BlogThe farm that accidentally built a pyrolysis boiler companyDate29 April 2026AuthorRoss Kenyon

On this pageIf no one’s making it, make it yourselfHeat, biochar, and the economics of bothFrom farmer to manufacturerThe certification challengeWhy they chose RainbowGrowth at their own pace

If no one’s making it, make it yourselfEdvard Hamilton didn't set out to become a biochar equipment manufacturer. He just wanted better soil.His family farm in southwestern Sweden—two hours north of Gothenburg, tucked into the mountains—has been in Hamilton hands since 1763. The soil is thin, rocky, and unforgiving. Standard fertilizer works for a season and then disappears. You buy it, it's gone, you buy it again. In 2015, Edvard came across biochar and saw something different: a soil amendment you invest in once, and that keeps working for generations. He tried to buy some. Nobody was actually making it."They all had nice websites," he says, "but no one is making this. They just have an idea." When he said as much out loud, the response was blunt: Do it yourself, then.So he did. In February 2018, smoke rose from the chimney at the Hamilton farm for the first time. That became the biochar project developer, Biokol. It hasn't stopped since.Edvard Hamilton next to an enormous bag of his biochar.

Heat, biochar, and the economics of bothFrom those humble beginnings, Edvard launched his biochar project development company, Biokol.To understand why Biokol works as a business, you need to understand that the pyrolysis boiler solves two problems at once, and that both matter to making the numbers work.Sweden is cold. Old stone farmhouses with meter-thick walls need a lot of heat. Grain coming in from the fields has to be dried to precise moisture levels before storage. Chicken barns need floor heat year-round. Every farm that buys a boiler from Biokol’s manufacturing arm has a pre-existing, urgent heating problem to solve. The boiler, available in 160-kilowatt and 400-kilowatt models, addresses it by running wood residues and FSC-certified forestry waste through a pyrolysis process at 750°C, generating both hot water and biochar simultaneously. Some customers supply heat to entire district heating networks, warming the outskirts of small municipalities.But heat alone doesn't justify the capital cost. A boiler runs 7–12 million SEK ($0.75-1.3M USD)—several times the price of a conventional wood-burning unit. That gap is where carbon credits become essential. Biokol's project documentation shows that revenue from carbon removal credits represents roughly 40–45% of total project revenues. Without it, the economics don't work. With it, the boiler pays for itself while also solving a real heating need, creating an impactful soil amendment, and locking carbon into the soil for up to 1,000 years."All of them have a heat demand," Edvard says. "That's why we help them find the right machine."The feedstock story adds another layer. Biokol's primary input is trees damaged by the spruce bark beetle—wood that would otherwise be burned or left to decompose. Rather than release that stored carbon back into the atmosphere, the pyrolysis process locks about 90% of it into stable biochar with a verified carbon content around 90% by weight. Each tonne of biochar sequesters approximately 2–3 tonnes of CO₂ equivalent. The forestry residues are FSC- and PEFC-certified, meaning the entire supply chain is documented and auditable.Get yourself a boiler that also makes biochar.

From farmer to manufacturerThe first pyrolysis machine Edvard bought came from Germany. It arrived unfinished, untested, and riddled with what he politely calls "childhood diseases." He leaned on friends with welding companies, got it working, and started making biochar. Word spread, before and around COVID, the farm was hosting an average of three visitor groups every week. Everyone who came wanted to do the same thing: make biochar and heat simultaneously.That's how Biokol’s manufacturing division was born. What started as a farm soil project became a machine manufacturing company, and then a network: 26 pyrolysis boilers now operating across Sweden, across two owned project sites—Hjelmsäter in Hällekis and Kisebo in Hjo—plus machines sold to independent operators throughout the country.Each boiler links to a touchscreen controller accessible from anywhere via phone. Edvard can log in remotely, adjust parameters, and troubleshoot problems in real time. More critically for carbon markets, the system continuously logs that biomass stays inside the pyrolysis chamber for at least 90 minutes at temperatures above 750°C—the conditions verified to produce high-quality, high-permanence biochar. That data trail is not incidental; it is the foundation of every credit issued.When customers call on a Friday night with a machine problem, Edvard can log in remotely, diagnose the issue, and help them fix it. He describes it simply as a win-win.Edvard showing off his machine’s ability to communicate back to him.

The certification challengeHere is where the story becomes relevant to any biochar producer thinking about carbon markets.Getting a carbon credit isn't just about making good biochar. It's about documentation: chain of custody, lab results, transport records, temperature logs, random reflectance tests per batch, third-party audits. For a farm operator whose primary job is heating buildings and growing grain, this is a real burden. Some registries impose minimum production requirements for tonnes per year that effectively exclude smaller producers before they even begin.Sofia Hamilton, Edvard's wife and partner, came to this problem with a useful background: a Certified Internal Auditor with years in internal audit and compliance at a major financial institution in the U.S., where she learned that undocumented work simply doesn't exist. Rather than leave each boiler operator to navigate certification alone, she built a network model. Biokol connects boiler customers into a shared certification program—handling the documentation, audit preparation, and lab coordination centrally, then profit-sharing on credit sales. The farm operator focuses on running their operation. Biokol handles the paperwork. Credits are certified and issued through Rainbow."We can take that on," Sofia explains. "We collect the information from them, and then sell the credits."The results of that approach are visible in the credit numbers. Biokol issued just 46 credits in 2023, its first verified year. By 2024 that grew to 564. In 2025 it reached 1,548. The project is on track to issue more than 20,000 credits across its five-year crediting period. Their trajectory started small, and has since scaled significantly. This trajectory represents the exact kind of project Rainbow is engineered to support.

Why they chose RainbowBiokol started certifying its credits through Rainbow after about a year of discussions. (They left their previous registry because its scale requirements excluded the kind of small producers Biokol’s boiler serves.) The relationship has become something more than a registry arrangement."We never felt like we're alone, like we can't reach them," Sofia says. "Even if it's a question I consider dumb, I feel like they're available." The contrast with other experiences is stark. She recalls registries where emails went unanswered for a quarter.Rainbow's Arc platform drew specific praise. Earlier in the relationship, documentation lived in Google Drive folders, what Sofia diplomatically describes as "one hodgepodge mess." Arc gave her a structured place to attach supporting evidence exactly where auditors needed it. "I knew they had what they needed," she says.Edvard is more direct about what a responsive registry is worth: "Sending an email, asking a question, you get an answer in hours."

Growth at their own paceBiokol has taken no outside investment. In a sector where several well-funded carbon removal companies made loud promises around 2022 and 2023 and subsequently went quiet, that independence looks like a strategic asset."We were very happy we didn't jump on that train," Edvard says.Current plans call for three new sites in the next audit cycle, potentially six in the one after that. With roughly 17 new boiler orders potentially moving through Swedish government subsidy programs, faster growth is possible, but the intention is to add sites at a pace that keeps documentation quality and compliance intact."Going slow and steady is good," Sofia says. "We don't want to bite off more than we can chew."For other biochar producers weighing their registry options, what Biokol has built is worth examining: a model where a heat-first business generates verified carbon removal as a second revenue stream, where the boiler manufacturer supports one throughout the operational lifespan of the boiler, and where a registry relationship is built on responsiveness and shared interest in getting it right.The farm is still there. The stone walls still need heat. The spruce bark beetles are still damaging forests nearby. And across Sweden, 26 chimneys are still turning waste wood into something that will stay in the ground for a thousand years.Sunset over Hjelmsater's Biochar Big Bags.