Tidal Technology – The Neptune Proteus NP1000
Introduction
The Neptune Proteus NP1000 showing 3/4 front view.
The Neptune Proteus consists of a 6m x 6m vertical axis, crossflow turbine mounted within a patented, symmetrical Venturi diffuser duct and beneath a very simple steel deck and buoyancy chambers. The Neptune Proteus is designed for estuarine sites which can exhibit powerful currents, yet have the advantages of lower access, cabling and maintenance costs than in offshore environments. The vertical shaft connects to the 1:200 gearbox and generator in the deck housing. The associated valves and electrical and electronic processing and control are mounted onshore, connected by a floating cablebridge. The device is moored in the free stream, minimising environmental impact and operates equally efficiently for both flood and ebb currents. The rotor is maintained at optimal power outputs by sets of computer controlled shutters within the duct and by the variable electrical load. Theoretical work and 1/10th, 1/40th and 1/100th scale laboratory experiments suggest an overall efficiency of greater than 45%.
Neptune Proteus NP1000 cutaway to show internal components including patented shutters and ducting.
Advantages of the Neptune Proteus
Patent image. Key (1) Neptune Proteus Device, (2) Entrance to Bernoulli duct, (3) Bernoulli duct, (4) Shaft, (5) Gearbox, (6) Generator, (7) Exit from Bernoulli duct, (8) Flow shutters/diverters, (9) Duct base, (11) Rotor blade support rings, (12) Vertical rotor supports, (13) Rotor blades and (14) Sutter actuation cylinders.
- Cross Sectional Shape - Neptune Proteus’ square turbine cross-section generates 30% more electricity per unit channel width than circular turbines.
- Estuarine Locations - Advantages include: proximity to grid and demand, absence of wave activity on structure and ease of installation and O&M access. There are at least ten British estuarine sites with peak spring currents of more than 2.5 m s-1 which would support this technology.
- Environmental Impact - Neptune Proteus is a moored system which has minimal impact on environmental energy flows and the largely steel construction is mostly recyclable.
- Patented flow control shutters – NRE have designed and CFD tested the computer controlled flow shutters which increase the impacted length of the flow on the turbine to almost half of the circumference, thus increasing shaft torque and power outputs.
- Operation & Maintenance - All Neptune turbine components are serviceable on site except for the lower bearing which can be serviced and replaced with local dry-docking. The device can be towed to site using a small tug. Overall, Proteus has reduced capital and O&M costs.