Biochar Kilns

You've thinned your forest and removed hazardous fuels, now what should you do with all that material? The San Juan Islands Conservation District provides biochar kilns for rent to help landowners like you process woody biomass in a safe and environmentally friendly manner.

Senate Bill 6121 legalized the use of kilns for agricultural and silvicultural burning. Kiln burning results in fewer greenhouse gas emissions and air quality impacts than open burning and produces biochar for carbon storage and soil amendment.

Kiln Rental Requirements

Attend a Biochar Workshop

Before renting a kiln, landowners must attend a workshop put on by the San Juan Islands Conservation District. These workshops cover the burn process start to finish including choosing a site, kiln assembly, feedstock prep, loading and feeding the kiln, and quenching the biochar. Past burning experience may count toward the requirement on a case-by-case basis.
Winter 2026 workshops are currently full. Email maggie@sjicd.org to be notified when new workshop dates are announced.

Obtain a Burn Permit

Permits are required for all kiln burns in San Juan County. Silvicultural burns may be permitted through either San Juan County or the Washington Department of Natural Resources. Agricultural burns must be permitted through the Northwest Clean Air Agency.

Return the Completed User Agreement Form

After receiving confirmation of your rental reservation, please sign and return the User Agreement Form. Alternatively, you can sign and pay at the CD office at the time of pick up.

Is a Kiln Rental Right for You?

Kiln burning is just one of many ways to process woody debris and produce biochar. When deciding if a kiln is the best choice for you, consider these key points:

What is the source of feedstock?

Kilns are only permitted in Washington State for agricultural or silvicultural burns. Yard waste, milling waste, or feedstock generated from land conversion or clearing may not be burned in kilns.

What type of feedstock do you have?

Branches and small logs up to 4"in diameter are best for kiln burns. Larger logs are better suited for chipping, firewood, or left in place as habitat features.
Any type of wood can be turned into biochar, and you can add multiple species to a single burn. Different species burn at different temperatures and produce biochars with different qualities and soil benefits.

Is the feedstock dry?

Dry fuels burn cleaner and more efficiently (i.e. more biochar produced). Fuels should have less than 20% moisture for best results.
It may take between 6-8 weeks for green branches/material to dry out in dry conditions (over summer) and up to 6 months in wet conditions. Larger fuels should be cured for 6 months (over summer) to a year before burning.

How much feedstock do you have?

The Ring of Fire kiln has a total volume of 5.6 cubic yards. For an effective burn, it's recommended to have 2-3x the kiln volume. For smaller amounts of materials, open piles burning can also be used to produce biochar.

Where is the feedstock located?

Kilns are best suited for areas with vehicle access. The kiln itself weighs over 300 pounds when fully assembled. Water is needed to extinguish the kiln and preserve the biochar, a minimum 200 gallons per kiln is recommended. For sites without hose access, the District has a portable water tank available to rent with the kilns.

Benefits of Biochar

In addition to a cleaner burn, kilns produce biochar, a carbon-rich soil amendment which improves soil fertility and contributes to climate change mitigation. Biochar stores up to half the initial feedstock carbon in a highly stable form that can persist in soils for thousands of years.

Try adding biochar to:

Soils for improved crop yields, soil structure, microbial activity, and water holding capacity.
Compost for reduced nutrient loss, odors, and greenhouse gas emissions.
Manure for faster composting, less odor, and a higher nutrient compost.
Raingardens for filtering heavy metals out of stormwater.

Or spread the biochar on the forest floor, returning the carbon to the source. Earthworms, microbes, and natural weathering will incorporate the biochar over time. You can plant native species into these "char gardens" or watch as fungi and native forbs volunteer to re-establish the forest understory.