Planning reserve margins in California and Texas will be "tight" this summer, and New England generators could face uncertain supplies of liquefied natural gas (LNG), the North American Electric Reliability Corporation’s (NERC’s) newly released 2012 Summer Reliability Assessment finds.

The 195-page assessment forecasts that between June 1 and Sept. 30, a majority of NERC’s assessment areas will have sufficient resources to meet summer peak demands. However, the Electric Reliability Council of Texas (ERCOT), the grid operator that serves about 85% of Texas, shows planning reserve margins of 13.5%, below NERC’s reference margin level of 13.75%. And in California, planning reserve margins of 15.2% are barely above NERC reference margin levels by 0.1% for the summer.

"Insufficient reserves during peak hours could lead to an increased risk of entering emergency operating conditions, including the possibility of curtailment of interruptible loads and even rotating outages of firm loads," said the international regulatory authority established to evaluate the reliability of the North America bulk power system.

California’s capacity resources took a hit when the San Onofre Nuclear Generating Station (SONGS) Units 2 and 3—a total of 2,150 MW—was indefinitely taken offline earlier this year due to premature wear in the units’ steam tubes. "The unavailability of this plant and a continuation of drought conditions accompanied with a stretch of higher‐than‐average temperatures or significant generation or transmission outages, could result in the deployment of load-shedding procedures in the San Diego and Los Angeles Basins to maintain the reliability of the bulk power system," NERC said.

Both ERCOT and the California Independent System Operator (CAISO) have instituted procedures to bring mothballed units back into service—ERCOT, about 2,000 GW, and CAISO, 452 MW—and have begun accelerating the completion of transmission projects. But "in California, with 14,000 MW of expected import transfers from neighboring areas, increased reliance on transmission ties to import the required power could further stress the system," NERC cautioned. The organization pointed to the Sept. 8, 2011, event that blacked out a large swath of Southern California, parts of Arizona, and Northern Baja Mexico, and which official documents have concluded stemmed from “weaknesses” in operations planning and real-time situational awareness.

Capacity resources in North America have increased by about 12,310 MW since 2011, NERC said, but most additions were centered in PJM Interconnection’s region, the SERC Reliability Corporation (SERC) region (which comprises 16 central and southeastern states), and New England. PJM showed the largest absolute growth, of about 5,018 MW, but much of the increase was tagged to the recent integration of Duke Energy Ohio/Kentucky (from MISO).

Variable generation—and specifically wind power—also significantly increased, particularly in MISO and New England. A total of 4,567 MW of nameplate wind generation has been installed since last year, reflecting a modest increase of 1,880 MW of expected capacity on-peak.

Meanwhile, total internal demand is projected to drop by 3,700 MW, about 0.4% less than last year. ERCOT and New York show the largest percentage growth, with each area forecasting about 1.7% of increased peak demand. North Dakota, South Dakota, and Minnesota show the largest relative decrease compared to 2011, of about 5.7%.

As in 2011 projections, this summer, gas-fired generation (38%) will continue to be the dominant on-peak fuel source during periods of peak demand, followed by coal (29%) and nuclear (10%) generation to cover base load.

Though fuel supply or delivery issues are not foreseen for the summer, foreign supply-chain "issues" could reduce the amount of LNG shipped to New England this summer, which could impact LNG-dependent generation in northeastern Massachusetts and the Greater Boston area. ISO-NE is developing procedures to ensure plants operated during peak periods, NERC said.

While uncertainties prevail about unit retirements, Section 316(b), and retrofit and maintenance schedules related to new environmental regulations, "no impact is expected from any pending and/or final environmental rules" this summer, NERC concluded.

"While some generator retirements have already been announced, all retirements have been accounted for and included in this assessment. Additionally, there is little uncertainty that generators would retire or derate between the time of this publication and the summer peak." NERC said it would examine the impact new rules could have in its forthcoming long-term assessment.

Sources: POWERnews, NERC