As professionals in tree care, the challenges of wood-chip management are nothing new. While traditional methods such as mulching and dumping have been the norm, a groundbreaking approach has been emerging – biochar production through pyrolysis – right in the heart of our cities.

Wood chips are fed into a hopper on the left, then augered up the shaft and into the pyrolysis system. All photos courtesy of the author.

In this article, we’ll delve into my recent experience as the project leader at A Plus Tree in Vallejo, California, launching one of the first advanced biochar-pyrolysis units of its kind cleared for use in an urban setting. We’ll also look at what others are doing in the biochar area and explore what it could mean for our industry.

Biochar product exiting pyrolysis unit and filling Super Sacks.

The genesis of our biochar journey
Like most endeavors, it began with a problem: too many wood chips with nowhere to go but the dumps. Like many of you, we tried to offload to other avenues – asking clients to keep them, using ChipDrop and even attempting a mulch division. However, there was still too much excess and we wanted a more innovative and sustainable approach that also could help solve a broader problem.

I’m sure you’ve heard about biochar; we knew about it, too. Biochar is a carbon-rich material created from woody biomass and used as a soil amendment. We’ve been using it in our plant-health-care programs for years. Incorporating it into our practices was a no-brainer for soil health, water retention and even pest and disease resistance. It also locks in carbon for centuries, making it a valuable tool in combating climate change. (As opposed to mulch, which releases all the carbon back into the atmosphere.)

Not that wood chips-to-biochar is a new idea, or that others weren’t already doing it. But no one we knew was doing it on a large scale within the confines of a metropolitan area. Which led us to the thought, “How hard could it be?”

And with those naively ambitious words, in 2019 I got the green light from our CEO, Cyrus DeVere, to embark on a pursuit to bring this idea to reality. Little did we know it would take four years and a myriad of seemingly never-ending obstacles to accomplish.

Fueling the vision
Visions don’t fund themselves, no matter how great they are. We knew this project was going to cost a lot of money, money we didn’t have. So I googled all the biochar experts in California and found Raymond Baltar, someone whose vision matched ours perfectly. Also, he happened to live nearby and was enthusiastic about helping us figure it all out.

We welcomed Baltar as our biochar specialist and partnered with his organization, the Sonoma Ecology Center, a nonprofit with significant experience in managing large grants. Together, we secured a state grant from CalFIRE’s Urban and Community Forestry program, which was instrumental in getting this project off the ground. The goal was to prove the model that woody waste materials produced by the urban tree care industry can successfully be upcycled into biochar.

The funding not only covered equipment and site preparation, it also covered the costs for permitting, air-quality reports, tree planting and community outreach. We were expected to invest some of our own money as well, matching about 20% of the awarded amount.

A year after grant submission, we were awarded $1.2 million. It was more than just dollars; it was an endorsement of what this could become.

Sarah Gaskin, with A Plus Tree CEO Cyrus DeVere, holding up her biochar vision board she made in 2019 and what initiated the whole project!

Choosing technology wisely
When it came to choosing the right pyrolysis technology, we needed something that could handle urban realities: a compact footprint, low emissions and scalability. After researching multiple systems, we landed on a unit from ARTi, an international company that develops complete, automated and modular biochar production systems. This unit checked all the boxes – within our price range, scalable, fully containerized, mobile, emissions controlled and capable of processing urban wood waste with minimal preprocessing.

With this unit, we felt confident we could prove our model at a practical scale, meet our California air-district requirements and demonstrate that clean biochar production can happen within city limits. The unit requires only a small amount of natural gas to start up, but once it’s running, it sustains itself by recirculating its own gases. Emissions are remarkably low, making it a truly clean and viable solution for cities looking to manage wood waste sustainably.

Navigating the regulatory landscape
The permitting process to launching our pyrolysis unit was far from straightforward and presented hurdle after hurdle, especially in the heart of the Bay Area in Northern California. As with most bureaucratic agencies, new ideas are often met with hesitancy as they grapple with unfamiliar concepts and fear deviating from the norm.

We encountered significant regulatory challenges with the Bay Area Air Quality Management Board (BAAQMD) and then a major setback when the U.S. Environmental Protection Agency (EPA) classified the ARTi unit as a “solid waste incinerator.” This classification effectively deemed its operation illegal in urban environments, since wood chips were viewed as municipal solid waste (MSW).

In August 2024, after another 10 months of meetings, appeals and detailed letters explaining the technology, the EPA reversed its decision, exempting our unit from that classification.

This was a huge win, not just for us, but for the broader biochar industry, potentially paving the way for others to follow.

Finally up and running, this unit is now producing two tons of biochar daily from 10 tons of wood chips.

The power of partnerships
The project wouldn’t have been possible without the right partners. Sonoma Ecology Center, our nonprofit partner, was instrumental in securing and administering the grant. ARTi, our technology partner, collaborated closely with us to adapt their pyrolysis unit specifically for the arborist wood chips generated in urban tree care. Finally, Napa Recycling & Compost Services provided us with something truly rare in urban settings: ample space. Their existing site not only offered the land to operate, but also already held some of the necessary zoning and permits.

We could never have accomplished this alone; such collaborations are truly what make innovative projects possible.

Emissions testing being conducted on our biochar system by Best Environmental.

Insights from industry peers
In a conversation with Brian Borkowicz from Davey Tree, he shared valuable insights into their biochar operations (see “The Business of Biochar by Tamsin Venn, TCI Magazine, June 2024). When asked about the permitting process, Borkowicz mentioned, “It was relatively painless only because we went right to the [city] with what we were going to attempt to do right out of the gate.” Regarding EPA involvement, he emphasized the importance of framing the project correctly. “The thing that we have learned is that you never want to tell them it’s waste. It’s recycling … Because as soon as you tell them two things, compost or waste, that’s a problem.”

He also commented on operational challenges. “We thought the automation process was going to be a little easier to get the thing running 24/7 without having it be [staffed], and we found out that you can’t really do that.”

Future considerations and a call to action
We deem our project a success. The financial model is still yet to be proven. But the “success” here is diverting some wood-chip waste from the landfill to a biochar unit operating within the same local area that the wood chips are being generated, specifically by urban tree companies. This as opposed to having transportation costs and the greenhouse gas emissions you would have in trucking to a facility elsewhere.

OK, let’s be real; most tree care companies aren’t going to buy a massive pyrolysis unit. The sticker shock alone is enough, not to mention the permitting nightmares and the sheer headache of running the thing. But that doesn’t mean smaller companies can’t get in on the biochar revolution.

Opening day ribbon-cutting ceremony on May 3, 2025. Pictured, from left, are Evan Jones, regional urban forester, CalFIRE; Cyrus DeVere, CEO, A Plus Tree; Raymond Baltar, biochar program manager, Sonoma Ecology Center; Sarah Gaskin; and Will Kelley, manager, Napa Recycling.

One solid option is to look for partnerships with local recycling centers. These places often already have their permits sorted and plenty of room to produce biochar. By working together, tree care companies can use existing facilities and share the operational expenses. It’s a smart move that benefits everyone.

Getting our urban biochar unit off the ground was tough, but honestly, it’s been just as rewarding. We hope our story inspires other tree care companies to find new ways to handle all that tree debris.

Ideally, everyone would shift toward using biochar instead of just mulch. Tree care companies and arborists need to collaborate to promote the use of biochar in urban soils. Our urban soils are in such poor condition and desperately require amendments such as biochar and compost to ensure our trees, shrubs and turf thrive.

The path we’ve taken at A Plus Tree demonstrates that with determination, collaboration and innovation, it’s possible to turn urban wood waste into a valuable resource. We encourage other tree care companies to consider biochar as a sustainable solution to debris management. Whether through investing in pyrolysis units or forming strategic partnerships, there’s a role for everyone on this transformative journey.

Sarah Gaskin is vice president of strategic initiatives with A Plus Tree LLC, a 22-year TCIA member company based in Vallejo, Calif. Gaskin spearheaded the biochar project and led it with Raymond Baltar with Sonoma Ecology Center. The project was funded by CalFire and now operates at the Napa Recycling & Compost facility.