Pitkin County, Holy Cross Energy and the Roaring Fork Transportation Authority are studying the feasibility of developing a microgrid to connect a cluster of public facilities near Aspen/Pitkin County Airport so that they could be powered by renewable energy, autonomous from the larger electric grid and protected from outages if service to the rest of the area goes down.
A $200,000 grant from the state of Colorado Department of Local Affairs (DOLA) is supporting the feasibility study. The grant, awarded to the state in the fall of 2019, was initially supposed to have been spent by the end of 2020, but the COVID-19 pandemic has pushed the deadline to the end of 2021, according to Pitkin County officials.
Work is underway to study baseline existing conditions and technological concepts in service of establishing a microgrid connecting the airport, the county’s public-works facility and RFTA’s bus barn, all of which are near one another straddling Highway 82 about 3.5 miles from Aspen’s core. Holy Cross infrastructure and the utility’s Aspen office, which is in the neighborhood, are also part of the study. Once the feasibility study is complete, officials will seek additional grant funding from DOLA — as well as from the Federal Emergency Management Agency — for implementation.
Microgrids are self-contained systems that allow users to operate as an island disconnected from the larger grid. Each system is unique, but they tend to rely on on-site power generation, energy-storage capability and efficiency. The county-RFTA-Holy Cross concept also seeks to capture the excess heat generated by operations at the facilities, harnessing and sharing it with other buildings.
The idea was influenced by the summer of 2018 Lake Christine Fire that burned nearly 12,600 acres near Basalt and threatened the main electricity transmission lines serving the upper valley. At the same time, the county’s plans to build a new airport terminal and airfield were moving forward with energy efficiency and on-site renewable-energy generation in mind.
Last week’s natural-gas outage, cutting off heat to 3,500 homes and businesses in Aspen, served as another reminder for how a lack of resiliency can leave a community exposed to disruptions in basic services. The saving grace for many who went three nights without heat powered by natural gas was the distribution of thousands of electric space heaters.
The sites being studied around the airport lend themselves to the microgrid concept thanks to their proximity and the vital public functions they serve: landing planes, keeping the buses running and maintaining snowplows. Holy Cross transfer stations in the vicinity are also well sited and are needed for a microgrid to safely function.
Microgrids are becoming increasingly common. Pittsburgh International Airport is establishing one powered by solar and natural gas harvested from shale underneath the facility and burned by on-site generators. The solar-powered microgrid operated by the Blue Lake Rancheria tribe in Humboldt County, Calif., kept electricity flowing at a hotel and gas station to support life-saving services when wildfires forced the rest of the grid to go down in the fall of 2019. The county-RFTA-Holy Cross project, however, is unique.
“This is kind of breaking ground to be linking this many public facilities that provide such crucial services,” said Zachary Hendrix, the long-range planning and climate-action plan administrator in the county’s community development department.
Work to date has involved studying existing conditions at each facility that would be connected and examining where efficiency gains can be made.
“We call it an energy box, so if you put all the facilities inside an imaginary box, it’s the energy that would come from that,” Hendrix said.
RFTA has been going down that road at its bus barn for many years, and the facility, which now includes infrastructure to charge eight electric buses, utilizes a ground-source heat pump and other energy-saving technology.
The county’s public works building includes a 105-kilowatt solar-power array but could benefit from upgrades to its lighting system, Hendrix said.
Among the largest energy consumers in the area is the snowmelt system at the pedestrian underpass connecting the airport to the Aspen Airport Business Center (AABC) under Highway 82.
Each site is being studied for how it can update its systems to save more energy.
“The work so far has identified significant energy conservation potential at the existing sites studied,” Holy Cross CEO Bryan Hannegan wrote in an email.
The second phase of the feasibility study will investigate what technology would be needed and where among the sites is best suited for the component parts. Developing more solar capacity and deciding on the location of shipping-container-sized lithium ion batteries to bank the energy will be key.
The heat-transfer concept is rare in North America but more common in Europe. The idea is to capture the excess heat generated by buses warming inside RFTA’s bus barn and in the boiler rooms at the facilities. This would require new infrastructure, such as underground piping connecting the facilities, and Highway 82 could be an impediment to that system, officials acknowledge.
While existing infrastructure will help support electricity sharing among the sites, the partners will lean on Holy Cross to explore the engineering details in Phase 2 of the feasibility study, Hendrix said.
County officials hope to wrap up the feasibility study in June. It’s unclear when funds would be available for an implementation grant, but the parties want to be ready.
RFTA assistant planner Jason White, who has been working on the feasibility study, said the agencies would be “well positioned” for a future implementation grant because they have already shown a “high level of integration” and DOLA appreciates seeing local entities working together.
Even if a fully independent microgrid for the sites takes longer to come together, other benefits can be more immediate, White said. Gains can be made in real-time operational sustainability and learning how the buildings can work together to share and use energy more efficiently.
Scalability and replicability are among the grant criteria, Hendrix said. Part of the “joy of the microgrid,” he said, is that once the core is in place, it’s designed to be expanded. With a Colorado Mountain College campus, an Aspen Fire Protection District station and hundreds of residents between the AABC and North 40 neighborhoods nearby, the hope is that everyone could benefit. The partners also hope the project can help inform efforts to connect other facilities throughout the community to microgrids.
“How do we set up subsets so that we are not all reliant on a main trunk line?” said Cindy Houben, the county’s community development director, referring to how utilities are delivered.
It’s all part and parcel of a larger sustainability and resiliency push, which includes land-use code revisions that require new buildings in Pitkin County to be wired to accommodate on-site solar. In addition, any building with more than 10 kilowatts of solar now must have on-site storage. A significant number of these smaller-scale batteries have come online throughout the county, Hendrix said. Other recent regulatory changes have tightened the pace of growth allowed in the county and require new buildings to be more energy efficient.
“We are doing the on-the-ground, ready-set-go work for renewables, and Holy Cross is looking at how do we structure it from the energy-transport lines so that we can not only have the resiliency of backup, but also looking at the overall system,” Houben said.
There is no one lever to pull or silver bullet to address climate change and its impacts, Hendrix said, but the combined effort across multiple sectors can make a difference.
“Hopefully when we pull on all these levers together, we can create a substantial impact on our climate change and greenhouse-gas emissions,” he said.