Climate

It takes a lot of water and energy to make negronis, manhattans and margaritas. Could we do with less ice?

In the early 19th century, more than 100 years before electric refrigeration, an entrepreneurial Bostonian named Frederic Tudor landed on an idea: He'd cut blocks of ice from his Massachusetts lake and sell it to places where temperatures were too warm for ice to form naturally. Potential financiers thought this plan was too absurd to work. How would he ship the ice without it melting, they wondered, and who would buy it when it could be harvested for free?

Ultimately Tudor not only succeeded at distributing and selling ice—his trade revolutionized how Americans thought of food. Having access to ice enabled people to better preserve their meat and milk, reducing instances of food poisoning and launching the concept of leftovers. The initial desire for ice in warm places, however, wasn't driven by solutions to spoilage and illness: it came from bartenders. Tudor sailed to Cuba in 1815, where he found his first receptive market in the country's ubiquitous café culture. Cubans trusted their local baristas, each of whom had their own twist on café Cubano or a proprietary recipe for mixing crushed fruit with rum. Tudor demonstrated how to adapt those drinks into iced versions, and any initial suspicion of frozen-water chunks floating in glasses quickly turned into frothy demand. Five years later, when Tudor introduced ice to the bartenders in New Orleans's French Quarter, the alluring taste of chilled alcohol gave birth to the American cocktail culture we have today.

Ice not only cools cocktails; it changes their flavor, texture and balance. Shaking liquids with one-inch cubes, for example, aerates the alcohol and emphasizes subtle flavors, and it can also produce thick foams necessary for drinks such as the whisky sour. Crushed ice, meanwhile, dilutes cocktails quickly because of its high surface area, creating the refreshing, slushy consistency found in juleps that would taste too cloying otherwise. Bartenders in New Orleans went from serving simple, lukewarm drinks to inventing some of the country's most famous cocktails. There was the Sazerac, of course, in which the ingredients are stirred with ice to temper the burn of the high-proof rye and absinthe while melding the flavors. Henry Charles Ramos created his eponymous gin fizz in 1888 by shaking the liquids (including egg white and citrus) with crushed ice for a full 12 minutes, “until there is not a bubble left but the drink is smooth and snowy white and the consistency of a good rich milk.” In essence, ice transformed bartending from a mere job to a craft that involved creativity, chemistry and flourish.

Today even a moderately busy bar requires a lot of ice to get through a night. Bartenders are advised never to use the same cube twice when going through the steps of making a single cocktail: chilling glassware, shaking or stirring, and serving the drink. It's a process that requires a significant amount of water and energy. For years the hospitality industry has seen diners clamoring for foods that prioritize climate-friendly practices, such as local and seasonal ingredients that are grown or raised with carbon footprints in mind. Yet cocktail culture hasn't been hit with the same scrutiny. As the American West experiences water scarcity and energy prices remain volatile, the protocol for properly made cocktails doesn't look sustainable. Is it possible to make satisfying cocktails without so much ice?

Ice was, and still is, one of the most critical elements in a cocktail. In Liquid Intelligence: The Art and Science of the Perfect Cocktail, food scientist Dave Arnold explains how melting ice absorbs energy. In a cocktail, “there is no external heat source to supply the heat needed to melt ice, so the heat is drawn from the system itself,” Arnold writes. “As a consequence, the entire system chills.”

As any bartender will tell you, a cocktail flung back and forth over ice inside a shaker gets cold very fast. “The amount of energy you get from melting ice is phenomenal,” Arnold told me. Calculator in hand, he explained that if you shake three and a half ounces of tempered ice for 12 seconds, you'll generate about 2,000 watts of power on average. This amount is roughly the maximum load that can be safely drawn from a typical American home's electric outlet. “There's no real other way to ... extract that much heat from something as quickly,” Arnold said.

How much ice does an average bar use? According to Todd Bell, senior energy analyst at energy-efficiency consulting group Frontier Energy, the amount “really depends on the operation.” It might be between 200 and 300 pounds a night or far more.

“The ice-making procedure in bars is crazy wasteful,” Arnold says. “It's kind of just built into the way [bars] operate things.” Energy wasted from ice is largely because of in-house ice machines, which many—if not most—bars and restaurants use to maintain their steady ice supply. Ice machines run continually until they are full, potentially for several hours at a time. The machines vary widely in terms of the amount of energy they draw, however, depending on whether they are air- or water-cooled.

As the names suggest, air-cooled machines use air to transfer heat out of their systems, and water-cooled machines use water to do this. Well-maintained water-cooled machines are on average more energy efficient than those cooled by air, but they require much more water to produce ice. In nature, it takes only about 12 gallons of water to make 100 pounds of ice, Bell says. But water-cooled ice machines can require up to 100 gallons to produce 100 pounds, an amount so egregious that the U.S. Department of Energy's Federal Energy Management Program now restricts the installation of water-cooled ice machines except in buildings with cooling towers. Although air-cooled machines waste less water, many on the market still require more than 12 gallons of water to make 100 pounds of ice. In most cases, any unused water or ice at the end of the night is left to run down a drain.

Most bars aren't likely to give up ice altogether anytime soon. And cocktails aren't unsustainable just because of all the ice and water they require; they also tend to rely on ingredients that are shipped from far away, such as lemons and limes and liquors from around the world. But some bartenders are reimagining how ice and other ingredients can be used more sustainably. At Eve Bar in London, a new zero-waste menu includes cocktails made with leftover ingredients from its partner restaurant, Frog. The Bone Yard martini, for instance, uses vodka redistilled with venison bones to add a “bone marrow flavor” similar to what's found in some versions of the Bloody Mary. The technique is called a fat-wash because it lends the drink a savory flavor. “Whenever a dish [at Frog] changes, a cocktail [at Eve] changes,” says Adam Handling, the chef and owner of Eve Bar.

To mitigate its waste, Eve Bar forgoes an ice-making machine for 55-pound blocks of ice, which are delivered to the bar by a local ice company. Eve's bartenders precut the block ice to “fit perfectly” in every type of glass used, he says, so that no ice gets wasted. For cocktails that traditionally call for the use of crushed ice, such as tiki drinks, the bar uses liquid nitrogen instead. “We don't use crushed ice at all,” Handling says.

Jennifer Colliau is a sustainability-focused “cocktail nerd” who designed a bar menu that used as little ice as possible at The Perennial, a restaurant in San Francisco that closed in 2019. Colliau read about what Arnold has called the “science of shaking” and the “science of stirring” to devise ways to use less ice without affecting the taste and texture of cocktails. “Once you understand the role that dilution plays in drinks,” she says, “you can control it in different ways.” One method of eco-friendly cooling that she would never consider is whiskey stones, those small cube-shaped rocks made of soapstone or stainless steel that are sold as ice alternatives. “Whiskey stones are so stupid,” she says. “You can make the stones cold, and you can put them in your whiskey, but [because they don't melt] there is so little thermal transfer of energy that your whiskey won't get cold.”

To achieve dilution without ice, Colliau would measure a precise volume of water and add it to bottles of prebatched drinks that don't require fresh juice, such as martinis or manhattans. Juice will “oxidize over time,” she says, and “start to taste nasty.” This approach ensured consistency across her preassembled cocktails and eliminated the practice of throwing ice down the drain after shaking or stirring. Similarly, Re-, a bar in Sydney, Australia, serves most of its cocktail classics prediluted. “We never throw ice away,” co-owner Matt Whiley says. The bar's machine is set to create only what's needed, “so it's empty at the end of the night,” Whiley explains. Their drinks are made from food ingredients that tend to go to waste, including bread, dairy, bananas, rice and root vegetables. To serve those cocktails, Whiley uses ice carved from “off cuts”—slightly deformed blocks that his local ice-delivery company probably couldn't sell otherwise and would just let melt away.

When the same ice that is used to shake or stir a drink is used to serve the drink, it's called a “dirty dump,” explains Camper English, author of The Ice Book: Cool Cubes, Clear Spheres, and Other Chill Cocktail Crafts. “It's not a common move,” he says, because it can send bits of herbs or fruit into the drink, causing it to look “frothy, cloudier and chaotic in the glass.” The move should also be avoided with any drink requiring fizzy liquids such as soda water because “smaller ice fragments provide more nucleation points that flatten the [liquid's] carbonation and block the surface of the cocktail,” which prevents the tiny bubbles from rising out of the glass. But English actually prefers some drinks served this way, such as a mai tai or a margarita on the rocks, whose aesthetics and noncarbonated ingredients lend themselves well to the dirty dump technique.

Such resourceful approaches to bartending might signal the start of a shift—particularly for the U.S., where the ice trade was larger than anywhere else in the world. When Tudor launched his business more than 200 years ago, he probably never anticipated how consumed America would become with ice. Perhaps that's one reason ice is still somewhat rare in international cocktails. Consider the French Kir Royale, which consists of just black currant liqueur and champagne—it's almost always served neat. Or Hungary's Fröccs, which is made with soda water and wine and is “always served chilled” but “never over ice,” according to Afar magazine. Drinks in this style—refreshing but not frigid; based in spirits, liqueurs or wines made from local fruits and herbs—could be front-runners in an energy-efficient, climate-conscious cocktail movement.

This article was originally published with the title "Shake, Chill, Froth, Dilute, Discard" in Scientific American 329, 1, 82-87 (July 2023)

doi:10.1038/scientificamerican0723-82

The Ice Trade. October 28, 1868.

Amy Brady is executive director of Orion magazine and a contributing editor at Scientific American. She is author of Ice: From Mixed Drinks to Skating Rinks--a Cool History of a Hot Commodity (G. P. Putnam's Sons, June 2023). Credit: Nick Higgins

Kate Evans

Andrea Thompson

Martin J. Kernan

Jacob Job

Theodore Modis | Opinion

Karl Gruber, Lisa Melton and Nature magazine