Multi-user microgrid plan for an Oregon suburb includes a bridge, library and industrial district

An ambitious multiuser microgrid plan for Tigard, Oregon – a suburb of Portland – calls for a microgrid concept or series of microgrids to supply power to a bridge, a library and an industrial district, with a main goal of protecting citizens from outage threats associated with wildfires, storms and earthquakes.

But the three-phase plan could also yield benefits other than resilience, according to a study from MBA students at the University of Oregon (UO), “Tigard Microgrid Feasibility Study: A Case for Community Resilience and Renewable Energy.” The authors attend UO’s Lundquist College of Business’ Center for Sustainable Business Practices.

The project could include one larger microgrid or a series of smaller microgrids.

The project’s pluses include a lower carbon footprint, lower energy costs, the potential for Tigard to serve as an Oregon clean energy leader and the possibility of attracting sustainability-conscious businesses to an industrial district that features a microgrid, said the UO study.

Participation from the local utility, Portland General Electric (PGE), is key to ensuring the project is successful, said Gary Pagenstecher, senior project planner and urban designer for the city of Tigard.

“PGE is an essential player in order to do this. They are the grid holder, and this is grid edge development. It won’t happen without tariffs, a metering system and a controller to make it operable,” he said. “When trying something new, all the stakeholders have to be in the room.”

Federal BRIC funds

Tigard is studying the feasibility of the first phase of the project with the help of a $127,000 federal grant through the Building Resilient Infrastructure and Communities (BRIC) program. The study is expected to be completed in the next six months, said Pagenstecher.

The BRIC grant required a portion of the funding to be matched. Energy Trust of Oregon committed $31,000 in matching funds for the work, said Jeni Hall, solar project manager for the nonprofit organization, which helps Oregon residents and businesses transition to renewable energy.

Energy Trust staff is also offering expertise to help make sure any solutions developed will provide the right energy resilience for key community resources, such as fire and police, and to help direct the city of Tigard to any other available incentives when developing the microgrid project, she said. Tigard has provided an $11,000 matching grant for the project.

PGE has also agreed to lend a helping hand. In a November 2020 letter to the city of Tigard, PGE said that to support the BRIC grant it would provide $25,000 as an in-kind contribution of engineering and professional services.

“PGE is interested in the prospect of a community resiliency microgrid and its opportunity to serve joint benefits for the city of Tigard as well as to provide energy and grid services value to PGE,” said the letter.

PGE plans to “diligently, and in good faith, work with the city of Tigard” to plan and develop a resilient microgrid concept that is safe and reliable, the letter said. The goal would be to deliver and test the microgrid concept’s ability to provide services to PGE, including generation capacity, regulation, load following, contingency reserves, frequency response, distribution upgrade deferral and voltage support.

Providing grid value

John Farmer, a spokesman for PGE, said the company is committed to helping Tigard understand how to best integrate the city’s energy storage investment into a microgrid project that also provides utility grid value. That commitment applies to whatever the city prioritizes for investment – whether it’s the first phase of the plan or all three phases.

The first phase of the Tigard project calls for a single-user microgrid at the library that would serve as an emergency operations center during natural disasters, said Pagenstecher.

Solar plus battery storage located on the rooftop and parking lot would be deployed at the library and owned by a single entity – either the city or a private solar developer – according to the UO study. During nonemergencies, the microgrid could help cut utility bills.

A 230-kW photovoltaic (PV) array could be deployed across 16,000 square feet of rooftop space, and an additional 70 kW could be installed in the parking lot.

The solar could potentially meet 60% of the library’s normal load, said Pagenstecher.

Role of the bridge in the microgrid

A second phase of the project would be another microgrid or expanding the library microgrid to other public assets located close to the library, possibly the proposed Red Rock Creek Trail Bridge, a pedestrian and bike bridge. This high visibility project would help educate the public about renewable energy, said Pagenstecher. The proposed solar and storage resources could potentially support the library microgrid and provide other services such as battery charging for Tigard residents and public lighting during outages, according to an earlier feasibility study by PAE Engineers.

The PAE Engineers study looked at both adding only solar to the bridge as well as solar plus storage. The solar component would be about 54,660 kWh.

“The energy resources of the bridge have the potential to serve as one element in a larger approach to community resiliency,” said the PAE study. The bridge resources could be stand-alone resilience assets or part of a larger approach, the study said.

The simplest way to achieve resiliency would be to use an inverter that provides for direct access to electricity generated by PV located on the bridge during daylight hours. Under this scenario, small devices could be charged with real-time generation to support emergency operations, said the PAE study.

A second option would be to include a small battery that could provide electricity at night. It would be sized to store all production from the PV for use during daylight and night hours. The study called for four 32-kW storage units.

“The bridge solar study quantifies the generation capacity as a contributor to a microgrid that could include other nearby PV generators. It could be a stand-alone microgrid with battery storage and a controller,” said Pagenstecher.

Using the microgrid to attract businesses

A third stage of the project would involve expanding the microgrid concept to include the Hunziker Core, a light industrial and manufacturing district located just north of the library. This area has warehouses and large commercial buildings with large parking lots where rooftop and ground-mounted solar could be sited.

This phase is the most complex because of the potential number of generating facilities, owners and users, according to the UO report.

Distributed solar generation and battery storage at this scale would aid in reducing greenhouse gas emissions and cleaning Tigard’s energy mix, support Tigard’s sustainability objectives, create resilient power for local businesses and residents in emergency and nonemergency situations, and potentially reduce costs, said the UO study.

And it could create a clean energy image that would attract businesses to the city.

“The microgrids would bring in new mission-aligned residents and residential developers drawn to a modern, forward thinking and healthy urban area,” said the UO study.

Utility role

Like Pagenstecher, the UO study authors stressed the importance of PGE’s participation in the project.

“The implementation of the district scale MUM [multiuser microgrid] could be facilitated by the city’s enthusiastic endorsement and extensive cooperation from the utility, PGE,” said the UO report.

PGE is now working on a Clean Energy Plan, as required by Oregon law, and it will influence PGE’s integrated planning process, providing a bigger focus on renewable energy and storage, said PGE’s Farmer.

The planning process will consider how PGE can support and integrate community-based renewables and storage, possibly looking at projects similar to the Beaverton (Oregon) Public Safety Center. PGE owns and uses the storage system that’s included in that city’s microgrid.

“That plan will be filed with the Oregon Public Utility Commission in March, and we look forward to continuing to have conversations with our communities about how we can partner to meet our shared decarbonization goals,” said Farmer.

Many stakeholders will reap rewards from the project, the UO report said.

“The district scale application of microgrid technology creates benefits for the grid, the utility, the owner of the generating assets, the city and local businesses, particularly those that value resilient power,” said the UO report.

Interested in learning about more microgrids? Join us May 16-17 in Anaheim, California for Microgrid Knowledge 2023: Lights On!