Tamakoshi V

Summary

Tamakoshi V is a downstream cascade project of Upper Tamakoshi, developed as an under-construction NEA-linked asset with revised capacity figures across registry and NEA/JICA sources.

99.8 MW · under construction · on the Tama Koshi · in Dolakha district. A cascade project of Upper Tamakoshi (456 MW), designed to operate in tandem with Nepal's largest power plant.

Specifications

Sources

• NEA Annual Report FY 2024/25
• JICA IPSDP Final Report Annexes (Vol. 2)

Specifications (NEA / JICA IPSDP data)

The Cascade Model — Paired with Upper Tamakoshi

Tamakoshi V is the first cascade project explicitly designed to operate in tandem with Upper Tamakoshi. At 99.8 MW, it captures energy from the tailwater discharge of the 456 MW PROR powerhouse upstream — effectively extracting additional generation from the same Tama Koshi water that has already passed through Upper Tamakoshi's turbines.

This cascade pairing is structurally significant for three reasons:

1. Hydrological efficiency: Instead of spilling Upper Tamakoshi's tailwater, Tamakoshi V captures it for secondary generation. This is the same cascade principle as the Kulekhani Cascade, but at 10× the scale.

2. Shared transmission: Tamakoshi V plugs into the same New Khimti → Khimti-Dhalkebar 220/400 kV evacuation corridor that Upper Tamakoshi depends on. The corridor's 400 kV GIS building and transformer banks at New Khimti were designed with this combined load in mind.

3. Operational interdependence: Any curtailment, maintenance shutdown, or flood closure at Upper Tamakoshi immediately zeroes Tamakoshi V's inflow. The downstream plant is not an independent asset — it is a rider on the upstream plant's operational schedule. This interdependence is not captured in standalone PPA terms.

The EPF Financing Model

Tamakoshi V is financed by Nepal's Employers Provident Fund (EPF) — the country's largest pension fund. This marks a departure from the commercial bank consortium model that dominates private IPP financing.

The EPF model carries distinct structural implications:

• Long-term liability matching: EPF's pension obligations span decades, making its capital well-suited to infrastructure with long depreciation schedules. Commercial banks struggle with the 15-year tenors typical of hydro lending.

• Lower cost of capital: As a mandatory social security institution, EPF can deploy capital at rates below commercial lending — reducing the project's DSCR pressure relative to commercially-financed IPPs of equivalent scale.

• Public accountability: EPF's investment decisions are ultimately answerable to Nepal's workforce. The financial performance of Tamakoshi V will directly affect millions of pension accounts — a political dimension absent from private bank consortiums.

• Precedent value: If Tamakoshi V succeeds under EPF financing, it establishes a template for domestic institutional capital to fund Nepal's hydropower pipeline without the currency risk and short tenors of international project finance.

The NEA Subsidiary Ecosystem

Tamakoshi Jalvidyut Company Limited (TKJVCL) sits within the same NEA subsidiary architecture that produced Upper Tamakoshi (via UKHLL), but with a distinct developer entity and financing source. The relationship:

The Tama Koshi basin in Dolakha now carries three NEA-linked projects at different delivery stages — from the operating 456 MW anchor to the 650 MW survey-stage aspirational — with Tamakoshi V as the bridge asset connecting current operations to future basin expansion.

Construction Status

As of the NEA FY 2024/25 annual report, Tamakoshi V has reached 15.34% construction progress. Key milestones:

• Contractor's camp near headworks and powerhouse area completed
• Bunker near headworks area completed
• Batching and crusher plant installed and operational
• Road access from Singati Bazar (near Upper Tamakoshi) established

The project's RCOD target under the JICA IPSDP milestone ladder is 2025/2026, though current progress suggests a realistic completion window beyond that date. The NEA annual report lists Tamakoshi V alongside Trishuli 3B (37 MW), Rolwaling (22 MW), and Upper Modi (60 MW) as NEA-linked projects "in different stages of construction."

Transmission and Corridor Risk

Tamakoshi V shares the Tama Koshi transmission corridor with the largest concentration of generation capacity in Nepal. The New Khimti substation — originally sized for Upper Tamakoshi (456 MW) — now serves the entire Likhu cascade (213 MW) plus Tamakoshi V (99.8 MW), for a combined corridor load exceeding 768 MW.

The 200 MVA auto-transformer upgrade completed in late 2023 (which resolved Likhu -2's stranded generation crisis) was a necessary but not sufficient fix. As Tamakoshi V approaches COD, the corridor will face renewed capacity pressure — and the cascade interdependence with Upper Tamakoshi means any upstream NEA dispatch decision directly determines Tamakoshi V's revenue.

Cascade Interdependence and Risk

The tandem operation model — Tamakoshi V catching Upper Tamakoshi's tailwater — is hydrologically elegant but operationally fragile:

• Upstream curtailment: If NLDC curtails Upper Tamakoshi for grid stability, Tamakoshi V's inflow drops to zero. The downstream PPA contains no compensation mechanism for upstream operational decisions by the same NEA that signs both contracts.

• Flood exposure: The September 2024 flood that shut Upper Tamakoshi for 88 days (reducing generation to 67% of design) would have zeroed Tamakoshi V for the same period. Unlike Chilime's snow-fed buffer, the Tama Koshi is a high-discharge monsoon system with extreme seasonal volatility.

• Single corridor dependency: A transformer failure at New Khimti strands both plants simultaneously — 555.8 MW of combined NEA-subsidiary generation offline in a single event. See Buildability and Stranded Generation.

Limitations & Controversies

The page reconciles multiple public capacity figures but still depends on source snapshots for progress, RCOD, corridor loading, and cascade-operation risk; it does not replace updated project-company disclosures, lender reporting, or dispatch data.

See also

• Upper Tamakoshi — upstream 456 MW anchor plant
• Tamakoshi 3 — 650 MW survey-stage project in the same basin
• Koshi Basin — basin context
• Buildability — transmission planning and corridor risk
• Stranded Generation — the evacuation bottleneck problem
• Q-Design Discharge — design discharge and contracted energy
• Khimti–Dhalkebar 220 kV Hydropower Corridor — shared 220/400 kV backbone
• Likhu -2 — same corridor, stranded generation precedent