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Pumped Storage Hydro Round-Trip Efficiency Calculator

Pumped Storage Hydroelectricity (PSH) is the dominant utility-scale grid energy storage technology worldwide, accounting for over 90% of global long-duration energy storage.

Elevation difference between upper and lower reservoir water surfaces.

Usable water volume in upper reservoir.

Combined motor, pump, and transformer efficiency.

Combined turbine, generator, and transformer efficiency.

Hydraulic friction head loss in penstock and tunnels.

Calculated Result
75.3%

Round-Trip Efficiency (RTE)

Available Generation Energy

3824.6 MWh

Pumping Energy Required

5076.7 MWh

Volumetric Energy Density

0.76 kWh/m³

Calculation Breakdown

  1. E_gen = ρ·g·V·(H - h_f)·η_t3824.6 MWh
  2. E_pump = ρ·g·V·(H + h_f) / η_p5076.7 MWh
  3. RTE = E_gen / E_pump75.3%

What Is the Pumped Storage Hydro Round-Trip Efficiency Calculator?

Pumped storage hydro stores surplus grid electrical energy as gravitational potential energy of water.

Round-trip efficiency measures the ratio of net electricity generated during discharge to the electricity consumed during recharge.

How Does the Pumped Storage Hydro Round-Trip Efficiency Calculator Work?

Computes effective net head during generation (gross head minus friction loss).

Computes required total dynamic head during pumping (gross head plus friction loss).

Calculates total MWh energy generation, pumping energy consumption, and RTE percentage.

Pumped Storage Hydro Round-Trip Efficiency Calculator Formula & Variables

The core mathematical equation utilized by this calculator is expressed as:

E_{gen} = \rho g V (H - h_f) \eta_t, \quad E_{pump} = \frac{\rho g V (H + h_f)}{\eta_p}, \quad \eta_{RTE} = \frac{E_{gen}}{E_{pump}} = \eta_p \eta_t \left(\frac{H - h_f}{H + h_f}\right)

Gravitational potential energy balance accounting for hydraulic friction losses and electromechanical conversion efficiencies.

How to Use the Pumped Storage Hydro Round-Trip Efficiency Calculator

  1. Enter gross elevation head in meters.
  2. Enter active reservoir water volume in cubic meters.
  3. Specify pumping and turbine generation efficiencies and penstock friction head loss.

Step-by-Step Example Calculation

5 Million m³ Mountain PSH Facility

Input Values:

grossHeadM:320
activeStorageVolumeM3:5000000
pumpEfficiencyPct:88
turbineEfficiencyPct:90
penstockFrictionHeadLossM:8
Worked Steps: High-head closed-loop pumped storage facility with Francis reversible pump-turbines.

Understanding Your Result

Typical modern PSH facilities achieve round-trip efficiencies between 70% and 82%.

Generation capacity indicates the total MWh available for continuous dispatch.

Factors That Affect the Result

  • Head-to-length ratio (H/L): Steep mountains with short penstocks minimize friction losses and capital cost.
  • Pump-turbine type: Reversible Francis units offer compact cost, while ternary sets (separate pump and turbine) switch modes faster.

When Should You Use This Calculator?

  • Feasibility screening and sizing of pumped storage hydro projects for renewable grid integration.
  • Comparing long-duration storage economics against battery installations.

Assumptions & Limitations

  • Assumes constant water level in reservoirs without dynamic water head drawdown curves.
  • Neglects evaporation and seepage losses.

Frequently Asked Questions

Calculation Accuracy & Reference Note

Standard hydraulic potential energy formulation with exact friction head adjustments.

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