The Northwest power supply is expected to
remain adequate through 2020, but after that some actions will have to be taken
to keep the power supply adequate.
Due to the retirement of power generating
facilities in 2021 and 2022, the Northwest power supply is expected to be
inadequate to provide the needs of customers unless more capacity is added,
according to an annual study by the Northwest Power and Conservation Council.
John Fazio, senior systems analyst at the
Council, briefing members at its Portland meeting June 13, described the power supply
as adequate through 2020. However, the region will lose 1,330 megawatts of
generation in 2021 when both the Boardman and Centralia coal generating plants
go off line. An additional 479 MW will be lost to the region when the coal
plants Coalstrip 1 and 2 and North Valmy 1, and the gas-fired Pasco plant go
off line in 2022.
“For the regional power supply to be deemed
adequate under the Council’s standard, its Loss of Load Probability must be 5
percent or less,” according to Fazio in a June 5, 2018 Council memorandum (https://www.nwcouncil.org/sites/default/files/2018_0612_9.pdf).
“The Northwest power supply is expected to
remain adequate through 2020,” the memorandum says. “In 2021, however, with the
retirement of 1,330 megawatts of capacity, the LOLP is projected to increase up
to about 6 percent, meaning that the supply would no longer be deemed adequate.
In 2022, with an additional retirement of 479 megawatts, the LOLP increases to
about 7 percent” and it will stay at 7 percent through 2023 “because no major
retirements are planned and the net load growth (after accounting for energy
efficiency savings) is very low.”
The result is that the region’s utilities will
need to acquire about 300 MW of capacity by 2021 and 300 to 400 MW more by 2022
so that the region can maintain an adequate supply (LOLP of 5 percent or less).
Utility integrated resource plans identify
about 800 megawatts of (unspecified) capacity that should be available by 2021.
In addition, the Council has identified about 400 megawatts of demand response
that could be implemented by 2021.
“The Council considers the region’s power
supply adequate if the likelihood of a shortfall is 5 percent or less,” according
to a blog report by the Council’s John Harrison. “A supply shortfall refers to
conditions when utilities are forced to take emergency actions to maintain
service and does not necessarily imply actual curtailment.”
These predictions assume the Northwest
acquires 2,059 average megawatts of energy efficiency by 2023, an assumption
made in the Council’s Seventh Northwest Power Plan.
The report, “Pacific Northwest Power Supply
Adequacy Assessment for 2023,” https://www.nwcouncil.org/reports/pacific-northwest-power-supply-adequacy-assessment-2023,
says that northwest utilities have identified 540 MW of wind generation, about
800 MW of unspecified capacity and other small resources that could be
developed by 2021, but those are not included in the report because they have
yet to be sited or licensed.
There is uncertainty about the future,
however. For example, the assessment is based on medium load growth, but if the
load forecast is reduced by 2 percent, LOLP remains under 5 percent and has
roughly the same effect as adding 650 MW, the report says. On the other hand,
increasing the load forecast by 2 percent drives the LOLP above 10 percent,
almost doubling the amount of capacity needed to remain within the Council’s 5
percent LOLP standard.
The study also assumes a conservative supply
of power from the southwest market, but increasing that supply by 500 MW would
lower the LOLP in 2023 to a little more than 5 percent, so only about 50 MW of
additional capacity would be needed. Lowering the supply from the southwest by
500 MW would drive LOLP to 8.6 percent, requiring an additional 1,050 MW.
Potential shortfall events for the 2023
operating year occur almost exclusively during December, January and February,
the report says.
“Event durations range from a single hour to
over 24 hours and average about 20 hours,” the report continues. “The most
common event duration is 16 hours, which occur over the commonly defined peak
hours of the day. Events also tend to have a uniform hourly magnitude because,
whenever possible, the hydro system is operated in a way to spread out
projected shortfalls evenly across the peak hours of the day. For example, it
is much easier to resolve a flat 100 megawatt shortfall over the 16 peak hours
of the day than a 2-hour 800 megawatt shortfall.”
The Council conducts an annual assessment of
the regional power supply five years into the future as a kind of early warning
of potential electricity supply problems, Harrison said in his blog. For the
assessment, the Council includes only existing generating plants and those that
are sited and licensed. Planned energy efficiency investments are built into