Rethinking 'big grid'
Increasingly, microgrids seen as way to combat climate, geographic vulnerabilities

Aspen and tiny Springfield, in the southeast corner of the state, have almost nothing in common other than being county seats in Colorado. But, they also happen to be in electrical cul-de-sacs, the tricky spot at the end of transmission lines.

Both places have gone dark in the past when transmission has been disrupted. Microgrids may help in their electric isolation. 

Aspen, of course, has a backdrop that inspires photographers and has several dozen billionaires among its residents. It also has daily plane service for those who can’t afford their own jets. Thinkers from around the globe gather to puzzle through the world’s problems. It’s a small town unlike nearly all others on the planet.

Springfield is a more humble place, its scenery esoteric, its economy more sketchy, with the most productive farms dependent on the declining Ogallala and other aquifers. Oklahoma lies a half-hour south, Kansas just a bit farther east. There’s just one real restaurant, and it goes dark after 2 p.m. on Sunday, remaining so until Tuesday morning.

A new round of state grants is helping Springfield and other rural towns around the state, including Silverton and Ridgway, plan microgrids. Aspen, on the other hand, is creating its own without state aid.

Aspen came close to going dark on the Fourth of July weekend in 2018. The Lake Christine wildfire had started burning a transmission pole that delivers electricity from the lower Roaring Fork Valley. Had firefighters arrived a little later, Aspen might have been unelectrified on one of its busiest weekends.

Aspen’s microgrid, nearing completion, will not keep Aspen fully electrified if something similar happens, but a few core functions will continue to get power.

The site is located along Highway 82 near the Aspen-Pitkin County Airport, adjacent to the Pitkin County public works headquarters and a bus barn for Roaring Fork Transit. Foundations have been poured, and two batteries the size of shipping containers will be installed this autumn, but the system won’t be operational until mid-2025.

Gerald Fielding, a Pitkin County engineer, describes this microgrid as a little island. It will have maximum electricity consumption at the airport and its two other facilities for two hours – longer yet, if some demands can be shaved. None of this includes charging of electric buses.

The airport already has backup electricity via a natural gas generator, as required by the Federal Aviation Administration. These batteries will provide a secondary and non-fossil fuel backup.

Batteries aren’t just for emergencies, though. The microgrid will be managed by Holy Cross Energy, whose service territory includes about half of Aspen and the rest of the Roaring Fork Valley. The batteries will need to be drained twice a month, and Holy Cross will incorporate that into its operations.

If transmission to the upper Roaring Fork Valley were disrupted, this microgrid would help only a little. The batteries have capacity to satisfy just 2.9% of the total peak winter demand for the Aspen area. That includes downtown Aspen, which is served by the municipal electricity provider.

Providing complete backup in the upper Roaring Fork would require far more investment. This small island, so far, costs $3.35 million. To quadruple the batteries and directly tie into a 5-megawatt solar project a few miles away would escalate the cost to $25 million.

Ben Luck, a Holy Cross engineer, says because of the expense, other microgrids in the Holy Cross service territory will likely be community-driven.

“By definition, a microgrid is a large investment that benefits one small part of our system,” he explains. “This project was driven by Pitkin County. We will play a supporting role, but the driving force will have to come from the community to which it will deliver benefits.”

Microgrids have been defined in various ways. Colorado legislators use a definition with a broad scope. It could include individual buildings, universities or other campuses, or even entire communities. Or something in between.

Other definitions use the analogy of an island. In normal times, the island has connections to the mainland, i.e. the broader electrical grid. It can, however, function solo.

 “A microgrid can connect and disconnect from the grid to enable it to operate in both grid-connected or island mode,” according to the U.S. Department of Energy definition.

A backup strategy

Microgrids are not particularly new. Hospitals and other critical infrastructure have long had backup generators that typically burn diesel or other fuels. Today’s microgrids hew to this same idea of providing backup power but, aided by batteries, can create larger islands.

Interest has been spurred by an uptick in violent weather. Boulder resident Peter Lilienthal, former chief executive at HOMER Energy, a company specializing in microgrids and other electrical innovations, points to Hurricane Sandy in 2012 as a pivotal event.

Lilienthal, speaking on a recent webinar sponsored by Boulder’s Empower Our Future, explained that the multi-day power outages provoked by the hurricane illustrated the need for alternatives when the electric grid goes down.

 “You are realizing that it’s not just hospitals that need backup generation,” he said. “Grocery stores and gas stations become critical infrastructure.”

This summer’s Hurricane Beryl seemed to prove the point in Houston. Microgrid Knowledge, an industry website, reported that grocery stores and homes with microgrids weathered outages for more than a week.

 “It is past time to start recognizing that the 20th century ‘Big Grid’ model doesn’t work well as weather gets increasingly extreme in the 21st century,” Boulder’s Glustrom said.

Interrelated with the rise of microgrids is the growing role of electricity in our lives. If we’re going to ask the grid to deliver power not just for our lights and dishwashers but also to heat our homes and power our cars, we need some backup strategies, right?

Creating resiliency

Microgrids aren’t just suitable for small or rural applications – they can be created in densely settled urban areas as well. Xcel Energy, for example, is wrapping up completion of six microgrids that resulted from 2018 state legislation. Those microgrids seek only to provide backup power for individual buildings.

They have been completed at the Alamosa Recreation Center, the Arvada Center and Nederland Community Center. One is also planned at the Denver Rescue Mission.

Xcel explains that the sites were selected after communities were encouraged to submit projects that would support facilities deemed critical. The Arvada Center – a concert and arts venue –was chosen because it is a recovery and shelter hub in the city’s disaster plan.

There is also a microgrid at Denver International Airport, where a battery system will power the tram that moves between the terminal and concourses.

However, rural areas exhibit greater need. For example, Red Feather Lakes, an unincorporated hamlet northwest of Fort Collins, has had a small microgrid since 2018 to power crucial services if the electric grid gets disrupted, as nearly happened during wildfires in 2020. It won’t provide power for outlying cabins but does provide power for the volunteer fire department, the community building, post office, area businesses and other buildings.

In addition, San Miguel Power Association is exploring community-scale microgrids to boost resiliency for Rico, Ophir, Ridgway and Silverton, where blizzards and avalanches have threatened reliability. The town of Telluride already has a microgrid for its sheriff’s office and a school.

Colorado legislators had rural areas primarily in mind in 2022 when they passed HB22-1013. It says microgrids can “help increase a community’s resilience regarding severe weather or natural disasters … by providing an alternative, reliable source of electricity.”

Electrical cooperatives are getting the bulk of grants, abetted by $10.3 million in federal money. The law also allocated $3.5 million for microgrid planning and implementation. Known as the Microgrids for Community Resilience Program, it recently announced $2 million in grants, including much of the $40,000 that Springfield and its wholesale supplier, Arkansas River Power Authority, will use to explore backup power and microgrid opportunities. 

Other grants went to microgrid projects in or near Ridgway, Estes Park and Livermore, east of Red Feather Lakes, and Longmont-Brighton. Previous grants have been given for microgrids in Bergen Park, in the foothills southwest of Denver; Montrose County and Delta; and one in the Beulah-Gardner area, of the southern Front Range.

The Colorado Microgrid Roadmap emphasizes rising extreme weather events. It cites the National Centers for Environmental Information in reporting that Colorado had 70 confirmed weather/climate events since 1980 with economic losses exceeding $1 billion. Transmission lines can be vulnerable to extreme heat, cold and wildfire, and renewable energy can be weather-dependent.

The roadmap also points to social vulnerabilities, places where populations are particularly susceptible to the impacts of outages. Five regions with the highest vulnerabilities are identified in the roadmap. The regions cover parts of 19 of Colorado’s 64 counties and have 10% of the state’s population:

•  Pueblo, Las Animas, Bent and Otero;

• Alamosa, Conejos, Costilla, Rio Grande and Saguache;

• Archuleta, Dolores, La Plata, Montezuma and San Miguel;

• Mesa, Moffat and Rio Blanco; and

• Lake and Grand.

This was extracted from BigPivots.com, an e-magazine about Colorado’s energy and water transitions. Subscriptions are free.