How to Recycle Charcoal Email It’s grilling and barbecuing season, and even those of us with gas grills at home tend to use charcoal for outings at the beach or park. But what do we do with charcoal ashes or leftover charcoal? If you want to reuse charcoal for grilling, follow these steps: 1. Rake cold, used charcoal to dislodge extra ash. 2. Empty the ash from the grill. 3. Add about half the amount of new charcoal that you would normally use to start the grill. 4. Light the charcoal and proceed as usual. Note: If you follow this method, you may smell food drippings burning off the old charcoal. You can wait 5-10 minutes for this process to finish before adding food to the grill. If your used or unused charcoal contains additives, you cannot reuse it for other purposes. The chemicals may include borax or lighter fluid, which are potentially dangerous. Allow ashes to cool for 48 hours, or pour water onto them and stir thoroughly to speed up the process. After they have fully cooled, either wrap the ashes in aluminum foil or place them in a small metal container, such as a coffee can, and dispose of them in an outdoor trash bin. Do not place them near anything that could catch fire. If your used charcoal is additive-free, you can use it to fertilize plants. It is alkaline and contains the nutrient potash. Avoid using it with plants that require more acidity (e.g., hydrangeas and azaleas), as well as new seedlings. If your unused charcoal is additive-free, you can use it to neutralize odors, prevent metal from rusting, or balance nutrients in potted plants, garden beds and compost piles. For more inspiration, check out this list of ideas from This Old House.