When Nancy Kreitler saw an advertisement for Energy Day she knew where she wanted to take her grandchildren Saturday. Part of her reward was a strawberry slushy her 8-year-old grandson, Rhys Kreitler, produced using pedal power — a blender hooked up to a stationary bike ground the ice as the wheels turned.

Another reward was seeing Rhys, who’s interested in robotics, and her 10-year-old granddaughter, Tatum, excited about all the different exhibits by energy companies, museums and state and federal agencies on the grounds of Denver’s East High School. Down the street, teams of students rolled out their dueling robots, lining up to enter the makeshift arena in front of the high school’s main doors.

“They’ve done such a great job,” Kreitler said of the festival geared toward getting kids interested in science. “They really speak to the children at their level.”

Energy Day was billed as a family festival focused on STEM education — science, technology, engineering and mathematics. This was the second year the Consumer Energy Alliance and the Consumer Energy Education Foundation organized the festival in Denver. Houston is the only other city where the event takes place annually.

The Consumer Energy Alliance represents a range of interests in the energy industry, including small businesses, academics and conservation organizations.

“We’ve been doing the festival in Houston for seven years. It makes sense in Houston, being it’s the quote, unquote, energy capital of the world,” said Emily Haggstrom, the Consumer Energy Alliance spokeswoman.

And Denver makes sense as a location, Haggstrom said, because of the robust energy industry, from oil and gas to renewable sources. The area’s schools and universities and “all the great research institutions,” including the National Renewable Energy Laboratory in Golden, were a draw as well, she added.

A major goal of the events is to pique children’s interest early in the sciences and educate them and their parents about the career opportunities. The gap between the number of people needed for science, energy and engineering jobs and the number of people deciding on those careers is growing, Haggstrom said. In the energy field alone, federal figures project an upcoming demand of hundreds of thousands qualified people, she said.

Ascent Geomatics Solutions, one of the exhibitors at Energy Day, is looking at gaps as baby boomers retire, said Keith Hulen, the company’s director of business development. The company collects and analyzes geographic data for the energy and transportation industries, among others. And Ascent uses a fleet of 10 drones of varying shapes and sizes to gather data that used to be gathered mainly by land surveyors walking painstakingly over long distances.

“We’re able to collect a lot more data,” Hulen said.”And it’s safer. We don’t have to have people along the roadways.”

Surveyors don’t have “to be trudging through someone’s cornfield” when trying to get the lay of the land for an oil and gas company, Hulen said.

The hope is the changing technology, including the drones, which Ascent put on display for Saturday’s event, will attract young people who don’t necessarily want to spend their workdays outside.

“Our industry has to change if it wants to be able to attract young people,” Hulen said.

During Energy Day, Haggstrom said more than $6,000 of scholarships was awarded to students.