How heat pumps can turn wasted energy into low-carbon whisky

You can’t make whisky — or vodka or gin or any other liquor — without generating some heat. The heat required to produce the billions of liters of liquor consumed each year typically comes from fossil fuels, and much of it ends up as wasted energy.

But carbon emissions penalties in Europe and government incentives in the U.S. have nudged liquor producers in each region — and companies across the food and beverage spectrum — to begin embracing new technologies that can lower their carbon emissions. 

Take the Glentauchers distillery in Speyside, Scotland, one of the many producers of Scotland’s top food and drink export, Scotch whisky. Glentauchers opened in 1897, and its primary production method hasn’t changed much in over a century: It burns fossil fuels to boil grain mash in giant copper pot stills and distill the rising alcohol vapors. 

But the technology available to capture and reuse the heat lost via this type of traditional process has changed quite a bit. Rising energy costs and climate change have provided good reasons for distilleries like Glentauchers to try to make use of that tech. For its part, Glentauchers is harnessing a simplified version of heat-pump technology to harness the waste heat generated by its old processes — and to slash carbon emissions. 

“The waste-heat recovery resource that’s collectively available across industry is staggering,” according to Blaine Collison, executive director of the Renewable Thermal Collaborative, a global coalition of companies and organizations working to decarbonize industrial heating and cooling. The collaborative has been publishing case studies on a number of innovative projects, including the project at Glentauchers.

In a September report, the Renewable Thermal Collaborative found that heat pumps are already cost-effective for the low-temperature industrial heat processes — those using heat at less than 130 degrees Celsius — that make up roughly 30 percent of U.S. industrial thermal energy. ​“The food and beverage industry is dominated by the low-temperature stuff — and the food and beverage industry is a top-five emitter,” Collison said.

The readiness of this tech is good news for food and beverage companies, as the pressure is mounting to reduce carbon emissions. Chivas Brothers, the Scotch whisky business of French spirits giant Pernod Ricard and owner of Glentauchers, has set a goal of ​“carbon neutral distillation” across its production sites by 2026. 

The heat pump–adjacent tech cleaning up Scotch whisky

Chivas Brothers’ £60 million ($76 million) decarbonization plan is built on the heat-recovery project it launched at Glentauchers in 2021. The facility still relies on fossil-fueled boilers, but its new system has cut the distillery’s total energy usage by 48 percent and energy-related carbon emissions by 53 percent by reducing how much it has to use those boilers, according to the company’s case study.

The core technology at play in this energy-saving and carbon-cutting project is a mechanical vapor recompression (MVR) system designed and built by German company Piller Blowers and Compressors. In essence, MVR systems take vapor that’s not quite hot enough to do work needed in an industrial facility and use electrical energy to compress it, heating it up to the required temperature. 

In that way, MVR is a ​“heat pump–adjacent” technology, said Caldwell Reed, vice president of sales and project management at Piller TSC Blower, the U.S. subsidiary of Piller Blowers and Compressors. 

Heat pumps use a four-step process of compression, condensation, expansion, and evaporation to increase the temperature of a vapor or fluid in a continuous set of pipes where heat is desired — that’s the heating side of the process. For the refrigeration or air-conditioning side of the process, the machines do the opposite — they decrease the temperature. 

MVR doesn’t include all of those steps, Reed said. ​“We are essentially just the compression portion. But we’re like a heat pump in the sense that heat that’s not usable, we compress and make usable again,” he explained. ​“Recently we’ve been getting a lot more, quote, ​‘heat pump’ requests, like those at Chivas Brothers.” 

The previously underutilized waste heat at the Glentauchers distillery comes from the alcohol vapor rising from its pot stills, which look like giant flasks with tubes at the top that curve and slant downward. Alcohol boils and vaporizes at temperatures well below the boiling point of water, which allows it to be separated from the grain mash, a beer-like liquid. That alcohol vapor ​“goes up and down that slanted tube, and then goes into a condenser and becomes liquid again, and moves on in the process,” he said, eventually becoming whisky. 

At that point, ​“the vapor coming off their pot stills has a lot of thermal energy in it,” Reed said — just not enough energy on its own to power the rest of the distillation process.

“The alcohol vapor coming off the pot still is at about 86 degrees Celsius, but what you need to drive distillation is 106 degrees Celsius,” he said.

With the new MVR system, that would-be waste heat is captured in a shell-and-tube heat exchanger, in which hot vapor carried within interior tubes is condensed, transferring heat to an outer set of tubes carrying vapor or liquid that can make use of the beefed-up waste heat. 

That heat hadn’t previously been going completely to waste at Glentauchers. Since the 1980s, the distillery has used a combination of hot-water condensers and thermal-vapor recompression, which is ​“essentially a way to mix low-pressure and high-pressure steam to make medium-pressure steam,” Reed said. 

But that process still requires an external heat source to make the steam that enables the recovery — and at Glentauchers, that heat source was oil-fueled boilers. By using electric-powered compression to boost heat instead, the Piller MVR system allows Glentauchers to ​“use way less steam to run the process,” he said. 

It also uses way less energy overall. According to the Pillar case study of the project, the system has allowed about a megawatt of heating energy going into each pot still to be replaced by about 90 kilowatts of electric power. 

That efficiency is due to the nature of using compression and expansion to transfer heat from one place to another, rather than burning a fuel to generate heat directly. That’s the fundamental distinction that makes heat pumps much more energy-efficient than fossil-fueled boilers and furnaces — a fact that’s making heat pumps an increasingly popular choice for new home and building heating systems. 

Similar dynamics have driven a small but increasing number of industrial firms to choose heat pumps as an alternative to fossil-fueled boilers. MVR systems like Glentauchers’ can be even more efficient than a standard heat pump that draws from the air around it. That’s because MVRs use waste heat as their input rather than ambient air, and it takes less energy to bring this pre-heated vapor up to temperature.

For heat pumps, that efficiency is measured as a ​“coefficient of performance,” or COP — the heating energy output as a ratio of the electrical energy going into the work they do. Fossil-fired or electric-resistance furnaces or boilers, which use energy to make heat directly, can never achieve a COP of greater than 1. High-performing heat pumps working from ambient temperatures can achieve a COP of 3 to 4. 

But the Glentauchers MVR system is achieving a COP of 10 to 12, which means, ​“for every kilowatt of electric energy going into the system, it’s sending 10 to 12 units of thermal energy back,” Reed said. 

From pilot projects to wider deployments

The fundamental technologies at play at Glentauchers could yield similarly dramatic energy and emissions reductions across a variety of industries, said Collison of the Renewable Thermal Collaborative. 

Waste-heat recovery is a key step in making the most of heat-pump technologies, given the energy-efficiency benefits that can be gained from reducing the gap between input and output temperatures. As Collison put it, ​“You’ve got this temperature resource. Why wouldn’t you grab it?” 

Reed named other industries well-suited for MVR, ranging from food drying and milk evaporation to ​“wastewater treatment, where you’re distilling water to make it purer.” Essentially, most ​“thermal separation processes requiring a lot of steam” can be made more efficient by using waste heat. 

Collison highlighted a number of U.S. industrial food and beverage facilities that are undertaking process-heat decarbonization projects. Some have been built from scratch to use electricity in lieu of fossil fuels, like the carbon-neutral whiskey distillery built by alcoholic beverages giant Diageo North America in Lebanon, Kentucky, which was designed with electrode boilers in place of fossil gas–fired furnaces.

To become truly emissions-free, industrial heating will ultimately need to drop fossil fuels entirely. That could be accomplished by electrifying heating with an increasingly clean-powered grid or by turning to alternative fuels such as biogas or green hydrogen. But that’s simpler to do in a facility purpose-built with that end in mind, Collison said. Unfortunately, purpose-built projects are not the norm. 

“The whisky distillation industry has a lot of legacy facilities,” he said. ​“Decarbonizing the world’s industrial footprint mostly means going back and doing retrofits,” which entails finding cost-effective ways to renovate facilities that can’t bear the cost of long shutdowns. 

That’s where policy could step in and help. 

“Government incentives — or disincentives — definitely impact these projects,” Collison said. ​“In regions of the world where there’s a government incentive to reduce your carbon emissions, or a carbon-tax penalty, there’s a lot more interest in systems like this.” 

That’s the case in the U.K. and the European Union, where companies face various mandates to cut carbon emissions and must pay for the carbon they do emit under emissions trading systems. European companies also pay much more for fossil gas than do their U.S. counterparts, which helps make the economics of switching to electricity more attractive. 

In the U.S., industrial decarbonization has primarily been driven by incentives rather than by penalties. 

Earlier this year, the U.S. Department of Energy awarded $6 billion in grants to demonstration projects aiming to slash emissions from a host of industrial sectors. Those grants included projects targeting more challenging high-heat processes like steelmaking and cement production.

But they also included about $500 million for a half dozen companies planning to deploy a range of low-carbon industrial process-heat technologies, including Diageo, which will use thermal energy storage at its Kentucky distillery, and Kraft Heinz, maker of ketchup, macaroni and cheese, and other grocery-store staples, which will install heat pumps, electrode boilers, and other technologies at 10 facilities. 

For its part, Chivas Brothers has not shared financial details on its project at Glentauchers, such as how energy savings will help it pay back the capital costs or lost production costs involved. But in general, the economics of waste-heat recovery and process-heat electrification are increasingly attractive in markets where electricity is a cost-effective substitute for fossil fuels, Reed said. 

“A lot of these projects are just economically viable in their own right, depending on the cost of electricity and the cost of whatever energy they’re using to run their boiler,” he said. And now, with more government incentives in place, these emissions-reducing projects are only growing more appealing.