Interim Mindanao Electricity Market (IMEM)
The Interim Mindanao Electricity Market (IMEM) is a transitional electricity spot market for the Mindanao Grid, directed by DOE through DC2013-01-0001 (9 January 2013) and operated by PEMC/IEMOP. It was established in response to severe power supply shortages and brownouts in Mindanao, and served as a precursor to Mindanao’s eventual entry into the full Wholesale Electricity Spot Market (WESM) [DC2013-01-0001, §2, 2013-01-09].
Origin and Context
By early 2013, the Mindanao grid was experiencing chronic generation capacity deficiencies resulting in rotating brownouts. PSALM and NPC controlled approximately 74.19% of total generating capacity in Mindanao at the time [DC2013-01-0001, §3(c), 2013-01-09]. WESM had been operating in Luzon since June 2006 and in Visayas since December 2010, but Mindanao had not yet joined due to its distinct supply structure and the predominance of large hydro and geothermal plants under NPC/PSALM control.
DOE directed the Philippine Electricity Market Corporation (PEMC) to develop a market design tailored to Mindanao’s conditions — a day-ahead, deficiency-targeting market distinct in scope from the full WESM [DC2013-01-0001, preamble, 2013-01-09].
Market Design
IMEM was designed as a mandatory day-ahead market with the following features [DC2013-01-0001, §2, 2013-01-09]:
| Feature | Description |
|---|---|
| Market type | Day-ahead; participants submit nominations one day before delivery/curtailment |
| Mandatory participation | All generation companies, directly-connected customers, and distribution customers in Mindanao |
| Scope | Addresses only supply deficiencies in the grid (not full bilateral contract settlement) |
| Dispatch mechanism | Merit order table — same principles as Luzon/Visayas grids |
| Real-time balancing | Imbalance correction using merit order table from IMEM operator |
| Pricing | Uniform market clearing price; total costs allocated among IMEM participants |
| Governance | Framework designed to ensure free and fair competition and public accountability |
| Energy efficiency | Incentive mechanisms for contributions to grid supply |
Governance
PEMC was directed to submit IMEM Implementing Rules and timelines to DOE within two months of the DC’s issuance (i.e., by March 2013), for DOE approval. Pending approval, PEMC was authorized to file with ERC for cost-recovery funding [DC2013-01-0001, §2, 2013-01-09].
Agency responsibilities assigned by the circular [DC2013-01-0001, §3, 2013-01-09]:
- NGCP: Grid reliability and security per Philippine Grid Code
- TransCo: Technical support to DOE and PEMC; NGCP compliance monitoring
- PSALM and NPC: Maximize Mindanao generating capacity utilization; PSALM provides O&M financing for NPC plants
- NEA: Prepare Mindanao electric cooperatives for IMEM participation
Transition to Full WESM
IMEM operated as Mindanao’s electricity market until the full WESM Mindanao achieved commercial operations on 26 January 2023 (DC2022-12-0039). IEMOP (which succeeded PEMC as market operator in 2018) managed the transition. RCOA and GEOP in Mindanao followed on 26 March 2024 (DC2024-03-0009).
The IMEM era corresponds to the period when Mindanao electricity pricing was largely driven by NPC/PSALM bilateral contracts rather than competitive spot dispatch.