Hydrostatic Pressure Machine (HPM)

Resource and requirement

  • Unused low head potential in England: 800 → 1000 MW
  • From old mills and river weirs, (~ 30,000 mills were in operation in the 1850’s)
  • Global resource available from run of river sites to irrigations canals
  • No economically viable very low head and high flow rate machine currently available
  • New requirement for an economic and ecologically acceptable turbine

Concept – Hydrostatic Pressure Machine (HPM)

Concept of the HPM

Members of the sustainable energy research group  (Gerald Muller, James Senior, Nick Linton and William Batten) have been involved in the design and development new machine.

This new machine developed at Southampton University, uses hydrostatic pressure difference. It is a simple machine which can feasibly take a high volume of flow and also also fish as sediment passage.

The further development and field demonstrations has been a part of the HYLOW project.


Theory predictions

The novel principles:

  • Wheels acts as weir and maintains head difference
  • Hydrostatic pressure acts on moving wheel blade
  • Pressure head reduces with increasing wheel speed
  • Losses caused by turbulence, and leakage

Theoretical properties:

  • Efficiency reduces with increasing flow rate (Q)
  • Maximum efficiency does not coincide with max. power
  • Flow volumes Q = 2 m³/s • m
  • Power: 5 → 150 kW
  • Efficiencies: 70 → 85%

 Lab model experiments

One of the configurations tested at Lab scale

 Lab scale model:

  • Most tests done at 1:6 scale
  • 12 bladed machine
  • Used to further develop theory and design field installations

 Parameters tested:

  • Hub to diameter ratio
  • Blade shape / angle
  • Machine to channel width
  • Shoe shapes





Field demonstration (1) Reactivation of old mill

Reactivation of a Mill at Partenstein, Germany with a HPM.

(A) Retrofit of an old mill to generate electricity

(B) Inclined blades, steel runner with concrete support structure

 Measured performance

  • Mech. efficiency: 80%
  • Total eff. (hydro → elec): 65%
  • Measurements agree well with theory


  • Economical
  • Ecologically compatible allows for sediment and fish passage
  • Retrofit possible




Field demonstration (2) Run of river installation

Run-of-river plant, with fish pass, installed River Iskar, Bulgaria


  • Pmax = 12 kW (elec.)
  • H = 1.00 m
  • Q = 1.80 m³/s
  • Max. eff. hydro→ elec: 77% ~ 60% design flow

Further details




Posted in July, 2013