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Xcel’s coal-retiring Colorado plan ‘approved’ with 125MW extra battery storage

As well as solar and wind, the plan calls for battery storage and existing gas generators to improve flexibility and reliability of the electric system. Image: Xcel Energy.

Utility Xcel Energy’s latest resource plan for Colorado, aimed at increasing renewable energy generation and aiding the retirement of coal plants, was approved by the state’s Public Utilities’ Commission (PUC) on Monday.

The local Denver Post reported that the PUC had approved the plan on Monday, 2-1. Building on the utility’s 2016 Electric Resource Plan - 120-Day Report, the latest version was first put forward in June. Energy-Storage.news reported at the time that in addition to accelerating the retirements of the Comanche 1 and Comanche 2 coal generation facilities, Xcel claimed the plan could save customers around US$215 million, attract US$2.5 billion investment across eight counties of the state and get Colorado to close to 55% renewables by the year 2026.

“This 120-Day Report presents an opportunity for the Commission to continue the transformation of the Public Service generation portfolio in a manner that simultaneously achieves economic and environmental benefits,” Xcel Energy wrote in the document.

Some other highlights of the plan include a commitment to increasing the “operational flexibility” and reliability of the electric system by pairing generation with battery energy storage and flexible natural gas generation.  

The plan therefore would add 1,100MW of wind, 700MW of solar and crucially, 275MW of energy storage which Xcel stipulated would be “all embedded in solar-plus-storage projects”, as well as relying on 380MW of existing flexible gas generation. Xcel would own around 50% of the new renewable generation capacity and the 380MW of gas, the latter of which would amount to about 58% of the utility’s dispatchable and semi-dispatchable resources.

Incidentally in January of this year, Xcel received a series of what it called “incredible” low prices from companies bidding to execute projects in its service areas, including wind with battery storage at US$21 per MWh, solar-plus-storage for US$36 per MWh and solar-wind-plus-storage at US$30.60 per MWh.

Local radio station Colorado Public News did however report some remarks by PUC member Bob Bergman, who apparently stated that the US$215 million of possible savings quoted by Xcel might be overplayed, and that customers may not feel the economic benefit until the mid-2030s.

The Denver Post reported that the commission is likely to issue a written approval of the plan in the first week of September. Meanwhile, Erin Overturf, a PUC-specialist lawyer who works with environment and resource protection group Western Resource Advocates reported that the PUC on Monday approved a “preferred” version of the Clean Energy Plan, as opposed to an “alternative”. According to Overturf, the difference is that the approved version includes one extra 250MW solar PV project paired with 125MW of battery energy storage in Colorado’s Pueblo County.     

Energy storage company Younicos tweeted that it was a: "Truly noteworthy decision by the #Colorado PUC - #renewables and #EnergyStorage replacing #fossilfuel here (and elsewhere) at a record pace. It's cleaner, safer, and the economics work!"

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