STiR coffee and tea magazine

STiR coffee and tea 31 Coffee Roasting's Environmental Footprint Coffee roasting's environmental impact consists of several factors, such as en- ergy consumption, emissions, and waste generation. Coffee roasting requires high temperatures, about 180 to 250 o C (356 to 473 o F), typically lasting 10 to 20 minutes. Most roasters use natural gas or propane, which contributes to the emission of car- bon dioxide, carbon monoxide, volatile organic compounds, and particulate mat- ter. Some roasters use electricity as a fuel source, but depending on the source of electricity, there is still a sizable footprint, including emissions. Additionally, roast- ing produces solid waste like chaff and defective beans. The roasting process by itself is not a major contributor to the environmental footprint across the coffee value chain, accounting for only 2-5%. However, in the face of climate change and other en- vironmental disasters, steps need to be taken to reduce coffee's adverse impact on the environment, wherever and how much ever possible. Emission Control for Coffee Roasters with Electrostatic Precipitation The coffee roasting process produces a large amount of smoke. The smoke comprises particulate matter like submicron-sized coffee oils, smoldered chaff, volatile organic compounds like acetaldehyde and acrolein, carbon dioxide, carbon monoxide, nitrogen oxides, etc. These components are harmful not just to the environment but also to human health. Taking measures to purify the smoke produced during coffee roasting helps im- prove air quality while also reducing environmental impact. Common coffee roaster fume-treating technologies include catalytic oxidation, activated carbon adsorption, wet scrubbing, and electrostatic precipitation. Of these, electrostatic precipitation (ESP) offers not just high efficiency in removing particulate matter but also consumes less energy, effectively reducing environmental impact. "Conventional coffee roasting is wont to employ thermal afterburners to burn emissions, which can utilize extensive amounts of fuel," explains Suhas Dwarkanath, founder of Benki Brewing Tools and Specialty Coffee Academy of India. An ESP filter can substitute or supplement afterburners, drastically lowering the use of fossil fuels and carbon emissions. "An ESP filter can help achieve up to 95% reduction in particulate matter emissions, 20-50% reduction in volatile organic compounds, and 30-50% reduction in natural gas consumption (when replacing afterburners)," Dwarkanath adds. "If an afterburner con- sumes about 4 cubic meters of natural gas or LPG per hour, its ESP conversion would save up to 8-10 kg of CO 2 per hour of roasting. This would translate to a 10-50% CO 2 reduction in a year for a roastery depending on its size and operating hours." The Science Behind Electrostatic Precipitation Electrostatic precipitation (ESP) filters represent a highly effective approach to control- ling emissions in coffee roasting through a sophisticated yet elegant physical process. At their core, these systems work by creating an electrical field that ionizes airborne particles from the roasting process, giving them a negative charge. As these charged particles pass through the filter, they are strongly attracted to positively charged collec- tion plates, effectively removing them from the exhaust stream. The technology is particularly effective at capturing the fine particulate matter, smoke, and organic compounds released during roasting, with collection efficiencies often exceeding 99% for particles as small as 0.1 microns. The captured particles, in- cluding coffee chaff and submicron-sized oil particles, are then safely removed from the plates through automatic cleaning mechanisms, preventing their release into the atmosphere. ESP filtration is particularly effective at capturing the fine particulate matter, smoke, and organic compounds released during roasting, with collection efficiencies often exceeding 99% for particles as small as 0.1 microns. Infographic courtesy of Kleanland For roasters committed to both quality and environmental stewardship, ESP filters are not just an option–they are an essential ingredient in the recipe for a more sustainable coffee industry. Photo courtesy Manhattan Coffee Roasters ESP Filtration System for Coffee Roasters Roasting drum Cooling tray Green bean feed hopper Exhaust pipe KLEANLAND ESP Cleaned air Dust collector Baking exhaust gas Exhaust duct

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