brush or other stuff anyway, this is an easy way to stock it up.
1. Get a 55 gallon metal drum with a fireproof lid.
2. Choose good split & seasoned wood – cherry, oak, or hickory all work well. Chop into 3-4 inch pieces.
3. Pack drum tightly with wood. Put lid on well enough to stay in place, but don’t make it airtight.
4. Light a bonfire around the drum, adding wood as needed around and on top of drum to keep it burning 3 to 5 hours.
5. Let fire completely burn out and cool down before approaching drum.
6. When you open the lid, you’ll see a fresh batch of pure lump coal.