Can Natural Mulch be a House Fuel?

Garden waste can be transformed into something that keeps you warm in the winter. One can use grass clippings, leaves, and chopped up stems and twigs as mulch in the garden; these materials can also be composted for use as a natural fertilizer in the garden. Alternatively, use wood mulch to heat a house. You can use these materials to form briquettes or logs that can then be burned as firewood. Using garden waste as firewood can be a low cost, environmentally friendly way to heat your home.

Commercially manufactured briquettes and logs are typically called bio mass fuels, since they utilize natural organic materials.

They are manufactured from saw dust with added wood shavings and wood chips. They are natural and are made from recycled materials. They are produced using hydraulic presses and high heat. Also, the raw materials must be dried well before manufacturing the ‘logs.’ Thus, although the logs and briquettes are dense and have very low moisture content, they are still energy intensive to some degree. Making your own briquettes is a low energy alternative.

Other companies use waste (recycled) paper to produce briquettes to burn in a fireplace or wood stove.

You can produce your own briquettes and logs from your garden waste. Rake up leaves and store in a pile. Collect grass clippings in a pile also.

If you wish to burn as much of your garden waste as possible, you can mix wood pieces or chips with the leaves and grass. Take all your small stems and twigs from your pruning and garden waste, and chop them into short pieces that are a half inch to one inch long maximum. This is very similar to the way you would chop fire wood. You can use a hatchet and chopping block to do this, or a machete and chopping block; alternatively they can be processed through a wood chipper. If using a wood chipper, larger branches and stems can be used and reduced to wood chips.

If possible, collect lots of old newspaper. Newspaper is made from wood pulp, and burns well.

Although you can simply shape small ‘logs’ or briquettes by hand, these tend to be very small and will have a lot of water in them. This in turn means they will need much longer to dry out.

Buying or making a mold to press the recycled garden waste into will give the log or briquette a consistent shape, will express much of the moisture, and so will substantially shorten the drying time. Molds can be as simple as a length of pipe. Very simple briquettes can be made using a cloth wrapped around the garden waste material and pressed between two stones or blocks.

Molds for home use are sold under many names or descriptions including: brick maker; briquette press; log maker; wet leaf log maker; paper potter; dry paper log maker; paper log maker; newspaper briquette maker; newspaper log roller; and more. These are available online or at some hardware stores.

The trick is to soak the leaves and grass in water before trying to form logs. They will help bind the logs or briquettes together so that they don’t fall apart. Try leaving them in water for a day or two. When the leaves and/or grass are completely soaked, take some and mix in some wood chips. Try four parts leaves and grass to 1 part wood pieces.

This is where the newspaper comes in handy. Add some soaked newspaper if available — it is an excellent binder and will help the log or briquette keep its shape.

You can also include soaked cardboard in your logs and briquettes. Saw dust is a good addition.

In theory you might be able to use some types of commercial mulches, but it would probably be less expensive and less work to just buy firewood.

Generally, it is best to avoid any material that has paint, glue or chemical finishes on it. Avoid treated wood. Avoid particle board, chip board and plywood due to the chemical resins and glues that are used to bind them together. Especially avoid anything plastic, with plastic film, or anything that is potentially toxic when burned.

It is worth mentioning that leaves, grass and garden clippings are a natural source of materials for garden mulch and compost. Composting these materials produces a rich soil that an excellent natural amendment to garden soil and acts as a natural fertilizer. Using your garden waste to heat your home may eventually deplete the quality of your soil.

Thus, it may be best to limit your logs and briquettes to newspaper, cardboard, and woody stems and twigs that do not readily break down in the compost.