Four years after President Barack Obama urged Americans to free the country from “the tyranny of oil”, Yalies and other Connecticut residents joined an estimated 12,000 demonstrators in Washington, D.C. to hold him to his campaign promise.

Twenty members from the Yale Student Environmental Coalition joined protestors who joined hands and encircled the White House Sunday afternoon, asking Obama to reject TransCanada’s Keystone XL tar sands pipeline, which would carry crude oil from Alberta, Canada to the Texas Gulf Coast. Yalies who attended the protest said they thought the demonstration was effective in relaying concerns that the pipeline poses environmental dangers, including increased carbon dioxide emissions and the possibility of oil spills.

YSEC President Sam Bendinelli ’13 called the demonstration “tremendously successful.” Prior to the event, he said protestors were unsure if there would be enough people to surround the White House block. But, he said, there were enough supporters to surround the block up to five times.

“It could not have gone much better,” he said. “I think this shows that the people who elected Obama still care about the environment, and so the President should too.”

Bendinelli added that cars and passersby reacted positively to the demonstrators — some vehicles honked their horns in approval.

One member of Yale’s contingent, Cynthia Deng ’14, was arrested after attending a similar protest in August. She said the demonstrators Sunday were a “very high-energy crowd” that continuously chanted and sang.

Still, the event was a peaceful one that resulted in no arrests, said Max Kushner-Lenhoff ’12, YSEC’s events coordinator.

The proposed pipeline poses an environmental risk because the extraction and refining processes associated with tar sands release three to five times as many carbon dioxide emissions as the extraction and refinement of conventional oil, Kushner-Lenhoff said.

He added that critics of the pipeline have also expressed concern over the potential damage an oil spill could wreak on the Ogallala Aquifer, which serves as a water source for millions of Americans in the Midwest. An oil spill would affect both the environment and water supply of the region, he said.

“We’ve seen issues that come out of reckless oil drilling such as the disaster in the Gulf and the Yellowstone River oil spill. If anything bad happens to the pipeline, it wouldn’t be the first time,” said Julie Botnick ’14, YSEC membership coordinator.

Justin Haaheim, lead organizer of global climate advocacy for the organization 350 Connecticut, led a group of 130 people, including Connecticut residents and Yalies not affiliated with YSEC, to Sunday’s protest. The goal of the protest was to increase awareness of the issue by making protestors’ presence known, Haaheim said.

“We’re doing everything we can to make sure that Obama can’t possibly ignore this,” he said in an interview Sunday afternoon before the protest.

Obama’s approval of the pipeline would demonstrate that promoting renewable energy sources is not one of the country’s priorities, Botnick said. She added that supporters of the pipeline seem to favor the independence resulting from a domestic energy source, but she views the proposed pipeline as both a “precarious source” of energy independence and a hazard to the environment.

Kushner-Lenhoff said the issue is a complicated one due to its divisive nature.

“There are people with interests on both sides, but I’m fairly confident that we’re on the right side of this issue,” he said.

Students from EnviroAdvocates, the environmental advocacy arm of YSEC, obtained 220 signatures on Oct. 7 after petitioning on Cross Campus. They presented a model Keystone XL pipeline made from ice cream cartons from dining halls.