City testing biochar to reduce waste

Alexis Barker
NLJ Reporter
 
The city is testing a new program that turns wooded waste collected at the city compost site into biochar instead of grinding the waste into a wood chip product. 
On April 1, Travis Peterson, city arborist, told the Newcastle City Council that he had recently tested a process for turning the waste into biochar and that it was cheaper. According to Peterson, the city realized an annual net gain of $30,101.70.
Biochar is a charcoal used as a valuable soil amendment, according to biochar-international.org. 
“This 2,000 year-old practice converts agricultural waste into a soil enhancer that can hold carbon, boost food security and increase soil biodiversity and discourage deforestation. The process creates a fine-grained, highly porous charcoal that helps soil retain nutrients and water,” the website says. 
Peterson said he has been kicking around the idea of turning collected waste at the compost site into biochar
but had not acted on the idea until now.
He said that he burned down the waste in two different “pit kilns” to provide a safe and clean controlled batch burn. 
“I burned in one on one day and one on the second day while I worked the first pile,” Peterson said, calling it an efficient process. 
The process uses a flame cap to limit the oxygen, Peterson said, allowing for temperature control and control of emissions. The fire is put out before the waste is turned to ash, leaving it in a coal-like stage. 
“We used truckloads of snow that we gathered in neighborhoods where we don’t use a lot of chemical on the roads, so it’s nice clean snow. We took the snow to the site and used it to quench the fire at the coal stage,” Peterson said. “It took about three dump-truck loads.” 
The biochar conversion limits the volume of product the city has to deal with and saves the city money, Peterson said. 
According to Peterson, the wooded waste collected in 2017 was ground by contracting a company from Montana and total cost to the city was $13,591. The volume of the chips created was 675 cubic yards, enough to fill 18 school buses. 
Turning the 2018 collected waste into biochar, according to Peterson, cost the city a total of $1,378.30 and created 67 cubic yards of volume, enough to fill nearly two school buses. 
“The value of the biochar from the 2019 pilot project is $17,889 at $267 a cubic yard,” Peterson said. “The annual net gain for the City of Newcastle is $30,101.70.” 
Not only is there a financial benefit to the project, Peterson said, but there are environmental benefits as well, including long-term carbon sequestration; reclamation and remediation, such as binding toxins and preventing leaching. It also increases the ability for soils to retain and sustain moisture, nutrients and microbial associations. 
For the time being, Peterson said he plans to mix the biochar with the compost product used by the city while he also performs germination tests with the product. He said that the biochar product will also help to alleviate some smell issues at the compost site during the summer months. 
Initially, Peterson said, he will only be using the product for city projects while he
learns more about the process. He said that the state of Wyoming allows biochar use in agriculture. 
City Engineer Mike Moore added that the compost pile was started several years ago to alleviate some of the impact on the landfill. Peterson reported that the average annual brush volume diverted from the landfill, from 2013 to 2018 is 4,410 cubic yards per year, or approximately 119 school buses full.