Back when the days were still getting longer, Green Street Coffee added to their collection of equipment behind the counter at their corner space at 11th and Spruce. Next to a sink and air pot brew station, they found room for a kegerator topped with four taps. From the first three taps, they’re currently serving their house cold brew and manager Jeremy Behne’s chai tea (which they’re going to be bottling soon), as well as carbonated water.

The chai, one of their standard cold brews (blends and single origins that rotate in and out), and their nitro charged cold brew (the fourth tap) will be pushed through the lines with nitrogen which is ideal since it does not mix with liquids. The kegs themselves are conditioned with a 25/75 beer gas mix of carbon dioxide and nitrogen, which preserves the brews (by flushing out any oxygen).

Nitro cold brew at Green Street Coffee.

Early on, they were pushing the nitro cold brew through the lines with the beer gas blend. They switched that out in favor of 100% nitrogen after sharp carbonic acid notes from dissolved CO2 started creeping into the nitro cold brew. That was happening with that same 25/75 gas blend due to the near ten fold increase in pressure between conditioning (low PSI) and the line pressure (high PSI) for the nitro cold brew. That higher pressure, when coupled with the distinctive nitro spout, is what charges the brew and gives you the same cascade you expect with a Guinness. The desired result comes via agitation caused when the high PSI cold brew is pushed into the narrow holes of the nitro spout that acts as a restrictor plate.

But dialing in the right pressure and using the right gas or gas blend was half of the equation.

The guys at Green Street had to find the right coffees as well.

In the beginning stages, Philly Homebrew Outlet, who built their kegerator for them, did some trial-and-error runs for them.

“We tried the Kellensoo [single origin Ethiopian]. That didn’t work,” manager Jeremy Behne says.

The problem?

When you’re mimicking a stout, you don’t want bright fruit or acidity.

“Then we dropped off the Lupara before heading to a coffee conference in Maine and they called us and were like you have to try this. It was on point, so rich, creamy [which the nitro pour heightens], heavy, almost like what you want for a good stout. It’s rich, it’s dark, just a couple hints of some fruit notes just like our Lupara [coffee], but for the most part it’s very rich, very heavy,” he says.

The Lupara [Central American blend] works since it’s roasted a bit darker and has smoky, nutty, chocolate and slightly sweet cherry notes, says Behne, who has way more experience in coffee than me.

Green Street will be hitting up the guys from Brewery ARS for more advice this Saturday. They’ll be there serving [FOR FREE] a 6% stout that is “heavy on chocolate and roasted barley” from 1pm until the keg is kicked. It will take the place of the not-to-be-missed seltzer. You can drink the beer with coffee notes in between drinking the cold brew coffee that looks like, behaves (cascades), and has the mouthfeel of a stout. Thinks can get weird.

Roasted beans from Green Street’s Fruition Blend were added to this collaboration post fermentation along with vanilla, Sean Arsenault of ARS says. Green Street co-founder Tom Molieri says the blend, with less acidity and more complexity than a single origin, with a bigger, richer body, is perfect for a stout.

Sean and Andy Arsenault first met the brothers Molieri (Tom and Chris) through a meeting of local businesses set up by South Philly Food Co-op. “Besides wanting to use somebody local [Green Street roasts in South Philly, where they live], we drink their coffee all the time,” Andy Arsenault says.

Green Street just revisited last year’s collaboration with Iron Hill Voorhee’s Kevin Walter. When I spoke with Kevin Walter for this 2014 Philly Beer Scene brewer profile, he said with brewers expanding styles and looking to use higher quality ingredients, it only makes sense to go with better coffee that–for those new to craft coffee–transcends expectations.

So, instead of the burnt notes of your average French roast (La Colombe, Starbucks, etc.), you get the brightness of an Ethiopian Kochere (Yirgacheffe region) or Ethiopian Kellensoo (Sidamo region) that were respectively used in a brown ale collaboration last year and this year with Kevin Walter (you can get the current collab brew at both Iron Hill Voorhees and Media).

For anyone blown away by the collaboration, there’s the opportunity to repeat the process that ARS went through with Green Street. As part of their Kickstarter, which Foobooz detailed here, they’re offering the option, for $500 backers (6 of 10 spots remain), to design a coffee collab beer with them and Green Street. You’ll sit in on the roasting process and cuppings in search of the right coffee(s) ahead of making all other vital decisions for your beer. Just don’t put it in a bourbon barrel (overdone and unnecessary) or ad peanut butter notes (you’re an adult).

It’s been interesting seeing the progress of the nitro cold brew at 11th and Spruce. While Green Street never sold any that they weren’t happy with–as a regular, I watched them fuss over it and talk details with people from Philly Homebrew Outlet as well as bartenders from across the city–the process reflects the notion of always learning and improving that you’re exposed to if you sit at Green Street long enough. Since each iteration I tried was creamy with the right flavors (toffee and chocolate) usually there together following a beautiful cascade, I was never disappointed. As far as the fine tuning goes, they’re not alone–the staff (see my recent interview with Green Street barista and Top Hat Espresso Catering founder Tim Pearson) relates a visit to one shop where the “nitro tap”, perhaps temporarily so, was merely acting as a faucet, instead of delivering the desired cascade at hight pressure.

Speaking of always learning, Tom Molieri is trying his hand at home brewing with a sour beer that utilizes cascara, the dried fruit from coffee beans (I discuss it here with a new Philly coffee roaster).

For someone who interacts with people in every area of the food and drink scene, he says, “it helps me understand their craft better now,” he says of when he talks to brewers.”It helps me be a better decision maker as a consumer,” he adds.

I like to balance out with beer after drinking too much coffee. Tomorrow, I won’t have to leave the coffee shop to do so.

Note: Speaking of beginnings, check out my 2011 Philadelphia City Paper piece that covers Green Street Coffee’s origin story (you can actually see my byline attached to the story I wrote here ; it’s missing on the CP site for some reason; CP please fix).