CAISO’s Western Energy Imbalance Market has yielded $5.05 billion in benefits for its members since its inception in 2014, continuing the positive trend of growth tied to an expanding Western footprint, according to the ISO’s fourth-quarter benefits report released Jan. 31.  

“This level of economic benefits are a very good representation of the value and effectiveness of the WEIM market to meet supply and demand across the wide footprint,” Guillermo Bautista Alderete, director of market performance and advanced analytics for the ISO’s Department of Market Monitoring, said at a Feb. 6 WEIM Governing Body meeting.  

Q4 2023 produced a total of $391.82 million in cost savings for WEIM participants, accrued from having additional entities join the market in 2023, which now stands at 22 balancing areas representing nearly 80% of the demand for electricity in the Western Interconnection.  

The Balancing of Authority of Northern California saw the largest share of benefits last quarter at $73.24 million, with PacifiCorp second at $50.46. 

CAISO said economic transfers within the WEIM were “substantial” in Q4. The ISO itself had the highest volume of net exports, at 1,403,521 MWh, followed by the Salt River Project (629,470 MWh) and PacifiCorp East (538,108 MWh). Powerex was the largest net importer at 1,266,745 MWh, followed by CAISO with 735,579 MWh. 

CAISO also led in the volume of wheel-through transfers, at 1,140,739 MWh, followed by Arizona Power at 379,452 MWh.  

WEIM also continued to provide emissions benefits due to its ability to enable transfers that prevent renewable output from being curtailed. According to the report, the total avoided renewable curtailment by volume reached 49,880 MWh, displacing an estimated 21,349 metric tons of CO2 in Q4. Avoided curtailment since 2015 yielded a reduction of 925,568 equivalent tons of CO2.  

“The environmental benefits of the WEIM are very compelling, really helping to bend the cost curve for many,” CAISO CEO Elliot Mainzer said during the Feb. 6 meeting. “We see an increasingly volatile system that’s impacted by extreme weather and new resource development. That wide-area capability of the WEIM will continue to produce these tangible economic and environmental benefits.”  

Extreme Weather at Play

January’s extreme cold snap in the Pacific Northwest demonstrated the WEIM’s ability to deliver reliability, CAISO officials said at the meeting. During that weather event, California balancing authority areas were able to transfer energy to Northwest areas struggling to meet demand.  

“The market’s performance in 2023 shows how widespread cooperation among entities in the Western Interconnection reduces consumer costs and quickly sends energy where it’s most needed during stressed weather conditions,” Mainzer said. “The value of that broad transmission connectivity and resource diversity across the West as a reliability support mechanism continues to come into sharper focus.” 

A report analyzing how CAISO responded to extreme weather conditions in the Northwest in January is slated for the week of Feb. 19, Mainzer said.