When defining the existing system resource supply, there are many characteristics and parameters we can use. The installed nameplate capacity of the system describes the manufacturer rated output of the generator. While a useful parameter, generators rarely run at full output at all times. Rather, by defining the average resource capability, we are describing the typical expected output that the generator could produce. This takes into account realistic discounts such as an estimated annual capacity factor for variable energy resources, forced outage rates for fossil fueled resources, and scheduled maintenance for nuclear resources (among other examples).

Existing System Installed Nameplate Capacity vs. Capability

In reality, resources dispatch according to a variety of real-time factors: load, hydro and weather conditions, fuel prices, wholesale electricity prices, and maintaining system adequacy, reliability, and reserves. A good example of this is the difference in historical dispatch between 2018 and 2019. Hydro conditions were above average in 2018 and fossil fuel resources were dispatched less (16% of regional total production). In contrast, 2019 was a very poor hydro year, and the region relied more on its fossil fuel resources (24%). Nuclear was consistent, as were renewable resources.

Existing System Annual Energy Production: 2018 vs. 2019

In addition to describing the generating capabilities of the existing system, we must also understand what constitutes the region, as defined by the Northwest Power Act . When accounting for regional resources, we must consider that some resources physically located within the geographic boundary of the region may actually be contracted to serve load outside of the region, and vice versa - resources exist outside of the region but are owned by- or contracted to- utilities and customers in the region. A good example of this is the region’s wind fleet. About 1/3 of the installed nameplate capacity of wind physically located in the region serves load outside of the region, namely California.

The actual contribution of each resource depends on its dispatch, which can vary from year to year (see historical generation).

For an up-to-date, detailed project-level information on the resources that make up the PNW, see the Council’s generating resource project database and accompanying interactive map. To understand how the region’s generating resource projects were frozen and reflected in the development of the 2021 Power Plan, see “Translating the Existing System to the Council’s Models.”