More than 330 GW of utility-scale wind and solar generation capacity is expected to come online across North America through 2029, but plans for new transmission have hit a slump and are not keeping pace with that expected influx, the North American Electric Reliability Corp. warned Dec. 19.
In a press briefing on NERC's 2019 long-term reliability assessment, John Moura, NERC's director of reliability assessment and performance analysis, also reiterated the organization's long-held reliability concerns regarding some regions' increased reliance on gas-fired generation and challenges around reliably integrating renewables and distributed generation into the bulk power grid.
As for transmission planning, less than 15,000 circuit miles of new power lines are expected over the next six years, which is "considerably less than the nearly 40,000 circuit miles planned earlier this decade," the report said. At least two regions, the Southwest Power Pool and Electric Reliability Council Of Texas Inc., are already seeing their existing and planned power lines reach full subscription levels, NERC said. Yet, new solar and wind projects equivalent to about 30% of the NERC region's current total generation capacity are expected to come online by 2029, Moura noted.
Moura reported that grid operators and planners are following all reliability standards. "That is, transmission is being built (and) any reliability reasons or any deficits in meeting (reliability) criteria are being addressed," he explained. "However, what we don't see are large transmission projects, long transmission projects that are really going to be needed when we think about the resource base that's coming in — the amount of wind that's coming in," particularly in the more remote locations where the wind and solar are likely to be built.
Moura also noted that bulk power system owners and operators often address reliability concerns that NERC flags by the time the problem is expected to arise, which he said is likely to prove true for two regions that could see dwindling reserve margins in the projected future.
Specifically, ERCOT and the NERC reliability region for Ontario are projected to have less than the reference margin levels for reserves for the next five years. Moura noted that additional generation resources are expected to come online to address ERCOT's challenge, and Ontario is working on contracting for the incremental capacity to make up for a generation supply decrease largely related to nuclear plant refueling-related outages.
A changing resource mix
When it comes to new wind and solar, the Midcontinent ISO, PJM Interconnection, SPP and ERCOT have the most total planned capacity. In addition to more utility-scale wind and solar, 8 GW of bulk power system-connected electric storage and 35 GW of distributed generation rooftop solar are expected in North America by 2024, NERC reported.
The report noted that additional "flexible resources" will be needed to accommodate such large amounts of wind and solar generation additions, including the solutions to inverter-based resource connections that are being implemented. Another challenge is that utilities and grid operators may lack the ability to monitor, or control, the operation of distributed resources. Operators need more information and data system planning, forecasting and modeling as the amount of these resources increase, NERC said.
Concerns associated with ramping are now largely confined to California, which is where the California ISO manages much of the grid, the report noted. "However, as solar generation increases in California and various parts of North America, system planners will need to ensure that sufficient flexibility is available to operators to offset variability and fuel uncertainty," the report added.
Meanwhile, natural gas-fired on-peak generation has increased in North America from 280 GW in 2009 to 460 GW today, with preliminary plans to add to another 43 GW to 88 GW. Also in the next 10 years, about 45 GW of nuclear, coal, natural gas and biomass generation capacity is expected to retire, which could surpass the total amount of retirements that occurred over the past seven years, NERC indicated in a slide for the presentation.
"The growth in natural gas generation requires continued and coordinated planning to maintain appropriate fuel assurance," NERC wrote. Moura said the Electric Gas Working Group could finalize guidance materials on that topic as early as March 2020.
The report also recommended that NERC study potential risks of battery storage and mitigation approaches to accommodate more of that technology in the future. "Based on data received in the resource information collected to support this assessment, there will be an increase of [bulk power system]-connected storage in the future; this may even be accelerated if the conditions are right," the report said.