By last Thursday, the state’s Public Utilities Commission had settled on a new plan for closing or converting some of Colorado’s oldest coal-burning power plants in favor of using natural gas and tapping into renewable-energy sources. But not so fast, says Affordable Reliable Energy Colorado, a group that is challenging the PUC’s scheme for the plants, which currently burn pollution-causing coal. “We have serious concerns about the affordability and viability of their plan,” the group’s executive director, Kelly Weist, tells The Denver Post. AREC, made up of mining interests, industrial energy users, and others, contends the plan is $1 billion more expensive than alternatives, such as retrofitting coal plants with tighter emissions controls. Xcel Energy, which supports the PUC’s decision, disputes the figure.

Meanwhile, AREC is also raising questions about whether all-expenses-paid trips taken by PUC commissioners Ron Binz and Matt Baker were a violation of state law, reports Face the State: Weist claims that Evergreen-based Bentek Energy reimbursed Binz $832 in expenses for a trip to Houston to give a speech during a natural-gas industry event, while Spanish utility Extenda paid $2,845 to fly Baker to Seville, Spain, to speak at a conference for renewable-energy businesses.

On the topic of renewable energy, the state’s clean-energy sector is poised to add another 1,650 new jobs over five years, notes the Post. Such numbers have helped place Colorado in the top five of Clean Edge’s inaugural U.S. Clean Energy Leadership Index.