CAISO considers tweaks to flexible capacity rules as duck curve grows
- California's grid operator is considering altering flexible capacity requirements that are not sending proper pricing signals, Platts reports, and has launched a stakeholder process to examine must-offer obligations.
- Because California is pushing for 50% renewable energy by 2030, the ISO is predicting oversupply conditions may become common during peak solar times, according to a fact sheet on the issue.
- The ability to quickly ramp generators up and down to match load and renewable power is one of the major challenges in reliably integrating more clean energy. In evenings, as the sun sets and demand picks up, the California grid operator must dispatch about 11,000 MW to meet demand.
Platts has the details on changes being considered by the California ISO to the alphabet soup that makes up its flexible resource products. The grid's flexible resource adequacy criteria must-offer obligation (FRAC-MOO) runs alongside utility requirements to acquire more flexible capacity.
A FRAC-MOO web conference is planned for Dec. 5. According to a presentation posted online, the next steps are for the ISO to consider enhancements to the flexible capacity product that increase the overall availability and ramp rate of the flexible capacity fleet, while reducing the minimum operating level of flexible capacity resources."
The California ISO says it has run analysis from 2012 through 2020 to understand changing grid conditions. Among the challenges are short and steep ramps "when the ISO must bring on or shut down generation resources to meet an increasing or decreasing electricity demand quickly, over a short period of time."
A key to matching renewable generation to demand is to avoid the possibility of negative wholesale prices, where generators must pay utilities to take energy.
"Oversupply is a manageable condition but it is not a sustainable condition over time — and this drives the need for proactive policies and actions to avoid the situation," the ISO said in its fact sheet. "The ISO needs flexible resources with the right operational characteristics in the right location."
According to a recent report from consultancy ScottMadden, California's imbalance of mid- and late-day load, sometimes called the duck curve, is growing faster than expected. The report found that net load, or the belly of the duck, is “significantly lower” in 2016 than forecasted.
Ramping hours, were also greater than expected, with the three-hour ramp exceeding 5,000 MW 58% of the year in 2015, up from 6% in 2011.
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