By Jason Fordney
Energy Imbalance Market (EIM) transfers out of CAISO were on the upswing in March, re-establishing a pattern first seen last spring as California’s growing solar surpluses turned the state into a significant exporter of renewable energy.
Real-time transfers out of CAISO were 243,908 MWh during the month, up more than 60% compared with February and March of last year, according to the ISO’s first-quarter EIM benefits report. Last year’s totals do not include transfers into Arizona Public Service, which began participating in the EIM in October 2016.
Normally heavily dependent on imports, the ISO’s balancing area first became a significant exporter of renewables through the EIM early last year. (See CAISO EIM Boosts Market for Renewables in Q1.)
The report also showed that the EIM last quarter saved its participants $31 million through more efficient generation dispatch and reduced greenhouse gas emission by 23,000 metric tons through avoided curtailments of renewables.
CAISO compares the cost savings of EIM dispatch to the same amount of real-time load imbalance in each balancing authority that would have occurred without transfers between them. The market optimizes generation both within and between regions in the 15-minute market and real-time dispatch.
“A significant contributor to EIM benefits is transfers across balancing areas, providing access to lower-cost supply, while factoring in the cost of compliance with greenhouse gas emissions regulations when energy is transferred into the ISO,” CAISO said.
Benefits can either be cost savings, profit or a combination, and now reach electricity consumers in Arizona, California, Idaho, Nevada, Oregon, Utah, Washington and Wyoming.
The EIM also reduced curtailment of renewable energy resources by about 53,000 MWh. That was down from avoided curtailments of about 113,000 MWh in the same period a year ago, a development the ISO is still investigating but says could be attributed to improved hydroelectric conditions in the West and advancements in how EIM participants are deploying their resources. (See Spring Oversupply Lifts CAISO Curtailments.)
The market also reduced “flexibility ramping reserves” by almost 399 MW in the upward direction and 488 MW in the downward direction, CAISO said.
The EIM has been growing since its launch with PacifiCorp as its first participant in November 2014, followed by NV Energy, Puget Sound Energy and APS. This October, Portland General Electric is due to begin participating, with Idaho Power following in April 2018; Seattle City Light and Sacramento Municipal Utility District in April 2019; and Salt River Project in April 2020.
Total EIM cost savings are $174 million since the market was launched, according to the ISO. Savings grew from $8.1 million in January to $10.4 million in February and $12.6 million in March.