Blazin’ Joe: Brewing a Sustainable Startup
Maddie Cataldo and Maya Nefs with their Blazin' Joe firelogs
In 2019, when freshman Maddie Cataldo (Mgmt’23) showed up to her first CU Boulder club hockey practice, she didn’t know anyone. But a spontaneous locker room conversation about skydiving ignited a friendship.
Maya Nefs (Mgmt’23), then a sophomore and fellow Leeds School of Business student, didn’t hesitate: “What are you doing next week? Let’s go.”
They went, tumbling into the air over Longmont, Colorado.
Years later, that same adventurous spirit fuels their company, Blazin’ Joe, which transforms coffee waste into sustainable firewood alternatives. Their business started in a college oven and now operates out of Nefs’ garage in Golden, Colorado.
Cataldo and Nefs’ journey as business partners is rooted in their shared CU experiences: business classes, a love for the outdoors and hockey.
“Being teammates really helped us work together,” Cataldo said. “We’re both super competitive, and there’s a level of bluntness that’s good and healthy to have. You could yell at each other on the ice and grab a beer right after.”
They’re also candid about the challenges of going into business together.
“I wouldn’t say it’s super easy going into business with a close friend,” Cataldo said. “We have a contract that tells us we need to spend a certain number of hours not talking about Blazin’ Joe, but just hanging out.”
Nefs added: “We’ll go play tennis or grab a happy hour drink. One of the most important aspects of the business is keeping our friendship healthy.”
It’s a priority that pays off personally and professionally.
“I wouldn’t be doing this with anyone else,” Nefs said. “Maddie has such a positive attitude, and I definitely find myself aspiring to carry the same positivity.”
The idea for Blazin’ Joe began in Cataldo’s senior capstone course, the New Venture Launch, taught through the business school’s Deming Center for Entrepreneurship. Her class project pitch centered on a fire log made from used coffee grounds, which was inspired by her father’s entrepreneurial research in biofuels.
Blazin' Joe firelogs
“I remember using the oven in my college house 24/7 to dry coffee grounds,” said Cataldo. “My roommates were awesome because the house always smelled like coffee — even our clothes.”
Cataldo’s professor, Brad Werner, saw something unique in her.
“She wasn’t just presenting a business idea — she was sharing something she truly believed in,” Werner said. “I look for students who demonstrate genuine customer obsession — not just talking about their product, but showing they truly understand their customers’ pain points.”
Cataldo’s team won the pitch at the end of the capstone class, impressing Werner with their compelling presentation, and walking away with first-place recognition.
After graduation, Cataldo tried running the business alone until Nefs stepped in.
“She was thinking of putting it on pause,” Nefs said. “I told her, ‘Don’t do that. I’ll work on it with you.’ The company had so much potential, and people were buying the product; it just needed two people behind it.”
Today, Blazin’ Joe makes fire logs and fire starters from coffee chaff — the light, flaky skin of the coffee bean discarded during roasting. It burns clean, hot and efficiently, without the toxic chemicals found in traditional fire-related products.
“We started out using coffee grounds,” Cataldo said, “but realized drying them used too much energy. Chaff was the game-changer: it’s dry, burns well and it’s a huge waste stream in the industry.”
They now collect chaff from local Colorado roasters like Sweet Bloom Coffee, Otis Craft Collective and Copper Door Coffee Roasters. They use about four pounds of chaff per log, Cataldo said, and grind it down and press it to shape in Nefs’ garage.
“I’m grateful for the setup,” Nefs said. “We’re not paying rent on a space, and for a small startup, that’s critical. We’re growing sustainably, on our own terms.”
Since launching into retail in January, Blazin’ Joe has found traction in farmers markets and local stores like McGuckin Hardware and Lucky’s Market. In May, they also won the Next Cycle Colorado Pitch, which supports companies repurposing waste streams in Colorado.
Cataldo is eager to grow the business more.
“Our ultimate goal is to work towards making the coffee industry circular,” she said. “We’d love to partner with bigger roasters on a larger scale and repurpose as much waste as possible.”
Photos courtesy Graham Gardner (Sparrow Creative)