Greener snowmaking is helping ski resorts weather climate change

Trudging across the top of Bromley Mountain Ski Resort on a sunny afternoon in January, Matt Folts checks his smartwatch and smiles: 14 degrees Fahrenheit. That is very nearly his favorite temperature for making snow. It’s cold enough for water to quickly crystallize, but not so cold that his hourslong shifts on the mountain are miserable.

Folts is the head snowmaker at Bromley, a small ski area on the southern end of Vermont’s Green Mountains. The burly 35-year-old sports a handlebar mustache, an orange safety jacket, and thick winter boots that crunch in the snow as he walks. A blue hammer swings from his belt.

It is nearing the end of the day for skiers, but not for Folts. He’ll work well into the evening preparing the mountain for tomorrow’s crowd. Cutting across the entrances to Sunder and Corkscrew, he heads toward a stubby snow gun used to blanket Blue Ribbon, an experts-only trail named in honor of Bromley’s founder, Fred Pabst Jr. The apparatus stands a few feet high, with three legs and a metal head that’s angled toward the sky. Two lines that resemble fire hoses supply the device with water and compressed air, which it uses to hiss precipitation into the air. As the water droplets fall, they coalesce into snowflakes. 

“If it was warmer I’d be a yeti,” says Folts, referring to wetter snow that, if conditions were just a bit balmier, would leave him abominably white. But at these temperatures the powder he’d just made bounced lightly off his sleeve. “That’s perfect.”

Yet perfect fake fluff like Folts’ poses a climate conundrum. On one hand, making snow requires enormous amounts of energy, which creates planet-warming emissions. On the other, a warming planet means that artificial snow is increasingly essential to an industry that, while admittedly a luxury, pumps over $20 billion annually into ski towns nationwide. The good news is that, in the face of these growing threats, resorts have been dramatically improving the efficiency of their snowmaking operations — a move they hope will help them outrun rising temperatures.

American ski areas logged more 65 million visits last season. A sizable chunk of those likely came during Christmas week, when a resort can make — or lose — a third or more of its annual revenue. The Martin Luther King Jr. and Presidents Day weekends are similarly vital. But ensuring that there’s a surface to slide on is an increasingly fickle business. 

Snowpack in the Western U.S. has already declined by 23 percent since 1955, and climbing temperatures have pushed the snowline in Lake Tahoe, California — which is home to more than a dozen resorts — from 1,200 to 1,500 feet. A recent study found that much of the Northern Hemisphere is headed off a “snow-loss cliff” where even marginal increases in temperature could prompt a dramatic loss of snow. 

Matt Folts checks a snowmaking gun that is blowing fresh flake on the Blue Ribbon trail at Bromley Mountain Ski Resort. Tik Root / Grist

By one estimate, only about half of the ski areas in the Northeast will be economically viable by mid-century. Research suggests that Vermont’s ski season could be two to four weeks shorter by 2080, while another study found that Canada’s snowmaking needs will increase 67 to 90 percent by 2050. At Bromley, snow guns have been essential for years; without them, the resort’s mid-January trail count would have likely been in the single digits, rather than 31.  

Opening terrain, however, comes at a cost. It takes a lot of horsepower to move water up the hill under pressure, and compress the air the guns need to function. Bromley’s relatively small operation, which produces enough snow each season to cover about 135 acres in three or more feet of the stuff, chews through enough electricity each year to power about 100 homes. All that juice adds nearly half a million dollars to the resort’s utility bill.

But Bill Cairns, Bromley’s president and general manager, says the system is actually much more efficient than it was just a decade ago. “I used to spend about $800,000,” he says. He’s now able to produce more snow for around half the price. “The reduction in cost with snowmaking has totally been a game changer.” 


Powder days start with specks of dust high in the atmosphere. As they fall, water droplets attach to them, forming snowflakes. Ski areas like Bromley replicate this natural process using miles of pipes that feed water and compressed air to hundreds, sometimes thousands, of snow guns scattered across a mountain. 

Early guns mixed compressed air and water inside a chamber, and then used air pressure to propel water droplets skyward through a large nozzle. This was the type of system Fred Pabst Jr., of beer family fame, spent $1 million installing in 1965, making his resort one of America’s earliest adopters.

“It was a black art. We knew nothing,” says Slavko Stanchak, whose inventions and expertise have made him a legend among snowmakers. It was an era when energy was relatively cheap and resorts would rent rows of diesel-powered compressors that threw whatever snow they could generate on the hill. But as energy costs rose in the 1990s and early 2000s, so did the impetus to innovate.

“We focused on making the process viable from a business standpoint,” Stanchak says.

He eventually launched a consulting company that helped ski areas, including Bromley, design or improve their snowmaking operations. On the water side of the equation, Bromley spent the 1990s improving its piping network and added a mid-mountain pump to help get H2O from its ponds to its trails. (Much of the water eventually returns to the watershed during the spring melt.) But the amount of water needed to carpet a ski hill in snow remains relatively fixed from year to year, so there are only so many efficiency gains to be had. Compressing air is what really eats into a budget.

“The air is where the little dollar bills fly out,” says Cairns, adding that two diesel compressors can consume a tanker truck of fuel every week.

The 1990s also saw more efficient snow guns come to market. Tinkerers discovered that devices with multiple small holes, instead of a single large aperture, could utilize water, rather than air pressure, to force fluid upward. This allowed them to move the compressed air nozzles to the outside of the barrel, where they would primarily break the water stream into droplets — a far less strenuous function than forcing them out of the gun.

“An old-school hog might use 800 cubic feet per minute [of compressed air]. This one here uses about 70,” Folts says, pointing toward a tower gun from the early 2000s that stands about 15 feet tall and, unlike the ground guns on Blue Ribbon, can’t be easily moved. Up the hill sits a newer model that can get by on closer to 40 cubic feet per minute, or CFM, and a bit farther down the slope is the resort’s latest tool, which under ideal conditions can use as little as 10. That’s a roughly hundred-fold increase in efficiency.

The state-backed Efficiency Vermont program urges resorts to swap in as many of the more efficient devices as possible. “That work got a real big boost in 2014, when we did the ‘Great Snow Gun Roundup,’” explains Chuck Clerici, a senior account manager at the organization. Before then, it had been doing a handful of sporadic replacements. The roundup retired some 10,000 inefficient models statewide, and, overall, Clerici says snowmaking operations are now using about 80 percent less air than they used to.

The president and general manager of Bromley Mountain Ski Resort sits at desk with a map of the resort and its snowmaking system.
Bill Cairns, the president and general manager of Bromley Mountain Ski Resort, with a map of the resort and its snowmaking system. Tik Root / Grist

While Efficiency Vermont doesn’t separate savings that are the result of snowmaking upgrades from, say, those tied to building improvements, it reports that its efforts to help ski resorts use less energy have saved more than a billion kilowatt hours of electricity between 2000 and 2022. That’s nearly a million tons of planet-warming carbon dioxide emissions or the equivalent of taking more than two gas-fired power plants offline for a year.

“The bigger projects we’ve had over the years have been snowmaking projects,” says Clerici. “We don’t have that many instances in the energy-efficiency realm where you can swap something that uses one-fifth of the energy.”

Standing next to the building that houses Bromley’s air compressors, Cairns points to a concrete slab with two manhole covers that once fed massive underground diesel tanks. “Underneath was fuel,” he says. To his right is a large pipe marked where the carbon-spewing generators used to connect to the rest of the snowmaking system. Now it’s cut off.


Bromley is among the many snowmakers that have been able to eliminate, or drastically reduce, its dependence on diesel air compressors. Electrifying the job has also allowed some resorts to incorporate renewable energy. Bolton Valley, in Vermont, features a 121-foot-tall wind turbine. Solar panels now dot the hills of many others, including Bromley, which leases a strip of land beside its parking lot for a solar farm. The array produces more than half the power its snowmaking system consumes.

America’s snowmaking industry has been historically based on the East Coast, where natural snow can be especially elusive. But that’s changing. “We’re doing a lot more work out West,” says Ken Mack, who works for HDK Snowmakers, one of the largest equipment manufacturers. One of the company’s executives recently moved to Colorado to help meet demand. 

The snow guns that HDK sells currently may be reaching the limit of how little water and compressed air they use. “We’re probably getting to a point where we’ve gone as low as we can go,” says Mack. That’s required finding gains in other arenas.

One step snowmakers can take, says Mack, is to better track how much energy they use, ideally in real time. He’s in the midst of trying to help revive a metric called the Snowmaking Efficiency Index, or SEI. It’s a measure of how many kilowatt hours it takes to put 1,000 gallons of water worth of snow on the hill, something Stanchek pioneered years ago but never quite took hold. (For reference, under ideal circumstances it takes about 160,00 gallons to cover one acre in one foot of snow.)

If publicly released, such data could provide transparency and allow ski areas to boast about their efficiency. That’s particularly appealing given that sustainability and environmental stewardship are increasingly top of mind for consumers. But because SEI varies considerably from mountain to mountain, and by temperature, it will likely be most effective as a tool for resorts to compete against themselves, rather than each other.

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This year, Bromley’s SEI ranged from about 23 in the warm, early weeks of the season to mid-teens when temperatures dropped. Cairns consistently tries to beat those numbers and can monitor them from his office. If the number ever spikes, he can search for an open gun, leaking water line, or other culprit.

“Anything below 20 is really good,” Cairns says. “So we’re trending the right way.”

An arguably more revolutionary development in snowmaking is the move toward automated systems that can be operated almost entirely remotely. One obvious benefit is reducing the need to find people willing to schlep around a mountain in the dead of night, when temperatures can dip into single digits. More importantly, automation allows resorts to ramp snowmaking up and down quickly, which is particularly useful as global temperatures climb. 

Snowmaking can occur when the mercury drops to about 28 degrees F (though the process is optimal at around 22 degrees or less); a threshold Mother Nature sometimes crosses for only brief periods. When it does, resorts can take advantage with a press of a button, instead of having to spend the time dispatching a crew out to fire up all those guns. The ability to operate in shorter time windows also means less energy is needed to run pumps and compressors — and get people up and down the mountain.

“You’re done sooner,” says Mack. Where it might take 100 man-hours to cover a trail, automation could cut that to 20 or 30. “It’s absolutely a savings. But it also gives you a little bit of reserve if you need it.”

Europe is far ahead of North America when it comes to automation, in part because governments have subsidized the daunting expense of running electricity and communication lines across a mountain. The cost of installing the technology can quickly run into the millions and, without subsidies, the benefits for American ski areas have been limited largely to smaller mountains in warmer climates, such as in the mid-Atlantic, where it is vital to surviving. But bigger resorts in snowier locales, including Stowe, Stratton, and Sugarbush in Vermont and Big Sky in Montana, have been testing the equipment.

“The future of snowmaking is definitely going to be automation,” says Cairns. “It’s just a lot of money, and nobody really wants to subsidize that yet.”

Bromley is testing one semi-automated gun that could avoid the wiring issue. It uses the existing compressed air supply to spin an internal turbine that creates just enough energy to run a small onboard computer. By monitoring the weather conditions, it can automatically adjust the rate of water and air flow to produce optimal snow.

“Those guns don’t need any power,” says Folts, as he finished adjusting the position of one gun and moved to the next. “That’s kind of another next level.” 

Until then, Folts and his crew lumber on into the night, one gun at a time.


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