by Allen Best
Another small but important piece of the giant puzzle that Holy Cross Energy has set out to solve was revealed Tuesday.
The electrical cooperative serving members in the Vail-Aspen-Rifle area has agreed to purchase electricity from a solar and battery storage project being built by Ameresco Inc. Near Glenwood Springs, on the Spring Valley Campus of Colorado Mountain College, the company will install solar panels capable of generating a maximum of 4.5 megawatts of electricity.
Adjacent to the solar panels it will operate battery storage with a capacity of 5 megawatts (or 15 megawatt hours). Batteries will be charged with electricity generated by the solar panels.
The batteries can be tapped to supply electricity during times of peak demand on a daily basis. In the Vail-Aspen area, peak demand typically occurs in evening hours, with the strongest demand during winter months.
The lithium-iron-phosphate batteries can also augment Holy Cross’s electrical generation during times of disruption, such as caused by wildfires or storms.
“That battery and local generation is an important part of the infrastructure that is real important to creating a resilient energy system for the future,” said Steve Buening, the vice president for power supply and programs at Holy Cross.
The battery storage will be able to have 5 megawatts of power vs. 15 megawatt-hour of capacity. Beuning compares the 5 megawatts to what happens when you press on the gas pedal of an internal-combustion car, while the mega-watt hour is how much the gas tank can hold.
With 45,000 members, Holy Cross is among the larger of Colorado’s 22 electrical cooperatives. As of 2018 it was responsible for 2.2% of electrical sales in the state.
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Holy Cross has been assembling disparate pieces of infrastructure, some in and among the communities it services, others hundreds of miles away, as it pursues a goal of completely decarbonizing its electrical supply by 2030.
In addition to the new solar-plus-storage complex near Glenwood Springs, Holy Cross plans a 5-megawatt solar farm on McCain Flats, near the Aspen/Pitkin County Airport. Construction is scheduled to begin this spring.
Complementing this local generation will be electricity generated for Holy Cross at the Arriba wind farm, to be constructed during the next year along Interstate 70 near the eponymously named town 120 miles southeast of Denver. The wind farm will have 100 megawatts of capacity, enough to supply roughly a third of demand by Holy Cross members.
In storage, Holy Cross has something of the same approach, a mixture of local and smaller and elsewhere and larger.
See also Dec. 15, 2020 story: Holy Cross and the ‘Journey to 100%’
Directors of Holy Cross in 2020 adopted a plan that lays out potential strategies, including pumped-storage hydro. Water in pumped-storage projects is released to generate electricity to meet peak demands, then pumped uphill again when electricity is more abundant and hence cheaper.
It’s not new technology. Colorado has two such projects, the larger and older being near Georgetown. There, the Cabin Creek project uses a 1,200 feet vertical drop between two reservoirs to generate a maximum of 324 megawatts. The system went on-line in 1967 but has been upgraded since then.
Bryan Hannegan, the chief executive of Holy Cross, has spoken about the value of small pumped-storage hydro projects in the Aspen-Vail area, perhaps combined with larger capacity pumped-storage projects elsewhere.
Why the battery storage now for Holy Cross instead of waiting for prices to tumble further. Prices of battery storage have dropped about 80% in the last decade and are projected to decline even more, from $137 per kilowatt-hour to as low as $100 by 2023, according to Bloomberg New Energy Finance.
Holy Cross decided that the prices were already good enough.
“One thing that may be holding back investment in utility-scale energy storage is concerns about being an early adopter at higher prices than in the future if battery prices continue their downward trend,” says Buening.
That being noted, the savings are good enough already to yield lower costs of electricity for Holy Cross members.
“We were ready to go ahead,” he says.
Xcel is also planning 275 megawatts of battery storage as it closes two coal-fired power units at Pueblo in the next several years. In a recent filing with the Colorado Public Utilities Commission, the utility plans even more in the years beyond 2024. It’s Colorado’s largest utility with 52.5% of Colorado’s electrical sales for 2018.
Photo at top is rendering of the solar-plus-storage project at the Spring Valley Campus near Glenwood Springs.
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