Amid plans to shed about 750 MW of coal-fired generation, Puget Sound Energy (PSE) is preparing to invest heavily in distributed energy resources (DERs), including non-wires alternatives and possibly microgrids, according to a draft integrated resource plan (IRP).

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“Distributed energy resources, such as battery energy storage and rooftop as well as ground-mounted solar, play an important role in balancing large-scale utility investments and transmission constraints,” PSE said in the draft IRP, which is set to be filed with the Washington Utilities and Transportation Commission on April 1.

Under the draft plan, PSE would add 443 MW of distributed resources by 2025, a nother 820 MW by 2030 and nearly 2,300 MW over 15 years starting in 2031. More than half the additions would be in the form of energy efficiency.

Among the distributed resources outlined are:

While utility scale solar is less expensive than rooftop solar, distributed solar is a key part of the draft plan because of transmission constraints outside PSE’s service territory, the utility said.

“The [non-wires] resources under study have the advantage of being able to address system deficiencies while simultaneously supporting resource needs and can be deployed across both the transmission and distribution systems, providing some flexibility in how system deficiencies are addressed,” PSE said. 

The draft IRP includes a 10-year action plan that details how PSE expects to meet its power supply needs over this decade.

PSE eyes microgrids to boost resiliency

The action plan includes possibly adding microgrids to bolster grid resiliency.

“PSE will also pursue energy security and resiliency investments such as microgrids or infrastructure hardening where specific locations require increased resilience,” the utility said. “These locations could include highly impacted communities, transportation hubs, emergency shelters and areas at risk for isolation during significant weather events or wildfires.”

The draft resource plan didn’t include any specific microgrid plans, but PSE is preparing a solar-based microgrid that includes a 1MW/2MWh battery storage facility.

The Tenino microgrid is being developed with a $2.7 million grant from the Washington Department of Commerce and is expected to be operating in the fall of 2023. The project will provide backup power for a high school.

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