What, Exactly Is Peat and How Did it Get in My Whisky?

Peaty scotch can be a polarizing topic among whisky drinkers — some love it, some hate it, very few are impartial to it. For those who seek out the peat, there’s nothing better than an intensely smoky dram, one that makes your toes curl as the pungent odor hits your nose. But there’s no question that it’s a strange component. So what, exactly, is peat, and how did it get in your glass?

Peat is basically decomposed organic plant matter that has been compressed in the ground for thousands of years, essentially young coal. There is no shortage of peat in Scotland — according to Scottish National Heritage, peat covers approximately 23 percent of the country, mostly in the Highlands and Islands. But it is also found throughout Ireland, northern England, Scandinavia, and parts of Russia and the U.S. According to the International Peatland Society, the largest supply of peat can be found in Canada — this is mostly used for horticultural purposes. But if you're drinking peaty scotch, that source of smoky goodness comes from Scotland's ample native supply.

People originally used peat as an energy source; it burns similarly to coal, smoky and odorous but consistently. According to Simon Brooking, master ambassador of Laphroaig Scotch Whisky, it's difficult to pinpoint when peat was first used to make whisky. "While there is no exact known date," he says, "commercial distilling began in Scotland in the 18th century. Originally, peat was introduced to whisky by Scots who used it to heat the pot stills. However, the "peaty" flavor in Scotch actually comes from the malting process, where the dried barley absorbs the smoke odor from the burning peat used in the drying." Peat may have been used due to the whisky being produced in areas of Scotland like Islay with few alternate sources of fuel, like trees. Since the 1950s, the use of peat as a home fuel has dropped off, but it’s now a commodity prized by certain scotch makers looking for a particular, powerful flavor profile.

Peat used to be cut from the ground by hand. Using a shovel, it's exposed into shelf-like formations. Then a long-handled slicer is used to cut through it to form rectangles that kind of look like slices of fudge cake. Finally, the peat is dried out in stacks for several weeks. At least that’s how it used to happen. Now it’s mostly done with machines. “For a lot of the distilleries on the island, it’s sourced from one massive peat bank that’s then transported to the malting center,” says Douglas “Dugga” Bowman, Ardbeg head warehouseman.

There, the peat is put into a massive kiln and burned underneath the malted barley, stopping the germination process and sending wafts of smoke into the grain. This is the key step in the process that defines the typically smoky character of peated Islay single malts like Ardbeg, Laphroaig, Lagavulin, and Bruichladdich’s Octomore expression. Ardbeg’s various whiskies usually hover in the 50-55 ppm (phenol parts per million) range, making them decidedly peaty but not overbearingly so – the flavors of the base spirit and casks in which the whisky is aged still comes through. “There are lots of different types of smokiness,” says Ardbeg distillery manager Mickey Heads. "You’ve got peaty smoke, earthy smoke, bonfire smoke. Different types of smoke come through depending on your process, your shape of still, and the level of peat.”

In early September, I participated in Ardbeg’s ARDventurer challenge, which brought competitors from all over the world together for three days and two nights of camping, hiking, and undertaking whisky-related challenges. The hills above the distillery are the source of Islay’s peat, where you can find the natural element that defines Islay whisky in its rawest form. Every step threatens to break an ankle as mounds of dirt called “baby heads” obscure deep sinkholes in the sopping, boggy landscape. Hordes of midges (dubbed “the Scottish Air Force” by the locals) swarm any exposed skin as soon as the wind dies down. And dozens of tiny ticks, living in the tall grass above the peat, latch onto the most intimate of areas. Still, getting out into the rough is a great way to understand how and why peat is used in Islay whisky, for which it is an essential and defining ingredient.

Heads makes the importance of peat very clear. “That’s what defines our style, that’s what defines Islay,” he told me as we huffed and puffed our way up the side of a boggy hilltop. “That’s what we’ve always used … it’s part of the [distillery’s] history, going back 200 years.”