Joel Glatz, head chef at Maine College of Art, has lots of options for filling his summer months, when the school’s kitchen is closed.

One year he worked as a summer camp chef. Another, he managed the general store on Great Diamond Island. This summer, he decided to go into business for himself by opening a food cart in Portland.

Glatz, 56, regularly parks his Yellow Cart (it has a big yellow umbrella) at a sweet spot on Commercial Street near DiMillo’s and Long Wharf, near pedestrian crossings and boat tour launches.

“All of those other jobs take me away from home and make me cranky and keep me indoors in a hot kitchen, and this is beautiful here today,” he said last week as he was busy making lobster grilled cheese sandwiches for tourists.

This has been a banner year for food carts and food trucks in Portland. The number of food carts in particular has exploded. The city has handed out 10 food cart licenses, more than double the number awarded three years ago.

“We get a lot of younger people applying, people in their early 20s,” said Janice Gardner, who works in the city’s business licensing department.

The number of new food trucks is holding steady at six – down four licenses from last year, but about the same as 2013. Still, that means there may be 16 new mobile food vendors roaming the streets of Portland this summer, selling products as varied as popsicles and Japanese street food. There’s now a total of 20 active food truck licenses in Portland, according to Gardner, and 23 active food cart licenses.

Talk to the owners, and they all have different reasons for being on the street. Some, like 27-year-old Ed Shevenell and 26-year-old Kari Williams, are using their cart as a stepping stone to something bigger. Both veterans of the restaurant industry, they own Snappy’s Tube Steaks, a gourmet hot dog cart that moves around via antique motorcycle.

“We definitely have aspirations to get a bigger food truck,” said Shevenell. “We just wanted to get our feet wet and experience this.”

Brendan Parsons, 26, owner of BP’s Shuck Shack, has experience working on oyster farms and in the catering business. He saw a lot of oysters being sold at festivals “but nobody was doing oysters a la carte.”

BP’s Shuck Shack was the first food cart in Portland that had to get an inspection from the Maine Department of Marine Resources. Parsons occasionally gets negative comments on the street from people who worry about buying raw shellfish from a street vendor, but he tries his best to set their minds at ease.

“I’m confident in my product,” he said. “The oysters that I’m putting out I know are fresh because I drive back (to Damariscotta) and get them. I know almost every grower in the Damariscotta River.”

Parsons is interested in expanding into catering weddings and other events. To that end, he was one of at least three new food vendors who pitched producers from the ABC show “Shark Tank” when they came to Portland last week.

Madison Gouzie and Eric Holstein, both 29, took their Marshmallow Cart to “Shark Tank” to see if they could get funding for their ultimate dream – a large fleet of food carts that could be used for private catering as well as street work. Their Portland cart, which sells toasted marshmallows and s’mores, is a summertime spin-off of a business they had in Brooklyn selling s’mores and hot chocolate during the winter.

Gouzie said it’s easier to get set up and do business here since the market isn’t quite as saturated as New York. “It’s a neat time to be building a food cart in Maine,” he said.