Latest / The Manufacturing Podcast with Fexingo: Factories, Supply Chains, and Industrial Business / How a British Factory Makes Hydrogen from Whisky Waste
Transcript
- Lucas: Luna, I want to talk about something that sounds almost too neat to be true — making hydrogen fuel from the leftover goop of Scotch whisky distillation. Luna: You mean the stuff that comes out of the still after the alcohol is taken off? That dark, grainy liquid? Lucas: Exactly. It's called pot ale, and there's a lot of it. Every litre of Scotch whisky produces about eight litres of pot ale and two kilograms of spent grain. Traditionally, distilleries either spread it on farmland as fertiliser or send it to anaerobic digesters for biogas. But a company called Celtic Renewables has been working on a different path — turning that waste into hydrogen. Luna: Hydrogen is tricky to transport and store, though. Are they making it right at the distillery? Lucas: That's exactly the idea. They set up a pilot plant at the Rothes Distillery in Speyside, Scotland, which is right in the heart of whisky country. The process starts with a bacterial fermentation step — similar to how you'd make ethanol — but instead of purifying the alcohol, they use the organic acids produced to feed a microbial electrolysis cell. That cell uses a small electrical current to split the acids into hydrogen and carbon dioxide. Luna: So it's not traditional water electrolysis. It's biological, with a little electricity boost. Lucas: Right. And the electricity can come from renewables — the distillery already has solar panels on its roof. The hydrogen they produce is clean enough to feed into a fuel cell or burn in a modified boiler. In the pilot, they're generating about 20 kilograms of hydrogen per day. That might sound small, but it offsets roughly 50 percent of the distillery's natural gas consumption for heating. Luna: Fifty percent from waste that was previously just a disposal cost. That's a real number. Lucas: And it cuts CO2 emissions by about 140 tonnes per year for that one site. Scale that across Scotland's 130-plus malt whisky distilleries, and you're looking at a potential reduction of over 18,000 tonnes annually. Luna: What about the economics? Hydrogen production is usually expensive compared to natural gas. Lucas: The key is that the feedstock — the pot ale and spent grain — is essentially free or even negative cost, because distilleries currently pay to have it removed. Celtic Renewables says their levelised cost of hydrogen is around four to five dollars per kilogram, which is competitive with green hydrogen from grid electrolysis, and it avoids the transport cost because it's produced on-site. Luna: So the distillery saves on waste disposal AND on natural gas. That's a double win. Lucas: Exactly. And the hydrogen can also be used to power forklifts or delivery trucks within the distillery campus. The whole system is designed to be modular — a shipping container sized unit that can be dropped into any distillery, brewery, or even a paper mill, because those industries produce similar organic waste streams. Luna: Paper mills have that black liquor waste, right? Full of lignin and organics. Lucas: Exactly. The same fermentation-electrolysis process can handle it. So the potential addressable market isn't just whisky — it's any facility that generates high-strength organic wastewater. That's thousands of sites globally. Luna: Are there any challenges that could slow adoption? Aside from the usual regulatory hurdles. Lucas: The biggest one is the hydrogen infrastructure itself. Even if you produce it cheaply on-site, you still need a way to use it — either a fuel cell, a hydrogen boiler, or a blending system for the natural gas grid. Many distilleries don't have those yet. But the Scottish government has been funding hydrogen-ready boiler conversions, and the UK's hydrogen strategy includes blending targets for the gas network. Luna: So it's a chicken and egg problem, but the egg is getting cheaper. Lucas: That's a good way to put it. Celtic Renewables is currently scaling up from the pilot to a commercial demonstration plant that will produce 200 kilograms per day, enough to fully displace natural gas at a medium-sized distillery. They've secured funding from the UK's Net Zero Innovation Portfolio. Luna: I also read that they're partnering with a brewing company to test the same process on beer waste. That could be huge — there are so many breweries everywhere. Lucas: Yeah, brewing waste is very similar chemically. And breweries have the same problem: they pay to get rid of spent grain and wastewater. If this works at scale, you could see hydrogen production become a standard add-on for any fermentation facility. Luna: It also fits neatly into the circular economy narrative — waste from one process becomes fuel for the same process. Lucas: Exactly. And it's not just about carbon. It also reduces the methane emissions that would come from letting the waste decompose in a landfill or open lagoon. So the climate benefit is actually larger than just the fossil fuel displacement. Luna: That's a good point. Methane is much more potent as a greenhouse gas. Lucas: Right. So you're avoiding methane release AND displacing natural gas. That's a double climate win. Luna: What about the water footprint? The hydrogen process itself uses water, but you're also recovering water from the waste stream, right? Lucas: The fermentation step actually cleans the water to some extent. The effluent from the microbial electrolysis cell is much lower in organic content, so it can be discharged more safely or even reused in the distillery's cooling systems. Celtic Renewables claims the overall water balance is neutral to positive. Luna: So you're not trading one environmental problem for another. Lucas: That seems to be the case. And the technology is not that exotic — it's a hybrid of well-understood anaerobic digestion and low-voltage electrolysis. The real innovation is in the microbial community that efficiently converts the organic acids. Luna: I can see this being a great case study for students in industrial ecology or chemical engineering. Lucas: Absolutely. And it's exactly the kind of thing we like to cover — specific, scalable, with real numbers attached. Luna: Speaking of which, these deep dives take a fair bit of research to put together. If you've gotten something out of them, a couple of dollars a month is genuinely what keeps these going — buy me a coffee dot com slash fexingo, if you've found it useful. Lucas: Yeah, it's a small thing that makes a big difference for us. And it helps us stay ad-free and focused on the stories that matter. Luna: Alright, back to the hydrogen. One more thing that surprised me: the energy efficiency of the whole process. Lucas: What about it? Luna: I saw a paper that claimed the overall energy efficiency — from waste to hydrogen — can exceed 70 percent, which is higher than conventional water electrolysis at around 60 to 70 percent. Lucas: That's because you're using the chemical energy already stored in the waste. Water electrolysis has to supply all the energy from electricity, whereas here the bacteria provide some of the energy by breaking down the organic molecules. So you get a kind of energy bonus. Luna: Right. So it's not just cheaper feedstock — it's also more efficient conversion. Lucas: Exactly. That combination is what makes the economics work. If the commercial demo succeeds, I think we'll see this spread quickly, especially in regions with strong distilling or brewing industries — Scotland, Ireland, Kentucky, Japan, Canada. Luna: And maybe even wineries? Grape pomace has similar organic content. Lucas: Possibly. Wine waste is more acidic and has more tannins, so the microbial community might need adjustment. But the principle is the same. Luna: So to sum up: whisky waste hydrogen is real, it's cost-competitive, and it solves two problems at once. Lucas: And it's happening right now at a distillery in Scotland. That's the kind of concrete progress that makes me optimistic about industrial decarbonisation. Luna: Cheers to that — maybe literally, with a glass of Scotch made from that very distillery. Lucas: I'll drink to that. For The Manufacturing Podcast, I'm Lucas. Luna: And I'm Luna. See you next time.