On March 17, people across the United States and the world will once again celebrate St. Patrick’s Day. This holiday was originally meant to commemorate Saint Patrick and the arrival of Christianity in Ireland, though it ended up evolving into a larger festival commemorating Irish heritage and culture with people celebrating in a variety of ways: wearing green, eating corn beef and cabbage, and extolling their personal Irish ancestry (no matter how small a percentage it might be).

But in the Americanized version of St. Patrick’s Day, heading to the bar and drinking beer is one of the most visible traditions associated with March 17. This pilgrimage to the local Irish pubs is so ingrained in American culture that the excess amount that Americans drink on St. Patrick’s Day compared with an average day on the calendar can be reliably measured and analyzed. While brewers certainly enjoy the spike in sales, what does the increased beer consumption do to the collective energy consumption in breweries? While obviously the surplus needed for a known and expected spike in demand is built up in the weeks and months leading up to a holiday, I still thought it would be interesting to find out what the surge in U.S. beer sales would do to total energy use by breweries.

Disclaimer

I feel it necessary to preface this post with two disclaimers for two very different reasons.

Disclaimer 1: Even though the data analyzed here shows a substantial increase in beer sales in the United States on St. Patrick’s Day, please do not use that as an excuse to overindulge. While the holiday is certainly a fun excuse to throw on your green attire and head to the bar with friends, remember to drink responsibly and in moderation. More importantly, please remember to be safe and do not drink and drive. Alcohol-related car crashes claim a life every 46 minutes on St. Patrick’s Day and 32% of all traffic fatalities on St. Patrick’s Day are from alcohol-related crashes. So have fun, but be smart and be responsible.

Disclaimer 2: The data used in this article are the best estimates found in publicly available data and studies, and the math done is best seen as a set of back-of-the-envelope calculations based on that data. Surely there is variation from bar to bar, brewery to brewery, and region to region, but these calculations are meant to get into the ballpark and represent a good educated guesstimate at the answer to the question we’re asking. Also note that the data used is based on U.S. beer consumption, but the beers being sold also comes from imports, so the entire energy increase is not entirely contained to the United States (and we are only looking at the energy to brew the beer, not to ship and distribute to the final destination).

Calculations

To start with the calculations, we first want to find out how much more beer is sold on St. Patrick’s Day compared with the average day in the United States. St. Patrick’s Day is actually fourth on the list of days where Americans consume the most alcohol, behind New Year’s Eve, Christmas, and the Fourth of July. However what sets St. Patrick’s Day apart from those other boozy holidays is that the other days traditionally cause a dramatic increase in alcohol sales in stores to be consumed at home, while the bulk of the increase in beer sales on St. Patrick’s Day comes from bars and restaurants. This conclusion actually makes sense, as Christmas and New Year’s Eve are more associated with celebrating with family at home drinking champagne or wine, while on the Fourth of July you’re more likely to buy a case of beer and head to a backyard barbecue. However when you think of St. Patrick’s Day, you typically imagine droves of green-clad bar patrons crowding into Irish pubs and other establishments that are all too happy to pour the masses pint after pint of Guinness. For that reason, we’ll focus on the increase in beer sales at bars and restaurants on St. Patrick’s Day, ignoring beer sales in stores.

To establish a baseline of beer sold in U.S. bars and restaurants on a typical day, the National Beer Wholesalers Association reported that 206.7 million barrels of beer were sold in the United States in 2015. According to Census data, beer in kegs represents about 8.6% of all U.S. beer sales. While its true that keg sales do not go entirely to bars and restaurants, with some small percentage diverted to college frat parties or craft beer aficionados with kegerators at home, for the sake of this exercise we’ll assume that all kegs sold are for consumption in public establishments. So taking these two data points together, we can reasonably estimate that almost 18 million barrels of beer are sold each year to U.S. bars and restaurants, with an average daily rate of consumption of almost 49,000 barrels of draft beer. However, draft beer from kegs and barrels only accounts for a portion of beer sales in bars, as many customers also order beer by the can or bottle. In a study of data from BevSpot, draft beer accounts for about 61% of beer orders. Using this fact, we can say the total average daily consumption rate of beer (both draft and cans/bottles) at bars is about 80,000 barrels of beer (or about 19.8 million pints of beer). If that doesn’t sound like as much as you expected, consider that this amount of beer is equal to almost 10 minutes of continuous flow through the Chicago River that gets dyed green every St. Patrick’s Day.

Now that we have a baseline for an average day of consumption in American bars, how much more beer is sold on St. Patrick’s Day? According to SteadyServ’s analysis of their own data, 152.5% more beer is sold on St. Patrick’s Day than on a typical day. That figure amounts to an additional 122,000 barrels of beer (or 30.2 million pints) served in bars and restaurants on St. Patrick’s Day, so now we’re looking at a total of 24 minutes of flow from the Chicago River to make up the amount of beer needed for St. Patrick’s Day bar patrons.

To bring it all back to the additional energy required to produce this additional 122,000 barrels of beer, an energy usage report from the Brewer’s Association finds that it takes between 50 and 66 kilowatthours (kWh), on average, to produce a barrel of beer. This energy use comes from both electricity and natural gas usage, as broken down in the below graphic.

In the end, St. Patrick’s Day beer consumption accounts for an additional 6 to 8 million kWh, or 6 to 8 gigawatthours (GWh), of energy consumption compared with beer needed for an average day— see graphic at the end of the post for the full graphical walkthrough of these calculations.

Analysis

An increase in beer consumption that amounts to 6 to 8 GWh of required brewing energy is significant, and this figure does not even account for shipping costs (particularly for Guinness which sees an especially dramatic uptick in sales at 819% more than usual, with all Guinness Stout being brewed in Ireland despite other Guinness beers being made domestically). How can we contextualize this much additional energy for St. Patrick’s Day beer drinking?

The national average distance for an Uber ride is about 6.4 miles, so how many people who have been drinking at the bar can we send home in an Uber with this amount of extra energy? In 2018, the U.S. stock of light-duty cars has an average fuel efficiency of 23.2 miles per gallon, while the energy equivalent of a gallon of gasoline is about 36.6 kWh. These data suggest every Uber home would cost about 10 kWh and we could power a total of 600,000 to 800,000 Ubers home with the energy required to meet the uptick in U.S. beer consumption.

Massachusetts, the state with the highest percentage of its population claiming Irish heritage, consumed 2,039 GWh of electricity during November 2017. Based on this data point, the energy used to create the extra beer needed for U.S. St. Patrick’s Day consumption could power the entire state of Massachusetts for two to three hours.
What if, instead, some of those Irish-American citizens of Massachusetts decided to fly to the homeland and celebrate St. Patrick’s Day in Dublin, Ireland? Assuming Boeing 747 flights each carrying 500 people, using 5 gallons of jet fuel per mile and a kerosene jet fuel that contains 39.5 kWh per gallon, and a 2990-mile flight, the energy needed for the extra beer could send 10 to 14 flights from Boston to Dublin for a total part size of 5,000 to 7,000 people!

In short, that’s a lot of energy needed to fill the extra beer-drinking demand from a single holiday. However don’t take that as a need to not imbibe and enjoy St. Patrick’s Day, but if you want to offset the energy use (and the carbon footprint, which I didn’t even touch upon) then you can find creative ways. Choose domestic beers instead of imported so you can be sure less energy went into its transportation, identify breweries that use renewable energy (lots of good ones in this previous blog post of breweries using renewable power sources), or offset your increase in beer consumption on this one day by decreasing by the comparable amount the following week so your balance sheet comes out even (though I suspect the collective hangover post-St. Patrick’s Day might already be causing this effect on its own).

But in the end, enjoy the holiday, use the trivia in this article to impress people at the bar, and be sure to tip your bartenders well as they are probably the ones who are actually expelling the most increased energy on St. Patrick’s Day!

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If this article on the winter holidays and energy use/CO2 emissions appeals to you, check out my other holiday themed articles for Halloween, Thanksgiving, Christmas/Hanukkah/Kwanzaa, and New Years Eve.