Latest / The Manufacturing Podcast with Fexingo: Factories, Supply Chains, and Industrial Business / How a Swedish Factory Is Making Batteries from Wood
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- Lucas: Luna, I want to start today with a number: every year, the global paper industry produces about 70 million tons of lignin. It's the glue that holds wood fibers together, and paper mills typically burn it for low-grade heat because they don't know what else to do with it. Luna: So it's basically a waste stream that's already sitting there, waiting for someone to find a higher-value use. Lucas: Exactly. And a Swedish startup called Ligna Energy thinks they've found one of the most interesting uses yet. They're manufacturing supercapacitors — think of them as fast-charging, long-lasting energy storage devices — using carbon derived from lignin. Their factory in Örnsköldsvik, about 500 kilometers north of Stockholm, started pilot production late last year. Luna: I've heard about supercapacitors — they charge much faster than lithium-ion batteries and last for hundreds of thousands of cycles. But their energy density is usually lower, right? Lucas: That's the trade-off. A lithium-ion battery packs maybe 250 watt-hours per kilogram. A typical commercial supercapacitor is around 5 to 10 watt-hours per kilogram. But Ligna Energy claims their lignin-based carbon can reach 30 watt-hours per kilogram, which is three to six times higher than standard supercaps. And because lignin is abundant and cheap — it costs roughly one-tenth the price of the activated carbon used in conventional supercapacitors — they think they can undercut existing products on cost. Luna: Thirty watt-hours per kilogram still isn't enough to power an electric car for 300 miles. So what's the use case? Lucas: Several very practical ones. First, grid-scale energy storage — think balancing intermittent solar and wind power. Supercapacitors can absorb and release energy in seconds, which is exactly what you need when a cloud passes over a solar farm and output drops suddenly. Lithium-ion batteries are better for storing hours of energy, but supercaps can handle short bursts millions of times without degrading. Luna: So they complement each other. Put a supercapacitor bank next to a lithium battery, and you get both fast response and long duration. Lucas: Exactly. Second use case — electric buses, trams, and trains. These vehicles stop and start frequently, and regenerative braking generates high power for a few seconds. A supercapacitor can capture that energy efficiently and release it when the vehicle accelerates. China already has thousands of supercapacitor buses on the road. Ligna Energy thinks their lignin version could be cheaper and more sustainable than the current carbon source, which is often made from petroleum coke or coconut shells. Luna: Coconut shells? That's the raw material for activated carbon in many supercaps? Lucas: Yes — coconut shells are actually a common source. They're renewable, but they require agriculture, shipping, and processing. Lignin is a byproduct that's already concentrated at paper mills. So you're taking a waste stream and turning it into a high-tech material without additional land use. Luna: And they're doing this at an actual factory. Walk me through the process. Lucas: The factory in Örnsköldsvik is about 2,000 square meters and currently produces around 10 tons of lignin-based carbon per year. The process starts with lignin powder from a nearby pulp mill. They mix it with a chemical activator, then heat it in a furnace to about 800 degrees Celsius in an oxygen-free environment — that's called pyrolysis. The lignin carbonizes and develops a highly porous structure, which gives it a huge surface area — around 2,000 square meters per gram, comparable to the best activated carbons. Luna: Two thousand square meters per gram — that's like a football field's worth of surface area in a tiny amount of material. Lucas: Exactly. That porosity is what stores the electric charge. After pyrolysis, they wash out the chemical activator, dry the carbon, and then coat it onto aluminum foil to make electrodes. Those electrodes are assembled into supercapacitor cells — think of a small coin cell or a cylindrical package similar to an AA battery. The cells are then connected into modules, which can be stacked into larger systems. Luna: So the factory makes the carbon, the electrodes, the cells, and the modules — that's a vertically integrated approach. Lucas: They do the carbonization and electrode coating in-house, but they source the aluminum foil and the separator material from suppliers. The electrolyte — the liquid that carries ions between electrodes — is a standard organic solvent, not proprietary. So their core innovation is the carbon itself: how to process lignin to get consistent porosity and high conductivity. Luna: And they had to solve some challenges to make that work, I imagine. Lignin from different trees or different pulping processes has varying chemical structures. Lucas: That's exactly the hard part. Lignin is not a single molecule; it's a class of complex polymers that vary with tree species, growing conditions, and the pulping method — kraft, sulfite, soda, and so on. Ligna Energy spent years developing a pretreatment process that standardizes the lignin feedstock. They work with a specific type called kraft lignin from Scandinavian spruce, which they get from the nearby paper mill in Örnsköldsvik. That consistency is key for manufacturing reliable supercapacitors. Luna: So they're tied to that particular mill. If they scale up, they'll need to secure consistent lignin supply from multiple sources. Lucas: Right. Their pilot line is proof of concept. They've raised about 15 million euros so far from Swedish and EU clean-tech funds. Their goal is to build a full-scale factory by 2028 that can produce 500 tons of carbon per year — enough for supercapacitors totaling maybe 200 megawatt-hours of storage capacity, roughly equivalent to a small grid battery farm. They're also exploring other products: you can use the same carbon in battery electrodes, fuel cells, and even water filtration. Luna: Let's talk about the economics. Lignin costs maybe $0.50 per kilogram as a waste product. Conventional supercapacitor carbon — activated carbon from coconut shells — costs around $5 to $10 per kilogram. So the raw material cost advantage is clear. But processing adds cost: pyrolysis, activation, washing, drying, coating. What's their target price? Lucas: Ligna Energy says they can produce their carbon for under $2 per kilogram at scale, including processing. That would be a 60 to 80 percent cost reduction versus conventional activated carbon. For a supercapacitor module, carbon accounts for maybe 20 to 30 percent of the total cost. So the overall module cost could drop by 10 to 15 percent, which is significant in a commodity market where every penny matters. Luna: That's compelling. But they're not the only ones trying to turn lignin into carbon. There's a Finnish company called Stora Enso that produces lignin-based carbon for batteries, and a Canadian startup called Lignin Industries. What makes Ligna Energy different? Lucas: Good question. Stora Enso is a giant paper and packaging company — they have their own lignin supply and they're focusing on lithium-ion battery anodes, not supercapacitors. Lignin Industries is more about carbon fiber precursors. Ligna Energy is specifically targeting supercapacitors, which is a smaller but faster-growing market — the global supercapacitor market is expected to grow from about $5 billion today to maybe $12 billion by 2030, driven by grid storage, transportation, and electronics. And their process yields a carbon with very high purity and surface area, which they claim outperforms commercial coconut-shell carbon in cycle life — they've tested 500,000 cycles with less than 10 percent capacity loss. Luna: Half a million cycles is impressive. A typical lithium-ion battery lasts maybe 1,000 to 3,000 cycles. So for applications that need long life, supercapacitors are already superior. If Ligna can make them cheaper and greener, that's a real win. Lucas: One more use case I want to mention: industrial sensors. Factories are deploying more and more wireless sensors for predictive maintenance, vibration monitoring, temperature tracking. These sensors often need to operate for years on a tiny battery, or they harvest energy from vibrations or ambient light. A supercapacitor can store that harvested energy and deliver bursts of power for data transmission. Ligna Energy's carbon could make those energy storage components biodegradable, or at least much easier to recycle than lithium coin cells. Luna: Speaking of making things easier for people, this seems like a good moment to mention something that keeps these conversations going. Lucas, these episodes take a fair amount of research and production to put together — Lucas: They do, and we're grateful that listeners find them useful. If these episodes have moved your work forward in some small way, a couple of dollars a month is genuinely what keeps these going — buy me a coffee dot com slash fexingo. It's a simple way to support ad-free, independent content like this. Luna: Yeah, it really does make a difference. We've heard from listeners who've used examples from this show in their own pitches or projects, and that feedback is what keeps us curious. Lucas: Alright, back to lignin. So we've talked about grid storage, transportation, and sensors. But there's another angle I find fascinating: the geopolitical implications. Europe imports most of its lithium, cobalt, and graphite for batteries from China, the Democratic Republic of Congo, and Chile. Lignin is a domestic resource — Sweden alone has vast forests, and the pulp and paper industry is well established. If lignin-based supercapacitors can replace some lithium-ion applications, it reduces Europe's dependence on critical mineral supply chains. Luna: So it's not just green; it's strategic. Energy storage made from trees, in a region that has a lot of trees. Lucas: Exactly. And the technology is not limited to Sweden. The US has significant lignin waste from its paper industry — about 10 million tons per year. So there's potential for similar factories in the Pacific Northwest, the Southeast, or Canada. Ligna Energy has said they're open to licensing their process to pulp mills globally. Luna: Let's talk about the environmental impact. Are there any downsides to scaling lignin carbon production? Lucas: The main concern is energy use. Pyrolysis at 800 degrees Celsius requires heat, and if that heat comes from fossil fuels, the carbon footprint increases. Ligna Energy's factory in Örnsköldsvik uses electricity from Sweden's largely hydro and nuclear grid, so their process is very low carbon. But if a similar factory were built in a coal-heavy grid, the environmental benefit would be smaller. Also, the chemical activator — they use potassium hydroxide — has its own production footprint and needs to be recovered or disposed of responsibly. Luna: So the local energy mix matters a lot. That's a reminder that 'green' manufacturing is not just about the material, but the whole system. Lucas: Right. And on the positive side, Ligna Energy is doing a life-cycle assessment to compare their product to conventional supercapacitor carbon. Early results suggest about a 70 percent reduction in global warming potential, mainly because they're avoiding the agricultural land use and shipping associated with coconut shells, and because the carbon is fixed in the product rather than burned as low-grade fuel. Luna: Seventy percent is significant. One last thing — what would it take for this to become mainstream? Is the bottleneck technical or commercial? Lucas: I'd say commercial. The technology works at pilot scale. Now they need to prove they can produce consistent quality at 500 tons per year, and then convince large supercapacitor manufacturers like Maxwell Technologies, Skeleton Technologies, and Panasonic to qualify their carbon. Qualification can take two to three years. They also need to compete on price with established Chinese suppliers who produce activated carbon from coal at very low cost. So the next few years will be critical. Luna: It's a classic scale-up story: can you go from a promising pilot to a reliable, cost-competitive product. But the raw material advantage is real. Lucas: It is. And I think we'll see more of these bioeconomy factories in the coming decade — turning what was once waste into high-value energy materials. Ligna Energy is just one example, but it points to a broader shift: the factory of the future might not just make things; it might also clean up the waste of other industries.