Xcel Energy, Colorado's largest utility, has committed to shutting down two existing coal plants in favor of greener alternatives.
In its 2016 Colorado Energy Proposal, Xcel said that it wanted to replace the plants' output with about 700 MW of solar, 1 GW of wind and 700 MW of natural gas by 2023.
A major drawback of renewable energy sources is that their output is variable. Unlike coal production, the sun does not always shine, and the wind does not always blow.
In the past, adding storage to renewable energy projects added considerable cost and made them cost prohibitive, but that may soon change.
According to a recently released report from Carbon Tracker, Xcel's Colorado goal to get more renewable energy from new projects would be significantly cheaper than getting it from existing coal plants - including storage for energy captured for later use.
The company received nearly six-times as many bids this year as they did in 2013 for developers willing to build the new energy sources, and 134 of the 350 bids for solar energy. The previously cheapest known price for solar and storage was $45/MWh, and some of the most recent bids Xcel received beat that cost by nearly $9.
Nationally, coal burn has decreased 2% year-over-year as utilities transition to cheaper gas and renewables. The falling price of storage shows just how uncompetitive coal really is.
Xcel serves nearly 3.3 million electric customers in the upper Midwest, Colorado and New Mexico.