Tidal Technology – The Neptune Proteus Mark III
Introduction
An artists impression of the Neptune Proteus Mark III device showing 3/4 front view.
The Neptune Proteus Tidal Power Pontoon consists of a 6m x 6m vertical axis crossflow turbine mounted within a patented, symmetrical diffuser duct and beneath a very simple steel deck and buoyancy packages. 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 simply to the gearbox and generator/alternator on the top of the pontoon with associated valves and electrical processing and control machinery. The power pontoon is easily moored in the free stream, thus 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. Theoretical work and 1/10th, 1/40th and 1/100th scale laboratory experiments suggest an overall efficiency of greater than 45%.
An artists impression of the Neptune Proteus Mark III device cutaway to show internal components including patented shutters and ducting.
A closer look at the technology
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.
Proteus technology generates cost effective renewable energy in shallow water, estuarine environments with minimal environmental impacts; see DTI Atlas of Marine Renewable Sources: Tidal Power Density map [http://www.berr.gov.uk/files/file27755.pdf]. The Neptune Proteus Tidal Power Pontoon has at least five innovations which make a significant technological impact on tidal stream power development and minimise capital and operational costs:
Benefits of the Neptune Proteus device:
- 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.
History and future plans of development
The commercialisation of the Proteus concept is following planned stages of development:
Stage I - 1/40th Scale Testing
Within
the University of Hull’s flume tank (0.3m x 8.0m) a series
of 1/40th scale prototype tests have been conducted.
Proteus Mark I tests were completed in Sept 2006 and the results lead to developing the Proteus Mark II design. Further tests on the Proteus Mark II design were completed in March 2007.
Stage II - Modelling and 1/10th Scale Testing
NRE designed, mathematically modelled, built and tested 1/10th scale Proteus
device on the tidal River Hull and large scale Total Environments Simulator
at the University of Hull. Completed summer 2006.
(Left) Proteus 1/10th prototype during tests in the Total Environment Simulator University of Hull, (Right) Proteus 1/10th prototype during tests in the tidal River Hull.
Example image from CFD modelling.
Stage III - Preparation for full scale demonstrator
Engage design team. Design and mathematically and CFD model full scale tidal
power pontoon and obtain all costs for manufacture. Completed summer 2007.
Stage IV - Full scale demonstrator at Humber St. Andrews site
Build a full scale demonstrator for the Humber St Andrews site. Design
phase expected in Spring 2008, manufacture expected in Summer 2008 followed
by deployment, performance monitoring/testing and environmental impact study.
Stage V - Develop site
Manufacture the array of ten Neptune Proteus devices (1,000 MWhr/year)
and install at the Humber St. Andrews site with full grid connection. Planned
at monthly intervals from January 2009.
