... distance is only part of the equation; the mode of transport matters, too. For example, a recent study (PDF) by wine expert Tyler Colman and sustainability engineer Pablo Päster has gotten a lot of attention for proposing that people living east of an imaginary "green line"—which runs roughly through Kansas—would be better off buying wine sent by container ship from Bordeaux, France, then trucked to its final destination, than wine trucked all the way from Napa, Calif. That's due to the fact that container ships are generally considered cleaner modes of transport, which makes up for the longer journey. By the same token, shipping by rail rather than truck would push the green line eastward.
But maybe, you say, we should not have national beer brands at all. Maybe everything should be made locally. To evaluate that idea we would need to know whether the scale savings from the brewing offset the costs of shipping. That leads us to the third chart, which I found here, and which immediately takes us down the rabbit hole. Because once you start to work out exactly what part of the emission come from what, things get complicated. According to that study, the malting and production stages that the big brewers do so efficiently is only 14% of the total carbon emissions (this is for the UK, it's potentially large in the US). There's another 6% related to the growing of hops and barley (a significant chunk of which comes from producing the fertilizer). Unless your local brew uses organically grown barley, that portion, as well as the 11% the comes from producing the glass or can, is unlikely to be substantially more energy efficient for a small local a brewer. In fact, I would assume that because the packaging and ingredients themselves need to be transported to the bottling plant, the big brewers probably have an efficiency of scale in this respect as well. So, at least 14% and perhaps up to 31% of the emissions may be reduced by buying non-local beer brewed by a large manufacturer, and this reduction might save anywhere between 7% and 15% of the total emissions. On the other hand, the fully local plant requires less transportation, and this is 21% of the total emissions. So if everyone was home brewing, we could eliminate this part entirely. The other way to reduce this substantially is to drink only draught beer. Not only is the packaging less costly in this case, but it adds much less weight to the freight. Then you come to the final category of consumption related emissions, which in fact dominates the emissions spectrum at 47% of the total. This category is due to the refrigeration at home or at the pub, keeping the lights on in the pub or restaurant where you are having the drink, and driving to the pub. Naturally, none of this changes at all if you choose Local Lager instead of PBR. So, basically, drinking local beer is unlikely to make a major dent in the greenhouse gas emissions that beer drinking causes to begin with. If you really want to make a difference, try sitting at home in the dark drinking a warm barrel of locally fermented spit.
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