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​59. Mashing without primary energy—The path to an autarchic brewery

Peter Gattermeyer, Krones AG, Freising - Germany

 

ABSTRACT: Brewing beer is an exceptionally energy-intensive process, and the brewhouse accounts for about a third of the energy used, made available as heat in the form of steam or high-pressure hot water and in the form of electricity for driving pumps and motors. Increasing priority is being accorded to downsizing the operating costs involved by significantly reducing the consumption of energy and media. In view of the lengthy lifetimes now being achieved by plant components, continually rising energy prices are compelling breweries to look far into the future when planning their investments. Moreover, social pressure and legislation relating to climate change will mean that new installations have to be chosen with a view to their CO₂ emissions. Today’s brewhouses achieve consumption figures of 6.2 kWhr/hL of cast wort cold for thermal energy, 3.0 kWhr/hL for electricity, and 1.4 hL/hL (1.4 US bbl/US bbl) for water. This development status constitutes the yardstick—one where any improvement seemed well-nigh impossible. The autarchic brewery, then, was thought to lie far off in the future. Thanks to a revolutionary design enhancement, the consumption of primary energy in the brewhouse, however, has been reduced by approximately another 30%. To achieve this, the production of superfluous hot water at the wort cooler is avoided, and instead, energy is recovered at a high temperature level in an additional heat exchanger stage. A pressure, less stratified, storage tank is used as a buffer between the energy source and the energy sink. This energy, in the form of hot water, suffices for heating the entire mashing process. The heating medium temperature here is only slightly higher that that the mash being heated. But, the requisite heat-up rates are achieved nonetheless. This is made possible by the specially shaped heating surfaces, which as pillow plates feature a cushion-shaped surface on the product side. This means that in mash kettles heat transfer efficacies hitherto unprecedented are being achieved, up to 100% above those of conventional heating surfaces. This invention enables alternative forms of energy to be efficiently deployed at a temperature level of <95°C (203°F). The very low heating medium temperature creates not only energy-economy gains, but technological advantages as well. Fouling in the mash kettle is avoided entirely, and the natural enzymes are treated gently. The thermal stress on the mash has been significantly reduced. Thanks to the reduced steam consumption in the brewhouse, new installations in particular can be designed with a smaller steam boiler and smaller steam and condensate valves. Now that less cooling output is required in the conventional stages of the wort cooling process, less iced water is needed too, which means that less electricity is consumed in producing it. This energy recovery system brings CO₂-neutral, media-friendly beer production within feasible reach.