By Robert Mullin
CAISO hauled in the largest share of the $39.52 million in benefits produced by the Western Energy Imbalance Market (EIM) during the second quarter, the grid operator said in a report released Monday.
The ISO was also the market’s dominant exporter of energy over the period as California coped with combined surpluses of solar and hydroelectric output on its system after a wet winter.
CAISO took in $15.49 million in benefits, compared to $8.81 million for PacifiCorp, $8.13 million for Arizona Public Service and $2.47 million for Puget Sound Energy. NV Energy’s estimated $4.62 million in benefits did not include data for June, which is still pending verification.
The EIM’s total benefits increased by $8.52 million — or 27% — over the first quarter. (See CAISO EIM Exports Rise With Spring, Report Shows.) That spread will increase with the addition of NVE’s June figures.
The gross benefits represent either cost savings for serving load or increased profits from merchant operations within the EIM’s participating balancing authority areas (BAAs). The market’s ability to reduce curtailments also enables participants to collect renewable energy credits that would not otherwise be issued.
The benefits calculation nets out inter-BAA transfers that were scheduled ahead of the EIM’s 15- and five-minute market runs to avoid attributing contracted flows to the market.
CAISO exported more than 1.11 million MWh of electricity in the EIM’s five-minute market during the quarter, the report shows. Most of that energy was transmitted into NVE’s territory to be wheeled into the PacifiCorp-East area, but APS also absorbed a significant portion. The inclusion of APS and PSE last October greatly increased the transfer capability within the EIM, improving California’s ability to move its solar surpluses into other areas of the West.
That export capability enabled CAISO to avoid curtailing 67,055 MWh of renewable output from April to June, displacing 28,700 metric tons of CO2 emissions , the report said. The ISO estimates that, since 2015, avoided curtailments from EIM operations have reduced carbon emissions by 204,941 metric tons, the equivalent of removing more than 43,000 passenger cars off the road for a year.
CAISO’s exports are likely to decline sharply this summer as California absorbs more of its own renewable output in the face of increased summer loads, a pattern seen last year. (See PacifiCorp Increases Share of EIM Benefit in Q3.)
The report also noted the EIM’s impact on the procurement of flexible ramping capacity, which represents resources capable of responding to the variable output of renewable generators.
Because variability can decrease in one BAA at the same time that it’s increasing in another, the EIM enables participants to share flexible resources — allowing each BAA to procure fewer resources than would have been necessary on a standalone basis. These “flexible ramping procurement savings” during the second quarter represented about 39% of what would have been the total requirement of the participating BAAs absent the EIM, the report showed.
The EIM has yielded $213.24 million in gross benefits since commencing operation in November 2014 with PacifiCorp as its first member.
