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Snohomish PUD IRP Focuses On Conservation And Energy Storage

Snohomish County Public Utility District’s (PUD) recently adopted 2021 Integrated Resource Plan (IRP) focuses on conservation and energy storage to meet electrical demand through 2045.

The “unusual” 24-year long planning horizon of the IRP is designed to enable Snohomish PUD to study how it will transition to 100 percent clean energy by 2045 as called for by Washington State’s Clean Energy Transformation Act (CETA), the public power utility said.

Over the long term, Snohomish PUD expects its conservation efforts will allow it to maintain a surplus average annual energy position until 2043. However, seasonal capacity needs will persist, both during the utility’s historic winter peak period and during a growing summer peak that is being driven by higher demand for air conditioning.

Over time, the PUD sees the impact of climate change transforming weather patterns in the Pacific Northwest, with winter load gradually declining as a result of increased hydro production from November through February and summer needs increasing with warmer temperatures while spring and summer hydro production levels decline because of reduced snowpack.

The acquisition of new conservation resources will reduce the scale of capacity needs and defer the utility’s need for long-term capacity resources until the mid-2020s. At that point, new capacity resources would also meet the PUD’s seasonal and peak loads and limit exposure to price volatility, the IRP found.

In past IRPs, Snohomish PUD did not identify specific long-term capacity needs, but the 2021 IRP proposes that the utility’s capacity needs be addressed with long-duration energy storage augmented by cost-effective demand-side load shifting programs such as demand response and new “smart rate” programs.

Advanced metering infrastructure (AMI) technology – such as the PUD’s Connect Up program currently under development – will be a critical component in the implementation of demand-response load shifting programs, the IRP said.

However, the renewable resources predominantly available in the Northwest today, such as wind and solar energy, “do not possess the operating characteristics necessary to meet the PUD’s on-peak capacity need in a reliable and cost competitive manner at this time,” the IRP found.

Over a 10-year planning horizon, the IRP identified a need for 70 megawatts (MW) of energy storage and only 5 MW of solar power capacity.

Over that same period, the IPR projects the need for 76.6 MW of conservation and 31.6 MW of demand response resources.