Denver floated strategies on Wednesday for meeting its big climate change goal, including pushing Xcel Energy to supply electricity only from renewable sources before 2030.

If these strategies are adopted, Denver would join Aspen, Boulder, Nederland and Pueblo among the more than 35 U.S. cities committed to using only renewable energy.

“We understand there are cities that want to do this, and we are going to do everything we can to help them achieve their goals,” Xcel spokesman Mark Stutz said. “We are trying to work with any city that wants to go 100 percent ‘renewable’ or 100 percent ‘carbon-free.’ We believe we can get electricity at equal or less cost with renewables.”

Xcel currently generates electricity from multiple sources — 46 percent from coal, 23 percent from wind, 25 percent from natural gas, and 6 percent from solar and hydropower. Xcel last week asked Colorado’s Public Utilities Commission to let it generate 55 percent of its electricity from renewable sources by 2026 (23 percent coal, 22 percent natural gas, 40 percent wind, 14 percent solar and 1 percent hydro), Stutz said.

There has been no electricity generated inside Denver using coal since Aug. 13, when the conversion of Xcel’s Cherokee plant to natural gas was completed.

Denver Mayor Michael Hancock has committed to an 80 percent cut in emissions of heat-trapping greenhouse gases including carbon dioxide, measured against 2005 levels, before 2050. Denver leaders say this will fulfill their pledge to meet the targets that nations including the United States agreed to in the Paris climate agreement — defying efforts by President Donald Trump to get the nation out of that deal.

“We as a city, along with other leading cities, want to be part of the solution,” Denver climate and greenhouse gas program administrator Tom Herrod said. “We owe it to our community to take action and there is a clear global threat from climate change.”

A city task force on Wednesday recommended the following strategies for meeting the goal:

• Make sure the city receives electricity only from renewable sources by 2030.

• Continue to shift to electric vehicles from those burning fossil fuels.

• Shift commercial buildings and 200,000 households off natural gas to heat sources that do not lead to carbon pollution.

City officials are seeking public comments on the strategies. They plan to fine-tune them before early next year.

Task force member Marc Alston, a former EPA employee, said residents must convert climate-change concerns to action.

“If you look at the projections for future temperatures in Denver and across the country, there are going to be areas that are very uncomfortable to live in and a lot of Denver residents are going to be very uncomfortable,” Alston said. “Scientists are correct in saying the time to act is now, not wait until it gets worse.”

But Denver’s population boom — state demographers project growth of 1 percent a year — complicates efforts to address climate change. More people would require more electricity and travel and produce more waste, all leading to increased emissions of heat-trapping gases. This pollution is degrading air quality, increasing an urban “heat-island” effect and contributing to extreme weather events and changes in mountain-snowpack melt.

At current worldwide rates of greenhouse gas pollution, Denver will face, in extreme years, 25 days where temperatures exceed 100 degrees, the city report warns.

Health officials anticipate continued rising temperatures could double heat-related deaths by 2050, with low-income, the elderly, children and infants most at risk. Denver now ranks third among U.S. cities for the worst heat-island effect with spikes of up to 23 degrees compared with nearby rural areas. Denver also ranks among the worst U.S. cities for asthma attacks and among the worst cities for ozone air pollution.

At the state level, Gov. John Hickenlooper also is pushing to faster action to address climate change. He issued an executive order in July compelling a greenhouse gas emissions cut before 2025 by at least 26 percent below 2005 levels and committing to the U.S. Climate Alliance of states and companies countering the Trump administration by shifting more quickly to wind and solar power.