Price volatility has trended lower in the western US energy imbalance market and the bulk of trading still occurs in the form of imports from PacifiCorp into the California Independent System Operator (ISO) territory.
California's primary grid operator operates the new structure, which allows trading energy to cover imbalances — real-time deviations in demand and generation from anticipated levels — with PacifiCorp balancing areas in the northwest US and the Rockies.
Imbalance energy imports into the ISO territory remain strong except in periods when the California-Oregon Intertie is congested, vice president for market quality and renewable integration Mark Rothleder said today during the market's transitional committee meeting in Phoenix. The line is the principal conduit of imbalance energy between the ISO and PacifiCorp's northwest balancing area. The line normally can carry 4,800MW in the southern direction but it was derated to 3,200MW-4,600MW in the past two months. Only a fraction of that capacity can move so-called dynamically scheduled imports into California — power flows that can be scheduled in five-minute increments.
Daily imbalance transfers into California's primary grid peaked at almost 6,000 MWh on 6 December, based on the ISO data.
The frequency of imbalance price spikes dropped for most of December but picked up again around late December and early January. But price spikes in the past few weeks are below $100/MWh.
Federal energy regulators since mid-November waived a rule that set imbalance prices at $1,000/MWh when transmission constraints or insufficient supply prevent dispatch of least-cost generation resources. The rule in effect at present sets the price equal to the marginal economic bid — the highest-priced valid economic offer to sell energy.
The waiver is in effect for 14 November 2014 to 12 February 2015. The ISO has asked the Federal Energy Regulatory Commission to apply the waiver retroactively to 1-13 November 2014. The grid operator is filing a request to extend the waiver from 13 February until 1 November. The operator says it needs time to analyze potential problems in spring and summer seasons, despite lower volatility at present.
The ISO still is making the case that the imbalance market is creating benefits for the participants, with those benefits in "hundreds of thousands of dollars on a weekly basis," Rothleder said.
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