In Dinant, the kiln will never see a flame: kilning heat comes from a biomass boiler and the electricity is renewable. What that changes for brewers — and what it doesn't.
In a few days, the first tonnes of organic Belgian barley go into the drum at the maltings in Dinant. Five tonnes per batch, roughly one batch a week — we've told that story before. But the question visitors ask most often isn't about steeping or germination. It almost always comes up in front of the kiln: what do you heat with?
Kilning is where the energy goes
Malting is a game of water. Steeping adds it to wake the grain; germination lets it work; kilning takes it out again to put the malt to sleep. Fresh out of germination, green malt holds over 40% moisture. To keep well, mill well and brew well, it has to come down below 5%. On a five-tonne batch, that means several tonnes of water to evaporate, kilo after kilo, in a stream of warm air pushed through the grain bed for more than a day.
Evaporating water is the most stubborn bill in the building. It takes roughly six times more energy to vaporise a litre of water than to heat it from 20 to 100°C. No trick makes that bill disappear; you only choose how to pay it. In any maltings, most of the energy goes right there, into the kiln — far ahead of the lighting, the pumps or the drum itself.
Two centuries of fire under the grain
Old kilns remember the fire. For a long time, a kiln was a perforated floor above a hearth: wood, peat, coal, coke. When the smoke passed through the grain, you tasted it in the glass — peated whiskies still live off that. Modern maltings replaced the hearth with natural-gas burners, usually indirect-fired, with heat recovery on the moist air leaving the grain. Real progress — but the source is still fossil: most of the malt brewed in Europe today is dried with gas.
At five tonnes a batch, the question can be asked differently. At a small scale, you can pick another heat source without redesigning an entire plant. That is the bet made in Dinant, from the first drawings of the building.
Hot water instead of a flame
At MAD, the kiln will never see a flame. The heat comes from a biomass boiler that produces hot water. The water runs through an exchanger, the exchanger warms the air, and the air travels through the bed of malt in the drum — the same drum used for germination, so the grain never has to move. The electricity that turns the drum and drives the fans is renewable. From the start of steeping to the last hour of kilning, no fossil fuel.
Hot water sets its own temperature range. A gas burner climbs fast and high; a hot-water loop works lower and steadier. For the malts we make — pils, pale ale, and darker base malts like munich and vienna — that is exactly the register needed: gentle drying, then a controlled final cure. Caramel and roasted malts need a roasting drum and far higher temperatures: we don't make them, and we say so plainly. A brewer hunting chocolate malt for a stout will keep sourcing it elsewhere.
What changes in the glass — and what doesn't
Let's be honest: you cannot taste the boiler. A pils malt dried with biomass gives the same enzymes, the same colour and the same extract as one dried with gas, kilning schedule for kilning schedule. You will choose a malt on its analysis, its consistency and what it does to your beer — not on its energy label. And when local malt isn't the right choice for a recipe, better to know it than to dress it up.
What changes is the footprint of the sack. Malt weighs heavily in a beer's footprint before the brewhouse even fires up: growing the malting barley, drying it, moving it. A brewery in Namur or Maastricht brewing with Belgian malt dried without fossil fuels shortens two lines at once: the kilometres and the combustion. For an organic spec, a public tender or customers who ask for numbers, that becomes as concrete an argument as a protein figure.
The same logic, applied to water
A sober kiln doesn't make a sober maltings on its own. Steeping takes a lot of water, and that water has its own loop too: part of it is reused, the rest passes through a lagoon basin before returning to nature. Biomass heat, renewable electricity, water that cycles back, organic Belgian barley arriving from the field: each piece counts for little on its own; together they describe a way of making malt that holds up over time — including the day gas prices go wild again.
The boiler is ready, and so is the drum. The first malting campaign starts in November, and with it the first concrete answers to that visitors' question. If you find yourself near Dinant, come and see the kiln up close: the malthouse team is always glad to talk heat, malting barley and kilning schedules, during a visit or through mad.be.