The North American Electric Reliability Corp. is altering the way it assesses grid reliability on changes -- such as more renewable resources, power plant retirements and growing amounts of distributed generation -- taking place in the power industry, NERC officials said Wednesday.
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Reduced emphasis on generation reserve margins being done within NERC is one of three points the organization made in its annual long-term reliability assessment, a 10-year forecast on where the power industry should focus to ensure grid reliability.
Other elements include declining reserve margins in New York, Texas and the Midcontinent Independent System Operator, even amid low load growth, and environmental regulations that are creating uncertainty and requiring diligence in reviewing their impact on the power grid.
The long-term assessment notes that natural gas-fired generation makes up 40% of on-peak generation resources, compared with 28% just five years ago, and is projected to reach 42% by 2024. The report predicts an addition of 44,600 MW of gas-fired capacity over the next decade, and pipeline constraints or fuel availability for generators -- particularly those that rely on interruptible transportation contracts -- will grow in importance for power grid reliability.
Existing and proposed rules from the US Environmental Protection Agency, including its Clean Power Plan on which NERC issued a report last week, are expected to result in generation retirements, NERC said. On top of the 20,200 MW of mostly coal-fired generation that was retired between 2011 and 2013, another 44,200 MW is projected to retire by 2024, including some nuclear capacity and fossil fuel generation, the report said.
That retirement projection does not include the potential effect of EPA's Clean Power Plan, which NERC said could result in retirements of more than 108,000 MW by 2020.
Beyond its initial review of EPA's proposed rule to reduce carbon dioxide emissions from existing power plants, NERC said it will provide additional assessments -- one in April and another in December 2015 -- that would incorporate a final rule before states file implementation plans with EPA. A third review, which would examine state implementation plans, is tentatively planned for December 2016.
The growth of solar and wind power can create challenges for grid operators because of inherent swings in output from those facilities, which create the need for more voltage support to maintain grid reliability, NERC said. That support can come from a variety of resources, and as part of its new approach to assess grid reliability, NERC will look beyond the generation reserve margins and its traditional measurements, said John Moura, NERC's director of reliability assessments.
The power grid will need to be more flexible and have greater ramping capabilities to meet changing load dynamics, Moura said during a conference call. The retirement of a 200-MW coal-fired plant and addition of 200 MW of wind generation would not change a reserve margin in a region, but it presents reliability challenges because of the intermittent nature of wind and voltage support that the coal plant provided, Moura explained.
As the power industry becomes more disaggregated and uses more variable generation resources, NERC can no longer hold onto reliability assumptions built on a vertically integrated utility sector, Moura said.
NERC's essential reliability services task force, formed earlier this year to shape how the organization changes its reliability assessments, will help guide the changes in the coming months, he said.