Why are some coffee roasters switching to electric machines?


Around the world, many roasters rely on gas or electricity to roast their coffee. The type of energy used largely depends on the roaster’s equipment  – including drum and fluid bed roasters.

However, with demand for sustainable coffee continuing to increase, as well as soaring shipping and energy costs, roasters are looking for new ways to appeal to consumers and reduce their spending. One of these includes investing in electric roasters.

So how do electric machines work, and which factors do roasters need to consider when using one? To find out, I spoke to two coffee professionals who work with coffee roaster manufacturer Stronghold. Read on to find out what they had to say. 

You may also like our article on choosing a roaster for your coffee shop.

Roasted coffee beans cool down in the Stronghold S9X electric machine's cooling tray

Exploring different types of coffee roasters

In previous decades, gas was the most commonly used energy source for roasting coffee – no matter which type of roaster was used. Drum and fluid bed roasters are the most common types of machines, with both capable of roasting coffee to a high standard of quality, whether using gas or electricity.

But in recent years, there has been a greater focus on electric machines, which allow roasters to have much more control over different variables.

Amir Navid is the CEO and founder of Kühne Kaffee in Hamburg, Germany – a regional distributor of Stronghold roasters.

“Comparing an electric roaster to a gas roaster is like comparing a Tesla with an old diesel car,” he says. “When roasting using gas-powered machines, roasters often have to make a lot of adjustments to their variables.

“But nowadays, roasters have to spend a lot more time on marketing their businesses,” he adds.

Traditionally, roasters would have to pay close attention to a number of different roast variables, such as temperature and total roast time. However, with the recent rise of electric machines, which often champion automation, roasters are able to spend more time away from their machines and focus on other areas of their business.

“[In some countries], you may also need to own a special licence and a certain type of insurance because of the carbon emissions produced,” Amir says. “Moreover, you also need to account for the additional costs of installing pipes and an afterburner when using a gas-powered roaster.”

Green beans being roasted in the Stronghold S9X electric roasterGreen beans being roasted in the Stronghold S9X electric roaster

Why are more roasters using electric machines?

There are a number of reasons why electric roasters are becoming more popular. One example is the ever-growing demand for more sustainable coffee.

Now more than ever, consumers expect the coffee they buy to be more sustainable. And while a large part of this is centred around more transparency and traceability in the supply chain, sustainability also extends to coffee roasting, too.

Traditional gas-powered roasters can emit several pollutants, such as nitrogen oxide, carbon monoxide, and carbon dioxide. These gases are not only harmful to the environment, but they can have serious effects on human health if inhaled in significant volumes.

Furthermore, these roasters rely on fossil fuels (mainly natural gas) to operate, which are known to contribute to global warming.

As well as this, in recent months, we have seen the price of natural gas rise sharply as a result of the conflict in Ukraine and economic sanctions placed on Russia.

Naturally, this means that the costs of operating a gas-powered roaster have also spiked – tightening many roasters’ margins and forcing them to look for ways to reduce spending.

“Roasters are looking for opportunities to minimise the uncertainty around fluctuating gas prices, as well as the possibility of supply shortages,” Amir explains.

For roasters who use gas-powered machines, the equipment is typically connected to a shared gas supply, which may also be used to heat the workspace, among other things. 

This can also have an impact on the roaster. During colder months, for example, while the central heating is used more frequently, the pressure could drop in the roaster, potentially leading to less consistent roast profiles. 

However, with electric machines, roasters can largely bypass these issues.

Alex Lee is the North America Regional Representative for Stronghold. He explains how electric roasters, such as the automated S9X smart roaster, can work more efficiently and accurately than gas-powered models.

“Rather than manually controlling gas flow, the roaster can manage all of their variables electronically throughout the entire roast,” he says.

Over the past few years, automation and AI have become more widely used in coffee roasting. In essence, these technologies allow roasters to better replicate roast profiles and to improve data analysis and application, thereby also improving coffee quality.

“In theory, a roaster should be able to perform as well as the manufacturer claims it can,” Alex tells me. “However, other variables like the roasting environment, maintenance issues, and even the coffee itself can affect performance.

“When you use gas, no matter how precise the roaster’s electronic control panels are, the energy generation is still too volatile to [have a higher level of control],” he adds. “By using electric automated roasters, we are able to mitigate potential errors as much as possible.”

Amir Navid uses the touch screen on a Stronghold S9X electric roasterAmir Navid uses the touch screen on a Stronghold S9X electric roaster

Understanding how electric roasters work

For roasters to successfully transition from gas to electric roasters, they first must understand how the machines operate differently.

By far the most important factor to consider is the difference in heat transfer. In general, electric machines have more advanced heat transfer systems, which means roasters are better equipped to control a number of variables.

“Stronghold’s S9X electric roaster, for example, has a triple heat management system,” Alex explains. “This includes heat transfer through convection, radiation, and conduction, and the roaster can control all three methods independently of each other.

“This means you can develop roast profiles more purposefully, as well as having the ability to experiment more,” he adds. 

In theory, having more control over different types of heat transfer allows roasters to more precisely control a roast. This can help them get the best out of a given coffee, and maybe even unlock a new flavour profile entirely.

“However, there are a number of factors which can influence how heat transfers from the machine to the coffee, such as the size and density of the beans, as well as varying levels of sugars contained within the beans,” Alex says.

Ultimately, roasters need to account for these differences when developing their roast profiles in order to get the best results from their coffee.

Temperature stability is also important for roasters. The more stable and consistent the temperature inside the machine is, the more consistent the roast profile will be.

“Stronghold’s X-Series roasters include a ceramic band heater around the drum system,” Alex tells me. “Because of this feature, the roaster can actively and purposefully control the temperature inside of the drum, ultimately allowing for more control over heat retention and dissipation.”

Installation is also a factor to consider. With gas-powered machines, roasters need to make sure they have a gas line ready, or get a permit to fit one if they don’t.

However, with electric roasters, installation is significantly more straightforward.

“Of course, with any large piece of equipment, you need to account for the size of the space [to make sure it fits],” Alex says. “But with an electric roaster like the S9X, you don’t need to account for a gas supply – just a stable source of electricity.”

Stronghold's S9X coffee roaster in a coffee shopStronghold's S9X coffee roaster in a coffee shop

What are the other benefits of using electric roasters?

Besides having more control over heat transfer, electric roasters boast a number of other benefits. This includes a number of cutting-edge features, such as AI-powered technology and other automated systems.

For instance, Stronghold’s S9X X-Lens temperature sensor improves the consistency and accuracy of various different roast profiles by measuring and recording bean temperature, rather than air or drum temperature.

“You can roast a full 8kg batch to maximise your output with no compromise on quality,” Alex explains. “Moreover, Stronghold’s Square platform means you can manage and share roast profiles with different roasters who also use Stronghold machines.

“Because of its user-friendly interface, the S9X can be used by a range of coffee professionals,” he adds. “World Roasting Champions work with our machines, as well as less experienced roasters.”

Amir agrees, saying “The S9X’s AI technology makes it easier to operate, and the precision in making adjustments on this machine are much more accurate than with gas-powered roasters.

“You can achieve quality and consistent results with every batch,” he adds.

Ultimately, with the increasing reliance on technology when using electric machines, roasters are able to diversify and experiment with roast profiles.

“The increased flexibility with different heat transfer combinations allows roasters to be more versatile than ever before,” Alex concludes.

Green beans being roasted in the Stronghold S9X roasterGreen beans being roasted in the Stronghold S9X roaster

It’s clear to see why more and more roasters are switching to electric machines. Along with natural gas prices and a push to cut carbon emissions, more roasters are also looking to regain control over a range of different variables to get the best from their coffee.

It’s safe to say that in the years to come, we will more than likely see the uptake of electric roasters increase. Just how the technology will continue to develop, however, remains to be seen.

Enjoyed this? Then read our article on how to ensure batch-to-batch consistency when roasting coffee.

Photo credits: Stronghold, Kühne Kaffee

Perfect Daily Grind

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