Barista Magazine

APR-MAY 2018

Serving People Serving Coffee Since 2005

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T h e B a s i c s E s p r e s s o M a c h i n e s E n e r g y e f f i c i e n c y a n d h i g h e r f o r m a n c e a r e o t n e c e s s a r i l y m u t u a l l y e x c l u s i v e . S SPECIALTY-COFFEE PROFESSIONALS, most of us pride ourselves on being social and environmental stewards. We cultivate gathering places where people share their lives and connect with one another. We support fairly compensating the people who produce the crop that is fundamental to our own livelihood because we, too, wish to be fairly compensated for the work that we do. Personally, I am employed by a coffee roaster that roasts primarily certified-organic beans and uses compostable cups, lids, and cutlery. Social and environmental responsibility is very close to our hearts. It truly does mean more to us than just a sound bite. We meet the farmers, advocate for fair pricing, and have fundraisers to help support them keep up with rapidly evolving higher standards of production. When we think of it this way, it's difficult to imagine that as an industry we would turn a blind eye to the environmental impacts of energy use in our own cafés. As purveyors of specialty products, we rely on high-performance machines to operate at very high levels. As in the world of high-end race cars, however, often the highest-performing machines in specialty coffee are in fact the most energy consuming. Heating water is at the foundation of our lives as coffee professionals. To reach Specialty Coffee Association (SCA) Gold Cup standards, water temperature at the point of contact with coffee is recommended to be at 200°F +/- 5°F. In coffee brewers and hot-water towers, water must be kept at this temperature at all times. When we talk about coffee equipment in our industry, temperature stability and recovery time are the two most important concepts. In order to obtain an even extraction, the temperature of the water should be consistent as it is dispensed onto the coffee grounds, be it in an espresso machine or a coffee brewer—that's temperature stability. As the coffee equipment uses water, it is then filled with more water from the water line, which then must be quickly heated up to 200°F. How quickly a machine is able to reheat water is referred to as the recovery time. This all means that the heating elements in coffee equipment are constantly working to keep that water temperature at a sustained 200°F. Espresso machines get up to even hotter temperatures. In order to create enough steam and pressure for adequate operation, the steam boiler reaches temperatures upward of 260°F. This is the baseline of what needs to be accomplished with coffee-brewing equipment: heating water as hot as it can be heated and then keeping it there all the time. Simply based on the laws of physics, it takes a certain amount of energy to heat water to 200°F, so ultimately what we're looking to do when we talk about energy efficiency in brewing equipment is prevent as much heat loss as possible once we get the water up to that temperature. There are a few ways to address the problem of heat loss. One is to really be conscious of how you mount the tanks in the machine so that they are less able to transfer heat through conduction in the metal mounting brackets. More notably, heat loss is reduced by insulating the tank. This can be as simple as using a rigid fiberglass panel (which works OK) or Styrofoam (which is better but still not phenomenal). You might be surprised looking inside most coffee brewers and espresso machines: Oftentimes there is very little insulation in coffee brewers and none in espresso machines. Espresso-machine manufacturers have also found that adding insulation to the boilers means that the cups don't get as hot, so then you have to add an additional cup-warming system. There's an argument to be had that the "lost" heat from an espresso-machine boiler is providing a secondary function via heating the cups—but that heat is also radiating to other parts of the environment, and isn't actually serving a useful function outside of normal business hours. There are many heat-exchange espresso machines on the market that use only one water boiler. This single boiler heats the steam to around 260°F. The brew water is heated by running the brew-water tubing through this single boiler in a system known as a heat exchanger. As the brew water travels through the tubing that is moving through the steam boiler, it gets very hot, and can then be used to pull a shot of espresso. One boiler is able to heat two things at once—no separate water boiler is being used to heat the brew water. It really is an ingenious concept. If you didn't know any better, you might think that this technology is the future, but in reality, a single-boiler heat-exchange machine is often the less coveted style of espresso machine because you n d n ce a e t p n n ecessa l y m u t u all y 118 barista magazine

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