Bus Barn Microgrid Demonstration Project

Climate Commitments Create Challenges for Utilities and Customers

Washington aims to reduce carbon emissions at least 25% below 1990 levels by 2035. Along the way, there are many practical lessons utilities must learn in order to enable a faster transition to clean electricity. Massive shifts in transportation, building infrastructure, and intermittent renewable generation dramatically reshape power system planning at transmission scale. As this occurs, distribution networks must also increasingly accommodate customer-sited generation and loads that enable net-zero transportation and buildings. Both present challenges to traditional utility interconnection processes and reliability.

CEL Partners with Stakeholders to Demonstrate Improved Resilience and Decarbonization

CEL has partnered with Franklin Pierce School District (FPSD) and Tacoma Power to turn disruption into opportunity. The joint Bus Barn Microgrid Demonstration Project will demonstrate how one school district’s fleet electrification, solar generation, and resiliency needs—when combined with modern energy management technologies, community engagement, and utility operational innovations—exemplify how local schools and districts can more seamlessly integrate Distributed Energy Resources (DER) and improve local resilience while decarbonizing transportation, buildings, and the grid.

Bus Barn Microgrid Fosters Shift From Disruption to Resilience

FPSD has purchased several electric school buses. Over the next 15 years, they intend to electrify their entire fleet of 60+ buses and vehicles. In addition, the district plans to install 100 kW of solar on the high school’s roof. Without innovative controls and operations, these seemingly positive developments present a conflict between normal utility distribution system operation for reliability and the imperative to decarbonize. In typical configurations, building and transportation electrification and back-feed from DER like solar PV strain utility distribution infrastructure. Full fleet electrification at FPSD would create an unmanaged charging peak of 1.3MW. FPSD is electrically heated with a winter peak load of ~1.1MW. The resulting combined 2.4MW load peak would overwhelm the school’s meter. This would cause power factor issues and require frequent reconfiguration of the local distribution system.

The Bus Barn Microgrid Demonstration Project is demonstrating an innovative, community-centric microgrid design and interconnection process. The project will satisfy customer goals for less carbon-intensive operations while managing loads to correspond with utility distribution capacity and broader renewable energy integration goals. The microgrid will manage charging and other peak loads, reducing peak load to 1.5MW. This will fundamentally change the way the building operates and give building operators access to benefits such as added resiliency.

CEL’s innovative partnership with community, customers, and the utility supports resiliency by:

  • reducing the chance of short-term supply disruptions on utility distribution circuits
  • improving the economics of renewable energy by improving end-use load shapes to better align with renewable generation

Our efforts build on work from Pacific Northwest National Labs that estimates school bus loads and examines the ability of additional on-site storage to reduce the district’s charging peak.

Bus Barn Benefits

The Bus Barn Microgrid Demonstration Project has many benefits for the school, utility, and Washingtonians:

  1. Improves Tacoma Power's ability to quickly interconnect customer-sited microgrids, transportation electrification, and generation projects. This is because the project fosters a better understanding of the role that innovative control and operations play in shaping local distribution capacity.
  2. Demonstrates methods to reduce demand spikes, smooth loads, and better integrate renewables through autonomous management of behind-the-meter load shape to ramp, shed, or shift.
  3. Explores novel business use cases that enable customers to benefit from clean, on-site backup and resiliency in exchange for utility operation or optimization of assets.
  4. Allows regional STEM and CTE professionals to access project data about innovative technologies and develop energy flexibility curricula. These can then be used in developing a school-to-career pipeline for economy-wide decarbonization jobs.
  5. Explores incentive options for the integration of bus batteries into the grid that will increase the speed of school bus electrification at Tacoma Power and around the state. The addition of four electric buses at FPSD is the equivalent of removing 20 cars from the road. It will eliminate close to 100 tons of greenhouse gas emissions.
  6. Creates a playbook for the 295 school districts and host utilities in Washington to follow when electrifying school building loads and bus fleets.

Bus Barn Microgrid Project Team Engages the Community

One of the project team’s deliverables is to hold regular meetings to gather community input and increase their understanding of school energy usage and the benefits of microgrids. Our process educated community members about the energy resources schools provide and gave them deeper insight into what it takes to support these resources. Equipped with this understanding, community members engaged in thoughtful and productive discussions surrounding resources and resiliency.

CEL leveraged match funding and in-kind support from Tacoma Power to host a six-hour Smart and Resilient Schools (SRS) Energy summit. The SRS Summit comprised interactive educational activities. Attendees included students, teachers, and building maintenance professionals from elementary and secondary school districts, as well as nontechnical community members. We wanted to see how stakeholder preferences interact with smart building control of space conditioning, EV charging, electric buses, and on-site solar and battery systems. We learned a lot from these discussions (see below) that will inform our ongoing work.

Key Takeaways from Bus Barn Project

  • RELIABILITY: Parents are heavily impacted by outages when kids are sent home from school early. Building operators' primary responsibilities are serving occupants followed by keeping costs low and following district policies. This is difficult to do with aging equipment.
  • KNOWLEDGE: Even the best informed have less insight than they expected into the complexities and nuance of the services provided and the energy sources that they come from.
  • CONTROLS & SYSTEMS: Customers took great interest in the load shifting from HVAC and other building systems to address emergencies.
  • RESPONSIBILITY: Building operators are unclear on the county's expectations of schools' responsibility in the context of a wider disaster.
  • EDUCATION: Customers were interested in replicating this learning to others and exploring longer-duration outages and other scenarios.
  • RESILIENCY: Building systems need to be more resilient and control systems need to be easy to use and seamless to customers.
  • GENERATION: There are energy generation alternatives that have different carbon costs and advantages. Solar is not the only good solution.
  • AIR SYSTEMS: Customers want to learn more about the difference between DOAS and HVAC and the advantages of the two.
  • MICROGRID: Customers would enjoy going through and understanding the integration process for all the different systems discussed.
  • USAGE: Schools use energy over a wider period of time than just when students and staff are in the building.
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