Latest / The Manufacturing Podcast with Fexingo: Factories, Supply Chains, and Industrial Business / How a Danish Factory Uses Waste Bread to Make Biofuels
Transcript
- Lucas: Luna, have you ever thought about what happens to all the bread that bakeries don't sell by the end of the day? Luna: Honestly, no. I assume it gets composted or maybe donated. But I'm guessing there's a more industrial answer coming. Lucas: There is. In Denmark, a company called Biogas Energy — actually, they rebranded to a name I can never pronounce — runs a factory just outside Copenhagen that takes about 70,000 tons of bread waste every year and turns it into biofuel. Luna: Seventy thousand tons. That is a lot of unsold rye bread. Lucas: It's mostly from industrial bakeries and supermarket returns. Stale loaves, sandwich bread, pastries that hit their sell-by date. The factory grinds it all up and turns it into cellulosic ethanol — basically, ethanol made from the starch and sugars in the bread. Luna: So it's not just burning bread for heat. They're actually making a liquid fuel. Lucas: Exactly. And they're doing it at scale. The output is about 20 million liters of ethanol per year. That gets blended into gasoline for cars in Denmark and Sweden. Luna: What's the carbon math on that? Does it actually beat gasoline? Lucas: According to the company's lifecycle analysis, the fuel has a carbon footprint about 60 percent lower than regular gasoline. The key is that the bread waste was going to rot in a landfill and emit methane, which is far worse for the climate than CO2. So you get a double benefit: you avoid the methane, and you displace fossil fuel. Luna: So it's almost like a credit on both sides. That's pretty compelling. Lucas: It is. But what I find really interesting is the technology. The factory uses enzymes from Novozymes — that's the Danish biotech giant — to break down the starches into fermentable sugars. Then they use yeast to convert those sugars into ethanol. It's not new in theory, but doing it at this scale with waste bread is surprisingly tricky. Luna: What's the trick? Bread has a lot more than just starch. There's fat, protein, salt. Doesn't that gum up the fermentation? Lucas: Exactly. The fat and protein can inhibit the yeast, and the salt can be toxic at high concentrations. So the factory had to develop a custom pretreatment process. They heat the bread slurry to break down the fats, then centrifuge out the solids, then add the enzymes in a specific sequence. It took them about three years to get it right. Luna: So this isn't a off-the-shelf solution. They had to engineer around the specific chemistry of bread. Lucas: Exactly. And that's why most similar projects in other countries have struggled. In the UK, a company called Bio-fuel Solutions tried a similar approach a few years ago and went bankrupt. The economics are tight because bread waste itself is cheap — sometimes bakeries pay to have it taken away — but the processing cost per liter is high. Luna: How does the Danish plant make the numbers work? Are they getting subsidies? Lucas: They benefit from Denmark's renewable fuel mandate, which requires a certain percentage of biofuel in road fuel. But the company says the plant is profitable on its own, as long as they don't have to pay for the bread waste. And they don't — they charge bakeries a disposal fee that's lower than what a landfill would charge, so both sides win. Luna: It's a classic waste to value model. The feedstock is actually a revenue source, not a cost. Lucas: That's the key. And they've already started expanding. Last year, they announced a second facility in southern Sweden that will handle 50,000 tons of waste from bakeries there. Luna: I want to touch on something broader. Globally, about one-third of all food produced is wasted. If you could replicate this model in every major city, how much fuel could you produce? Lucas: A study from the University of Copenhagen estimated that if you took all the bread waste from the top 50 bakery-producing countries, you could produce about 10 billion liters of ethanol annually. That's about 2 percent of global gasoline consumption. It's not a silver bullet, but it's a meaningful chunk. Luna: And you're not competing with food crops, which is the big criticism of corn-based ethanol. Lucas: Right. No land use change, no fertilizer inputs, no water stress. That's what makes the carbon math so good compared to corn ethanol, which only saves about 20 to 30 percent versus gasoline. Luna: So the Danish plant is a proof point. But what's stopping other countries from building these? Is it the enzyme cost? The pretreatment complexity? Lucas: It's mostly the logistics of collecting bread waste. You need a dense network of bakeries within a short trucking radius, because bread is heavy and bulky relative to its energy content. The Danish plant has about 200 bakeries within 50 kilometers. In a city like New York or London, you'd have the density, but you'd also have much higher real estate costs for the plant itself. Luna: And you'd need the regulatory push. Denmark has a carbon tax and a biofuel mandate. In the US, the Renewable Fuel Standard includes cellulosic ethanol, but the credits for it — the RINs — have been volatile. Lucas: That's exactly the issue. The economics depend a lot on policy certainty. The Danish plant was built with a 10-year fixed price for the ethanol they sell, guaranteed by the government's fuel blending requirement. That kind of stability matters. Luna: It's interesting to see how a small country with high waste disposal costs and high fuel taxes can make this work. It's not a model that copies and pastes easily. Lucas: No, but it shows what's possible. And the company is now licensing its technology to a project in the Netherlands that will use potato waste from the french fry industry. So they're broadening the feedstock. Luna: That makes sense. The enzyme process is probably similar — starch is starch, whether it comes from bread or potatoes. Lucas: Exactly. And that's where I think the real innovation is. It's not the idea of making fuel from waste, it's the engineering to handle the specific impurities in each waste stream. That's the hard part, and that's what the Danish team has figured out. Luna: You know, speaking of figuring out hard problems, I think a lot of people in our audience are listening to these episodes to get ideas for their own work. If you've found this conversation useful in thinking about your own manufacturing or supply chain, it's worth mentioning that listener support is what keeps this podcast going without ads. We're listener-funded, and that means we can dive into niche topics like this without worrying about pleasing sponsors. Lucas: Yeah, that's right. If you've gotten something out of these episodes — maybe a new angle on a problem you're facing — consider supporting us at buy me a coffee dot com slash fexingo. It's a simple way to help us keep doing deep dives into specific factories and technologies. Luna: And it genuinely makes a difference. So, back to the Danish plant — I want to ask about the next step. Once you have the ethanol, what happens to the leftover solids? There must be residue after fermentation. Lucas: There is. It's a wet cake that's high in protein and fiber. The company sells it as animal feed — mainly to pig farms in Jutland. So the bread waste ultimately becomes fuel, feed, and CO2. Almost nothing is wasted. Luna: That's a truly circular process. The only emissions are the CO2 from fermentation, which is biogenic — it was captured from the atmosphere by the wheat plants. So net zero. Lucas: Exactly. And the plant is looking at capturing that fermentation CO2 for use in greenhouses or carbonated beverages. That would add another revenue stream. Luna: So the factory is almost a full biorefinery, not just a fuel plant. They're extracting value from every stream. Lucas: That's the vision. And I think that's the future for this kind of distributed manufacturing. You don't build a giant corn ethanol plant in the Midwest. You build smaller facilities near cities, processing local waste streams into multiple products. The Danish plant is a great example of that model in practice. Luna: Alright, I'm going to start paying attention to what my local bakery does with its day-old bread. Lucas: Maybe it's going into your gas tank. Thanks for listening.