Aspen's overall energy mix now comes from 53 percent wind, 46 percent hydropower and 1 percent landfill gas.
The authors of a new paper in The Proceedings of the National Academy of Sciences say that to get to zero emissions, the country should look beyond wind, solar and hydropower.
Companies like Xcel say they need to find additional ways to cover the costs of maintaining the electric grid. One solution could emerge from a Colorado pilot program.
Health giant Kaiser Permanente is investing heavily in renewables and other green measures, like energy efficiency and waterwise landscapes. Many Colorado-based companies are following suit.
Trump has called global warming a hoax and he criticized wind and solar power as "so expensive." That leaves hope for renewables resting on state policies.
- Those who qualify to be part of the program receive 50 percent of their power from solar.Read more
- The program hopes to train about 350 people in the solar industry.Read more
- The plan would include a sizable fee increase for solar customers of the state's biggest utility.Read more