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Coffee’s carbon footprint

From the May 2020 issue.

Based on the calculation of the carbon footprint of a single cup of coffee, German roasting manufacturer Probat analysed and improved the emissions of its coffee roasting facilities.

With coffee a crop particularly vulnerable to changing temperatures, the consumption side of the supply chain is becoming increasingly aware of its own contribution.

“With people around the world walking the streets, fighting for a better climate, the industry can’t ignore its carbon footprint anymore,” says Oliver Böwing, Product Manager at German roasting equipment and plant manufacturer Probat.

When Probat turned 150 in 2018, it commemorated its sesquicentennial with the Connecting Markets Symposium. At the event, Böwing wanted to raise the industry’s role in climate change, and looked into the carbon emissions of coffee.

Several years earlier, German coffee chain Tchibo had released a report analysing the carbon footprint of the entire coffee supply chain, from growing the plant to brewing the beverage. It determined that a cup of coffee, brewed with seven grams of coffee and 125 millilitres of water, was responsible for 60 grams of carbon emissions.

“Before improving our own contributions, we have to understand what they are,” Böwing says. “For a product like coffee, which is not necessarily essential for living and can be considered a luxury, it’s even more important to understand how it can be improved.”

The report determined that coffee farming contributed to more than half of its total carbon footprint, largely due to the amount of water and fertiliser used in growing the plant. Coffee brewing factored in for roughly 30 per cent of emissions due to the energy used to heat water. Waste disposal, sales, and overseas transport totalled about 10 per cent (see Figure 1.)

“What was quite surprising for us is that roasting and grinding only had a 5 per cent share of that 60 grams per cup of coffee,” Böwing says.

“But I wasn’t sure what 60 grams actually meant, whether it was good or bad. I wanted to show the industry what 60 grams actually is in the grand scheme of things.”

To do this, Böwing looked for information on the carbon footprint of other everyday products. A 500-gram bowl of strawberries produces 442 grams of carbon. Ten rolls of three-ply toilet paper contribute 2500 grams. His 50-kilometre roundtrip to and from work totalled 5500 grams of carbon emissions each day.

“If you look at a bowl of strawberries, one cup of coffee is not a problem. In Germany, we drink about three or four cups per day and that is still way below their footprint,” Böwing says.
“All things considered, 60 grams of carbon may be a lot for a luxury item like coffee, but compared to something like transport, it’s still minor.”

While the report found that roasting and grinding contributed 3.18 grams of the total 60, Böwing felt that only factored in the actual roasting process and didn’t reflect the total emissions of a roasting plant. This inspired him and Probat to determine the total emissions of a complete roasting facility.

With Probat’s Jupiter 3000 roaster as a base, popular in industrial roasting, Böwing used a common European standard of calculating the carbon footprint of machinery.

He then incorporated the same data on green coffee silos, grinders, and roast and ground coffee storage. Through this, he determined the typical emissions of a facility in Germany powered by natural gas to be 2608.82 tonnes of carbon emissions in its first year of operations  (see Figure 2.)

Böwing says a shift in perception is needed within the coffee industry in order to make improvements to these emissions.

“We calculated the carbon emissions of steel support structures and compared it to wood. Wood actually results in negative emissions based on our standard, so that could be an option for roasters to consider,” he says.

“From a technical perspective, there is no real drawback to using wood. It just requires a change of mind of the industry building these facilities.”

Probat’s calculation factored in the emissions from the materials used in the construction of a facility. This means the figure would decrease in subsequent years, or if this was spread over multiple years.

“Especially with Probat, our facilities are quite long-lasting, so the material component is just a one-off contribution,” Böwing says.

“You can influence the carbon footprint of your materials, but this demonstrates that energy usage is what the coffee industry needs to focus on to reduce its impact.”

Geography and governmental decisions often limit a roaster’s control of the impact of their energy sources. Böwing says countries like Sweden, with more than half of its electricity generation being renewable – fare better than solid fuel reliant countries, like China.

In terms of gas, roasters – at an industrial scale in particular – have limited options to support their capacity. Böwing says natural gas is currently the best alternative, although better options could eventually arise.

“You never know what new developments could take place in the next decade,” he says.

“Hydrogen or biogas could be paths for the future. But these fuels will need to be created using renewable energy. Otherwise, natural gas will still be the best alternative.”

Recovering or reusing energy is one the best ways an industrial coffee roaster can improve its carbon emission. Probat has identified the three most viable ways it can help roasters in this regard.

“The roaster heats up air, makes the green coffee brown, and then afterwards, there is still a lot of heat left in the exhaust system that can be reused as energy,” Böwing says.

An air heat exchanger can redistribute hot exhaust air into other parts of or throughout the facility. Böwing says, for example, facilities in countries where a significant amount of energy is needed to heat up the building could use energy from the roasting system to do so.

Hot air leaving the drum could also be run back through the burner system to be reheated and used again for roasting. This recirculated air takes significantly less energy to heat than air pulled from outside the machine at room temperature. This technology is present in one of Probat’s newest machines, the Px 120 drum roaster, and is an alternative for smaller roasters also looking to improve their footprint.

The third and most complex – but possibly effective – option for industrial roasters is a condensate heat exchanger. This system uses water to absorb the heat energy from a roaster and transfer it to other systems in the plant.

“With a condensate heat exchanger, we can get about two thirds of the energy back to reuse,” Böwing says.

“We need to discuss this with the individual customers who run the facilities to determine where they can use this energy. Instant coffee plants, for example, have other equipment that uses a lot of low heat energy. That is something we can distribute from our system.”

While these are options Probat can offer to improve a coffee roaster’s emissions, roasters can take steps themselves to improve emissions.

“A roaster can have its equipment be state-of-the-art, not wait too long for upgrades, and use better or more efficient motors. This is important as burner technology in particular has really evolved in recent years,” he says.

Another way roasters can improve their emissions is to look at the products they produce. Dark roast profiles consume on average 13 per cent more fuel than conventional roasting. Böwing says this corresponds to more than 85 tonnes of carbon emissions per year.

“However, before a roaster can make changes to their products, demand needs to come from consumers, as in the end, you have to follow the market.”

For more information, visit co2.probat.com

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