Most nights after work, Andy Emerson and his wife, Sarah, are out harvesting.

The millennial couple aren't picking beans and peas in their garden. They're cruising city sidewalks, streets and alleys, picking up electric scooters for Lime, one of the companies that has a fleet of ride-share scooters on the streets of Minneapolis and St. Paul.

"Lime goes with unique terminology," explained Andy, 28, who works in operations during the day. "We say 'juicing' for charging, collecting is 'harvesting' and dropping them off is 'serving' them."

The Emersons are part of a sunset army of gig workers who retrieve thousands of depleted scooters, revive them, then drop them off all fired up for another day of zipping around town.

"It's a crazy business, but it's flexible," said Andy. "If we want a night off, we don't have to ask anyone. And if we work harder, we make more. I like that about this opportunity."

The couple also like the income stream from their side hustle. Andy calculates that they make between $4 and $8 for every scooter they pick up and power up. (The retrieval rate varies by time of day and the location of the scooters. Those that end up farther from the core cities or in hard-to-find locations yield more for the juicers.) They estimate they earned about $2,000 for July juicings.

The Emersons typically hop into their Ford Ranger around 7 p.m. Andy logs into the Lime app that pinpoints where riders have left scooters that have 20% or less of their battery power. He uses the app to reserve the scooters they intend to pick up, to avoid conflict with another juicer in search of the same bounty.

Andy typically gets behind the wheel, while Sarah rides shotgun. As navigator, she can also hold a spot while her husband double parks and jumps out to grab a scooter and put it into the back of their vehicle.

"I'm an efficiency nut. In this system, I'll be rewarded immediately when I find a way to work smarter," Andy said.

In a few hours, when they've collected between 10 and 20 scooters, they return to their century-old, two-bedroom home in northeast Minneapolis and unload the scooters into their fenced backyard. They plug the first 13 scooters into chargers connected to an outside outlet. (They've learned that any more than that trips their circuit.) The remaining two-wheelers tap into chargers powered by an extension cord plugged into a basement outlet.

"When I started, they gave me four chargers. As you do well and your metrics look good, they raise the limit. I went from four to eight to 12. Now I can have 50 in my possession, but we don't try to hit that," he said.

The couple sleep while the batteries rev up. (Andy said the increase in his electric bill is "minimal.") When the alarm sounds at 5:30, Andy loads the scooters back into his pickup. He estimates it takes less than an hour to drop the fully charged units at the locations that Lime directs.

The gig will be up as winter approaches, when the scooters will be warehoused until the snow melts. The Emersons will have their evenings back until spring.

In the meantime, they're feeling satisfied with using their earnings to pay down their debt.

"It's nice to spend time together doing something productive. We get out and see the city. We've learned more about the ins and outs of the neighborhoods than most people do in a lifetime. That's a fun perk," Andy said. "We're building our financial foundation, so we can get the life we want."