Distilling with altitude: Understanding the impact of elevation on whisky making

As elevation changes, so does whisky making
By Matt Strickland
The still house at Orma Distillery.
The still house at Orma Distillery.
The modern whisky landscape is inhabited by a panoply of practitioners and spans six of the seven continents. From the traditionalists forging fantastic whiskies in Scotland, Japan, Canada, the US and beyond to the mercurial craft distillers dotting points all over the globe, great whisky really can be made virtually anywhere. Just a short while ago, no one would have thought that unforgettable drams would be pouring forth from countries and regions that, up until relatively recently, were not known for whisky production.

Single malt made in the polar reaches of the Arctic Circle? Yes, please. How about a dram or two from hot and humid Southeast Asia? Absolutely. Tequila and Mexico are intrinsically linked, but what about Mexican corn whisky matured in arid warehouses? Sounds delicious.

Of course, this is merely speculating about geography from the points of longitude and latitude. There is a rarely discussed third dimension to consider when it comes to whisky real estate: altitude. Some distillers are already operating in the upper reaches of elevation, and there’s a growing body of evidence that this variable is influencing the way they make their whiskies and how those spirits taste.

Distillation is simply the process of physically separating compounds by exploiting differences in their boiling points and volatilities. If a distiller heats and boils a one-to-one mixture of water and ethanol, there will be a higher percentage of ethanol in the resulting vapour (approximately 80–85 per cent) and a smaller percentage of water. And that is really all whisky is – a mixture of water and ethanol with incredibly small amounts of flavour and aroma compounds exerting their influence.

This concentration of alcohol occurs partly because ethanol boils at 78.4°C (173.12°F) and water at 100°C (212°F) with various mixtures of the two boiling at temperatures in between. The more ethanol contained in the solution, the closer the mixture’s boiling point will be to 78.4°C. Likewise, the more water there is, the closer the boiling point gets to 100°C.

The breathtaking location of Hakushu Distillery

f cooking, that water boils at different temperatures depending on the altitude. This is because atmospheric pressure (which is literally the pressure the surrounding atmosphere exerts on people and their surroundings) changes with elevation. The higher the elevation above sea level, the lower the atmospheric pressure experienced. For every 300-metre increase in elevation, the boiling point of water decreases by about 1°C (1.8°F). In fact, if someone were to try and boil water on the peak of Mount Everest, the thermometer would top out at around 70°C (158°F). This phenomenon potentially leads to some intriguing effects on the distillation of whisky.

To find out how, it might be helpful to look outside the world of whisky to that of Japanese shōchū. Some shōchū is distilled on specially designed stills that create an internal vacuum. This vacuum distillation lowers the pressure inside the still and, thus, the boiling points of its contents. These distillers are effectively creating high-altitude conditions in their stills, sometimes to extreme degrees. The distiller’s wash in these stills can start evolving spirit vapours as low as 50°C. (This is to say nothing of a few notable gin distillers who are using similar stills to reduce pressures and boiling points down to as low as -5°C.) The end result of these distillations is often a new-make spirit characterised as clean, fruity, and one that carries many of the aromas of the original fermentables.

Low-pressure distillation also makes the simple separation of flavour congeners much easier to control. If the distiller is paying close attention and running the spirit still at a careful clip, they can theoretically separate high-volatility congeners such as methanol more easily. And while methanol in high concentrations is certainly toxic to humans, small amounts of it also serve as precursors to the formation of various esters. Ethyl acetate is the most important of these esters and contributes a solvent note to the whisky that in certain amounts can come across as ethereal and fruity. In some styles of whisky such as bourbon, ethyl acetate may be desirable, but, in others, it may throw the balance of the final dram completely out of whack.

It isn’t just the low pressure that changes things. The general reduction in heat can also have an impact by reducing the formation and carryover of some heavier flavours such as furfural. Furfural is an aromatic aldehyde common in many spirits including whisky, and it is often described as having bready or caramel-like aromas.

While there aren’t many whisky distillers practising their alchemical arts at high altitude, there are a few notable examples. In Scotland, Dalwhinnie is working at 350 metres (1,148 feet) above sea level. And while they produce a lovely, honeyed style of whisky, this altitude is perhaps not quite a truly high elevation. However, traverse Eurasia and hop over to Japan, and there are a few distilleries located closer to the clouds.

Prior to its permanent closure in 2011, Karuizawa had been making whisky at 850 metres (2,788 feet) above sea level. The auction record–setting whiskies from this distillery express elegance and an abundance of fruit. Currently operating at around 800 metres (2,624 feet) in Japan’s Nagano Alps is the Mars Shinshu Distillery, whose whiskies are nuanced, floral, and delicately fruity. Not to be outdone, Suntory’s Hakushu Distillery was built at 700 metres (2,296 feet) above sea level on the slopes of Mount Kaikoma. The altitude, coupled with its distillers' precise and exacting techniques, produces phenomenal whiskies with flavours masterfully balanced on a razor’s edge.

Breckenridge Bourbon Whiskey

When asked about the effects of altitude on their whiskies, the distillers from Hakushu share their thoughts: “The company was not intentionally looking for a place with a high elevation, but [it] was a result of our search of [sic] a different type of whisky from Yamazaki [one of the company’s other malt distilleries]; a place with a different environment, with high-quality water and rich nature. In general, higher elevations are associated with cooler year-round temperatures and cooler climates, which are thought to result in less extraction of components from the barrel wood and slower maturation.”

Notably, Suntory has even sent whisky into space to understand how zero gravity affects maturation. Based strictly on numbers, outer space would certainly take the cake for high elevation. Fortunately, there’s more high-altitude whisky goodness to be had down here on terra firma.

Next, take a jet lag–inducing flight across the Pacific to the United States, the land of bourbon and rye. Drive up into the Rockies for beautiful vistas, skiing and some fantastic whiskey distilleries. One of the most important of these distillers, especially in the context of high-altitude distilling, is Breckenridge Distillery located in Breckenridge, Colorado. Started back in 2008 and situated at the comparatively anoxic elevation of 2,920 metres (9,580 feet), Breckenridge claims to be the highest operating whiskey distillery in the world. The team focuses its efforts on a singular product line of blended bourbons. Breckenridge distils its high-rye mash bill of 56 per cent corn, 38 per cent rye, and six per cent malted barley and then matures it for two to three years in new charred oak.

The resulting liquid is then blended with other high-quality bourbons from Tennessee, Kentucky, and Indiana, making for a more rounded and complex product. Bryan Nolt, founder of Breckenridge, says, “From a physics perspective, distillation at this altitude is much more efficient due to lower atmospheric pressure, so evaporation occurs at lower energy input. In our case, we use less steam to distil which saves energy and uses less natural gas. Given the differences in cut timing and energy inputs, our high wines have a unique nose and flavour profile that pleasantly surprises everyone who tries them from the spirit safe during distillation. Best we can tell, the difference is syrupy sweetness with a little graham cracker that you actually want to drink even at 138 proof.”

Breckenridge Distillery

Next, jump on a flight to Switzerland and, in addition to opening a bank account, checking the time on a new watch and breaking off a piece of delicious chocolate, make sure to visit Orma Whisky Distillery. Located at 3,300 metres (10,826 feet) above sea level, this small whisky maker may have Breckenridge slightly beat on the elevation front. Its focus is on single malt whisky with a small amount of gin production as well. Distilling whisky at such a high altitude is an interesting endeavour. The company says that the resulting distillate is more aromatic than similarly distilled spirits at sea level, with much of the initial grain character preserved.

“We have a boiling point over 10°C (18°F) lower than sea level. For ethanol it’s around 8°C (14.4°F) lower,” says Pascal Mittner, co-founder of Orma. “This has a big impact to [sic] the taste, as more flavours will survive because of lower temperatures, and this makes the new spirit more complex. What impact it will have for the whisky we can’t tell you now, as we started distilling at this altitude less than two years ago. We believe it will have a big one as you have already more flavour in the new spirit.”

Like so many things surrounding the production of fine whisky (and other spirits), the total effect of elevation on whisky aroma and flavour is little understood. But the mystery is also partly what makes whisky so charming. The unknown factors and variables remain mystical and magical. And even as we continue to root out the various chemical, physical, and biological mechanisms behind drams divine, the majesty and allure of fine whisky will always remain.