Is biochar an effective carbon sequestration technique?

August 1, 2023

Heat-trapping carbon dioxide (CO2) in the atmosphere has reached levels not seen in nearly two million years. And, like when you turn up the thermostat in your house, our home, Earth, is rapidly growing too hot. June of this year was the hottest month on record. July will likely top it.

There may be a way, however, of permanently storing CO2 in the ground, preventing it from entering the atmosphere. It’s called biochar.

Too often, tree waste, from logging and other sources, simply decays in place or, worse, is burned. Either way it emits CO2, methane, and other toxic gases. 

Biochar is a charcoal-like substance created from burning tree waste, often called slash, in a special incinerator. It is porous and helps to retain moisture and nutrients in the soil. And it can sequester carbon for up to a thousand years. Biochar also helps prevent runoff, thereby enhancing the growth of crops, plants, and trees. It may also reduce soil compaction, further improving productivity. 

Jonas Parker holds biochar from the 2020 Holiday Farm fire in Oregon.

The biochar production process will also benefit forest and land managers who need to dispose of slash from logging and trimming operations. By eliminating slash piles it can also help prevent wildfires.

A field of slash from the September 2020 Holiday Farm Fire in Oregon.  The fire, located along the McKenzie River, is a one of the largest in Oregon history burning more than 173,000 acres.  The U.S. Bureau of Land Management is clearing the slash and other roadside hazards.

Biochar is not some exotic substance that needs special handling. It can be easily applied to the soil using conventional farming equipment, or even spread by hand.

Biochar can be easily applied to the soil using conventional farming equipment.

The special incinerator referred to above, called a pyrolizer, circulates air at high speed around the burning slash. This creates high temperatures with low oxygen levels, reducing smoke while preventing the slash from being burned to ash. Many commercial pyrolizers are about the size of a garbage dumpster and can be towed behind a truck to the slash site. Larger pyrolizers, up to thirty feet in length, are made for larger scale, permanent and semi-permanent installations.

The US Forest Service and Air Burners Inc. demonstrate the CharBoss pyrolizer and biochar production process. Oregon, October 2020.

Jonas Parker, a soil scientist from the U.S. Bureau of Land Management and his team are investigating the benefits of applying biochar to the soil. Starting this summer, and over the next several years, they will be assessing soil productivity, water retention, seedling survivability and growth rates as well as the rate of invasive weed growth. Several test sites have been set up to monitor the benefits of different application rates and soil conditions.

Jonas Parker describes biochar and it’s benefits.

Companies are already trying to make a financial go of the process. Oregon Biochar Solutions, for one, produces biochar on a commercial scale. The company burns up to 200,000 tons of bone-dry wood waste per year, producing up to 4,000 tons of biochar while avoiding 8,000 tons of CO2 emissions. Their innovation does not stop there. Excess heat from the production process can produce enough electricity for up to 26,000 homes per year.

Ultimately, professionals will need to study the cost and benefits of biochar, including an end-to-end analysis of the emissions created by the process, comparing it to natural decay or field burns. But Parker and team are making a great start on what looks to be an effective way to sequester carbon for up to a thousand years.

To learn more:

Jonas Parker with the U.S. Bureau of Land Management can be reached at j1parker@blm.gov.

Oregon Biochar Solutions produces commercial and residential biochar.

AirBurners Inc. manufactures the CharBoss and many other pyrolizers.