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  • Writer's pictureAngina Herrmann

Thomas Käslin: “We want to make every cup of coffee environmentally positive”

Coffee brands improve their supply chain sustainability, farmers reap higher yields with lower costs, and consumers enjoy their brew with a good conscience. All this can happen with the biochar produced by Swiss-Colombian startup Cotierra, says the company’s CEO and Co-Founder, Thomas Käslin.

Profile photo of Cotierra CEO and Co-Founder Thomas Käslin
Cotierra CEO and Co-Founder Thomas Käslin

It’s the circle of carbon-based life: as plants grow, they capture carbon dioxide from the atmosphere. When plants die and decay, the carbon goes back into the atmosphere – even faster if the plants are burned. But what if we could catch this carbon instead and slow down global warming?

Cotierra is a Swiss startup that promises to do just that. The company has developed a way to turn biomass into biochar, which can stabilize carbon within the soil for centuries. CEO and Co-Founder Thomas Käslin walks us through the process:

  1. Coffee farmers collect pruned branches and other woody residue for Cotierra.

  2. The company brings its proprietary and mobile reactors to the farm and heats this biomass until it becomes biochar.

  3. The farmers take back the biochar and mix it into their soil.

In addition to stopping the carbon cycle, biochar helps the climate by improving soil health. Thomas explains that tropical soils are not good at retaining nutrients, especially after decades of intensive farming, so farmers need more fertilizers to grow their crops. The tropics are also known for their heavy rains, and these rains wash off a lot of the nutrients, which then need to be replenished. All this adds up to a lot of fertilizers used to grow crops in the tropics – which is where most of our coffee beans come from.

However, when coffee farmers mix biochar into their soil, the mixture behaves like a sponge for nutrients and water. Suddenly a smaller amount of fertilizer can sustain much more plant life: Thomas notes that biochar allows coffee farmers to reduce their fertilizer usage by at least 30%. As fertilizers are responsible for 5% of all global carbon emissions, this makes a difference. Soil improved with biochar also results in higher yields. The overall effect brings a typical smallholder coffee farmer 30% higher profit margins, Thomas estimates.

“We want to have 10,000 biochar reactors operating by 2028”

Two coffee farmers applying biochar into their field soil
Biochar application for field trials

Turning biomass into biochar is similar to making charcoal from wood, a process people have used for centuries. Cotierra adds a modern twist by offering an app with detailed analytics to monitor the process. Customers receive precise information about the amount of biochar produced and its climate impact, which is essential for Cotierra's business.

On the most basic level, Cotierra offers a hardware product: the biochar reactor. Yet the company’s business model is more complex. The users are typically smallholder farmers, but the primary customers are large coffee brands improving the sustainability of their supply chain. These customers buy verified emission reductions and removals, measured in tons of CO2 removed. This is why Cotierra needs reliable and detailed monitoring of the process.

Reducing and preventing carbon emissions within a company’s own supply chain is called carbon insetting. Another pillar of Cotierra’s business is carbon offsetting, which involves selling voluntary carbon removal credits to industries that want to compensate for emissions already created. This is a huge and growing market, Thomas remarks.

Cotierra completed an oversubscribed USD 1M financial round in early 2024. The startup has already implemented two projects on the ground in Colombia, and Thomas reveals that his team is working on a third one. Collaborating with multinational coffee traders has brought Cotierra some valuable local networks and opportunities to train farmers on using biochar, he notes.

Cotierra’s approach is decentralized. Instead of transporting biomass across long distances to a processing plant, the company brings its reactors to the farmers; one Cotierra reactor can cover approximately 100 farms. This is the best way to reach the right users, Thomas explains, as coffee farms are typically small and far apart. The company’s goal is to reach one million tons of carbon removal capacity by 2028, which corresponds to 10,000 reactors in action, Thomas calculates.

“Switzerland is a huge player in the global coffee value chain”

Four people in a sloping coffee field
Visiting a coffee farm

Cotierra has been international from the start. Switzerland is a huge player in the global coffee value chain while Colombia is a massive coffee producer. Part of Cotierra’s team is based in Colombia, and the company wants to expand to the other major coffee-producing countries: Brazil, Vietnam, Indonesia, and Honduras. Picking Colombia as the starting point was an easy decision: Thomas spent some time in Colombia during his studies, and his wife is from there. These connections have helped Cotierra build and access networks across the two countries.

A Swiss company offering solutions in the Global South could be perceived as patronizing. Thomas assures that Cotierra works hard to be a learning, collaborative partner instead of pretending to know all the answers. Cotierra brings biochar expertise to the table, while farmers have the knowhow on their local environment. “They know much more about their soils and climate; they know much more about their work processes and how our solution can be integrated”, Thomas lists.

Furthermore, it makes sense to focus climate efforts where they have the largest impact, Thomas continues. For biochar, that means operating in the tropics, considering the poor soil, challenging weather, and abundance of biomass. In terms of climate justice, Global South is also the place to be: small farmers in these regions suffer greatly from climate change despite contributing very little to it. Offering smallholder farmers in the Global South ways to improve their livelihoods and combat climate change is the right thing to do, Thomas concludes.

Thomas believes that in ten years we will be able to enjoy our caffeine with a much better conscience. Every cup of coffee will be environmentally positive, he envisions.

This article is partially based on this podcast episode.



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