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Modern Process Equipment

Green Machines:
Roasting while protecting the environment

By Alexis Rubinstein

Ever since the world of coffee has joined forces with environment-conscious trends, many steps have been made to further advance the industry. Eco-friendly growing and organic beans were only the beginning. Now, coffee roasters have become available that reduce carbon emissions and conserve energy.

Hybrid cars, energy-saving fluorescent light bulbs—the crisis of our environment has become mainstream and a concern to most. While the coffee industry jumped aboard this train a while ago, it seems they are continuously looking for ways to create, contribute and conserve. Coffee pioneers have begun to think outside the box, or bag (of beans), and are finding innovative approaches to “going green.” It can begin in the fields, with a lack of harmful chemicals, continue through organic beans and finish with specially designed roasting machines. Some companies have even allowed their distribution methods to be affected, taking into account the way in which the vehicles that deliver their products add to the ecological quandary. Peace Coffee a specialty coffee roaster in Minneapolis, Minnesota has transitioned to “Peace Pedaling,” ensuring all of their coffee is delivered by a bike team or biodiesel van.

Alternative forms of energy have been researched and approved as superior ways to power coffee roasters. Companies like the Vermont Coffee Company, who also participates in biodiesel van distribution, hopes to one day convert their coffee roasters to biodiesel energy. Solar power has been proven successful at running coffee roasters and new technology is constantly being created to cut down on energy usage.

Two Brothers, One Big Idea
Brothers David and Michael Hartkop of Solar Roast in Pueblo, Colorado were responsible for brainstorming, erecting and utilizing a solar powered roaster, but had never seen themselves as “inventors.” Michael worked at the Borders Café throughout college and eventually took a job (and completed an apprenticeship) at Mellelo Coffee Roasters. Afterwards, he went to Tasmania to attend a university and worked at a coffee and wine bar. It was here that he started demanding a better cup. After working in the film industry, David moved back to his home state of Oregon and enrolled in science courses at a community college. His interest in solar energy grew, as did his desire to create an experimental solar powered machine. After Michael returned back to Oregon from abroad, he combined his passion for coffee with his brother’s scientific initiative and the idea for the first Solar Coffee Roaster was born. “I think it was a little after we had the idea before we realized how appealing this sort of coffee might be in this climate of increasing eco-awareness. This was a couple of years before the gas prices shot up and energy issues weren’t really in the forefront of the public mindset at the time,” recalls Dave.

To turn this dream into a reality would be a difficult feat. David and Michael were now faced with the seemingly impossible task of constructing a working and efficient piece of equipment. “I think that preparation for something is tough to actually do,” explains Mike. “When an idea strikes, and a passion for something new begins, it is tough to hold off and say ‘I’m going to the library to research.’ The way I see it, if you like something and want to do it, just make it happen. We had an old satellite dish and the means to make over a hundred mirrors, so we did. Our neighbors all chipped in with pieces of metal and other objects that we needed.” The satellite dish was covered with silver mylar mirrors for the solar concentrator and a broccoli steamer (a stainless-steel cylinder with holes in it) as a make-shift coffee roaster drum. David pieced all the parts together, learning to weld in the process, using automotive motors and batteries, powered by a 45-watt solar panel, which was borrowed from a friend. The first time it was ever tried in full sunlight (about three months after the start of construction), the temperature rose to 600? F inside, and over 1,200? F on the outside of the aluminum housing, which promptly melted! One unsuccessful attempt was not going to diminish the determination of David and Michael. For their second try, the aluminum housing was replaced by a stainless-steel bucket which was then insulated with fiberglass, wrapped and contained in layers of aluminum foil and flashing. The roaster worked and produced, according to David and Michael, some of the “best bags of coffee anyone had ever tasted.”

Once they were able to overcome the obstacle of creating the machine, another problem arose—the weather. But all the determination in the world could not persuade Oregon to welcome the sun. “We moved our operation out from under the cloudy Oregon winter skies and into the sun in Southern Colorado,” says David.

How and Why it Works
Before any coffee can be roasted, the roaster must be aligned with the sun for the “charge phase.” At this point, the roaster is being heated and prepared for use. Generally, it takes 45 minutes to an hour to get the roaster to the ideal temperature. The beans are then simply poured in and roasted for 16-22 minutes, depending on the type of coffee and style of its roast. Mike elaborates, “This time period was chosen to create the desired roast profile. We could heat the roaster up hotter to speed things up, but who really likes charred coffee?” Temperature is well controlled throughout the process and the heat can be cut-off or slowed in several ways, including taking the alignment of the sun’s focus off, which is equivalent to turning your burners from “high” to “standby.” To force a pop on the coffee, fresh air can be blown over the beans. “Ventilation is such that I can control the airflow in the roaster to either recycle or bring in fresh,” explains Michael. After the beans are roasted they are poured out and cooled in a conventional style.

The Helios 3 solar roaster (the latest edition thus far, although a Helios 4 is in the works) uses solar energy in place of a traditional gas burner. The 6kW solar concentrator produces about as much heat as a small shop roaster (20,000 BTU/hour.) “At this rate,” says Dave, “our current roaster prevents about 5,500 lbs/year of carbon dioxide from being released into the atmosphere.” “The Helios 4 will have a power of 70,000 BTU and will operate much like a commercial 14kg drum roaster. It will prevent the release of over 38,000 lbs/year of carbon dioxide.” (Based on average power consumption per unit coffee and 2006 U.S. department of energy average of 1.55 lbs/kWh provided by natural gas.)

A Bright Future
“As it turns out, “ David comments, “the sun is a wonderful source of energy for real industry and actual commerce.” In the beginning of 2007, David and Michael Hartkop opened their first coffee shop, “Solar Roast Coffee” in Pueblo, Colorado. They are currently shipping their coffee throughout the U.S. with hopes of opening more cafes. Intentions on selling their coffee to organic food stores and getting national distribution are also present. With the success of the “backyard” version of the Helios solar roaster, a slightly larger roasting system is set up in a transparent dome at a separate industrial lot in Pueblo. “As long as the sun continues to shine, there will be coffee. And as long as there is coffee, there will be one happy coffee roaster here in Pueblo, Colorado,” concludes Michael.

On A Slightly Smaller Scale
For those of us unable or unwilling to create a solar roaster in our backyards, Probat offers an easily accessible way to conserve energy and reduce emissions when roasting coffee. The Probat Neptune 1500 was designed for gentle long run roasting, has optimized processing technology and a modern and energy-efficient operation. “In times in which climate change has moved into the center of public debate, Probat’s foresighted development is confirmed with respect to the environmental technology applied. With the new Neptune 1500, industrial roasting companies can increase productivity and simultaneously reduce the emission of harmful substances…” says Christian Beckmann, head of production management.

This “eco-friendliness” is especially evident in roasters with integrated re-circulation. The use of generated heat in the Neptune 1500 was optimized through the use of an anticipatory burner technology, as well as through the application of the re-circulating technology (ensuring the roasting gases are re-circulated throughout the process.) This enables a major part of the roasting gases to be fed back into the burner so that heat energy is used more effectively. Additionally, less fossil fuels are needed to be applied for energy generation, greatly helping the future of our atmosphere. According to Probat, “It is possible to significantly reduce emissions further when using Probat’s exhaust air cleaning system, Ecologist Proforte (a flameless technology characterized by low energy input), or alternatively, its catalytic converter systems as add-ons.” The possibilities for saving energy ranges from the more complex components such as the catalytic converters or heat exchangers designed for industry, to simple and low-cost measures, ideal for shop roasters. According to Probat, “these measures offer substantial savings potentials: implemented on a stand-alone basis, each measure can yield energy savings of 5-40%, while in combination the yield can reach up to 70%. Some of these measures also generate performance increases.”

Green is the New Black
The roasting phase is arguably one of the more important processes in the coffee industry. While the emissions they release (including carbon monoxide and carbon dioxide) are unavoidable, an oxidizer, or afterburner, can help to cut-down these harmful compounds. With this information, companies have begun to explore more environmentally sound options. Diedrich Roasters, based in Sandpoint, Idaho, offers a more energy efficient afterburner. The IR-Series Catalytic Oxidizer uses 65% less energy than a conventional model, according to the company. The IR-Series also features less fuel usage and lower operating temperatures—both effective steps in conservation. According to the company, Batdorf & Bronson Coffee Roasters has been purchasing 100% of their electricity from renewable resources since 2000. Additionally, solar energy is used at their Olympia, Washington roastery, among other sustainable business practices. Their concern on the matter is evident through their involvement in the U.S. Environmental Protection Agency’s Green Power Program, among other eco-foundations. Quality and efficiency do not need to be affected in order to partake in helping the environment. Producing a premium bag of coffee safely and cleanly is now much more than an aspiration, it’s a reality.

Probat’s 10 Measures
Trying to impart their knowledge and educate their customers, Probat has composed a list of 10 measures that can produce energy savings in the roasting process.
  1. Optimize roasting parameters “energy consumption,” “performance” and “product quality.”
  2. Use thicker and higher quality surface insulation. Energy savings = up to 5%
  3. Preheat burner air to 250?C via a heat exchanger. ES= about 8%
  4. Install a frequency converter to regulate the roaster fan. ES= about 8%
  5. Re-circulate roasting fumes. ES = up to 30% (can reach 40% if system is low-temperature.)
  6. Install a low-temperature catalytic converter. ES = up to 30% vs. standard catalytic converters.
  7. Install a heat exchanger to harness external heat. ES = up to 30%
  8. Install a heat exchanger in the process loop. ES = up to 30%
  9. Preheat green coffee to 80?C-100?C (only possible with batch roasters.) ES = up to 20%
  10. Install the Probat Ecologist Proforte exhaust air treatment. ES = over 50% vs. a catalytic exhaust air treatment.


Tea & Coffee - September, 2007
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