Energy Imbalance Market Year 1 Enhancements

The second phase of the Energy Imbalance Market (EIM) enhancements initiative will address the potential of an EIM-wide transmission rate, flow entitlements for base and day-ahead schedules, the treatment of transfer limit congestion, market power mitigation of transfer limits, and bidding rules on external interties.  The initiative also includes items that were discovered during EIM implementation.



Phase 2

System changes implemented on October 1, 2016 (1) address differences between EIM transfer limits and the scheduling limit; (2) provide dynamic competitive assessment for market power mitigation of EIM transfer limits;

(3) limit EIM transfers into an EIM Entity Balancing Authority Area and subject them to the market power mitigation process; and (4) establish the standard base schedule treatment for e-Tags.


Phase 1

In October 2015, the ISO implemented a greenhouse gas (GHG) flag and cost-based GHG bid adder, which enhanced the capacity test to cover potential imports and exports not tagging to base schedules and used available transmission capacity for Energy Imbalance Market transfers. The administrative pricing rules were also clarified. These improvements met FERC compliance requirements and facilitated NV Energy’s participation in EIM.


Initiative status

Phase 2

    Implementation: October 1, 2016

    FERC approval: September 15, 2016

    Tariff amendment filing: April 28, 2016

    Board of Governors approval: November 4, 2015

Phase 1

    Implemented: October 2015

    FERC approval: February 3, 2016

    Tariff amendment filing: June 15, 2015

    Board of Governors approval: March 26, 2015

Transition period

    FERC approval: October 29, 2015

    Tariff amendment filings: August 28, 2015, January 15, 2015

    Board of Governors approval: January 5, 2015


 Phase 2


FERC filings and orders 

Tariff development

Policy development

Phase 1

The ISO is proposing a series of Energy Imbalance Market (EIM) enhancements for FERC compliance, to meet commitments made during the original stakeholder process and to resolve issues identified during implementation. Phase 1 will focus on improvements that will facilitate NV Energy’s October 2015 entry into the market, which includes creating a greenhouse gas flag, cost based bid adder, bidding rules on external EIM interties and clarifying administrative pricing rules.

  • Jun 15, 2015 Tariff amendment - Energy Imbalance Market enhancements - phase 1 (ER15-1919)
  • Energy Imbalance Market year 1 enhancements phase 1 - implementation
  • Energy Imbalance Market year 1 enhancements phase 1 - papers and proposals
  • WEIM year 1 enhancements phase 1
  • Energy Imbalance Market year 1 enhancements phase 1 - tariff language

Transition period

  • Readiness criteria development
  • Aug 28, 2015 Tariff amendment - implement transition period pricing - Energy Imbalance Market (ER15-2565)
  • Jan 15, 2015 Tariff amendment - EIM transition period prices (ER15-861)
  • Energy Imbalance Market transition period - papers and proposals
  • Energy Imbalance Market transition period - tariff language