Green is more than a team color for the Philadelphia Eagles. By the end of the year the team's stadium, Lincoln Financial Field, will generate enough energy from 14 wind turbines and 11,000 solar panels to power every home game.

"One of the uses of such a high-profile enterprise is you can sometimes help show the way and lead by example," said Eagles Vice President of Communications Rob Zeiger.

Construction of the wind turbines was to be completed this week. The 15-feet-tall structures were installed atop the north and south ends of the stadium, in direct view of the nearly 70,000 fans entering the "Linc" and the countless drivers passing the complex on I-95.

A canopy of solar panels shields tailgaters in Parking Lot K from the elements with installation continuing around the exterior of the stadium's south side and above some bleacher seats.

"The Eagles have done a really great job of integrating renewables in a meaningful way," said Martin Tull, executive director of the Green Sports Alliance.

The Eagles aren't the only professional sports team implementing eco-friendly initiatives.

"Of the 126 professional sports teams in the five major professional North American leagues, 38 teams have shifted to renewable energy for at least some of their operations," "Game Changer," a September 2012 report from the Natural Resources Defense Council, said. With 18 of those 38 incorporating solar energy, said Darby Hoover, report co-author and senior resource specialist with the NRDC.

In January 2010, the NRDC worked with Seattle's Vulcan Inc. to form the Green Sports Alliance, a non-profit that acts as a liaison between sports organizations and environmental experts.

Vulcan is the company that oversees the business and philanthropic interests of Microsoft co-founder Paul Allen, who owns the Seattle Seahawks and the Portland Trail Blazers.

The alliance began with six professional sports teams: the Seahawks and Trail Blazers, as well as the Seattle Sounders FC, Seattle Mariners, Seattle Storm and Vancouver Canucks.

"We focus on five core areas: energy, waste, water, purchasing and transportation," Tull said. "We look at how those issues can be addressed at a facilities level."

The alliance now boasts 58 pro and collegiate teams as members.

Alliance members make a commitment to track their facilities' environmental performance and share that data with the nonprofit, as well as continually work to improve the venue's environmental footprint, Tull said.

There are no required standards to join the alliance, he added. "We didn't want to have a barrier to entry for facilities that were underperforming."

"The message is coming out of the league offices to the teams," Hoover said. "They would like to support environmental initiatives because it is the right thing to do. [The teams] feel a responsibility as cultural leaders in society."

But Tull admits there are other motivators, namely the bottom line.

"The reason that almost all of the teams have joined is they would like to know how the Seattle Mariners saved $1.5 million in the last year and a half by doing an LED retrofit," he said.

"There are some team executives and team owners that make [environmentalism] a priority," said Marc Ganis, president of SportsCorps, a sports business consulting firm. But marketing and branding are also important factors, he said.

As long as the results for the environment are positive, the organizations' motivations are unimportant, Hoover said.

Plus making a business more environmentally friendly is a lot of effort for marketing.

"You don't go green and just check that off your list," she said. "Going green is about a way of doing business that persists."

Due to the age, condition and location of the various venues, each faces different challenges and there is no universal solution, Tull said.

The initiative that works for Safeco Field, a 47,000-seat outdoor stadium with a retractable roof in Seattle, might not be as successful if implemented in Barclays Center, a 19,000-seat indoor arena in New York.

"The goal is to bring the fans into the initiative, to give fans an opportunity to participate," said Hoover. "How can we make this something easy to do and inspirational?"

For Safeco Field and the Seattle Mariners that meant creating "Sustainable Saturdays." Fans at the game could text answers to eco-trivia quizzes to win prizes. Compost made up of the stadium's food waste was a giveaway at games, too.

"When you have so many people paying attention to the team you want to make good use of that attention," Zeiger said.

Tull agrees, saying, "The people who can be reached through a values based plea are often people who already care about the issue."

Sports teams can reach an audience that has maybe not regarded environmental issues as a core value, he said.

"To have your favorite team, a big powerful brand in the community, say we think energy conservation is important, that is a really important trend that is under way."