Harnessing The Power Of The Thames  

ReCharge News has an article on efforts to harness tidal power (and/or river current power) from the River Thames - CoRMaT moves a step closer to taking the plunge in the Thames.

Nautricity’s 3kW Contra Rotating Marine Turbine (CoRMaT) may be small but the company has big plans for the concept. In the grandest version of its vision, hundreds of differently sized models of the turbine — rated up to 500kW — would be sited in clusters along the river from Westminster, in Central London, to Margate, where the Thames Estuary meets the North Sea, as part of a 50MW development.

The project is being developed by the Glasgow-based company with financier Energy Invest under the Thames Tidal banner. The goal is to prove the viability of a “free-floating" turbine in the currents of the longest river in England, and a gigabyte of data has been collected in the first phase.

“This first stage of this project aims to glean an understanding of how a device of this nature — which is unique insofar as it does not have a rigid supporting system holding it to the seabed — would perform in the river environment," says Nautricity chief executive Cameron Johnstone.
The turbine, unlike the majority of its seabed-mounted brethren, is designed to be anchored in place by a single-point mooring line, steering nose-first into the current, guided by its two contra-rotating rotors.

“The Thames is an ideal testing ground because of the intense river use and the wakes and washes generated by vessels that use it, which create a range of cross-dynamics. Early indications from our data are that cross-waves have very little impact on the device’s performance," says Johnstone.

The CoRMaT evolved from a decision by its designer to buck the trend among first-generation tidal turbines to “marinise wind turbines", building broad-bladed machines mounted on heavyweight foundations.

“We wanted to start with a clean sheet in devising a hydrokinetic device purely for a tidal stream,’’ says Johnstone. ‘‘At the same time, we wanted to keep costs down and found that one of the biggest is accounted for by the structural support system, which can be 40% of the total."

Both objectives were met by the contra-rotating rotors concept. The rotors — one of which has three blades, the other four — turn in opposite directions, using the “natural physics" of the flow to balance the turbine in the tidal stream by having the reactive forces of the first rotor countered by the reactive forces in the second. The different numbers of blades on the two rotors prevents one from eclipsing the other in operation, ensuring there is never a “lull" during power delivery, and smoothing output.

The Energy Technologies Institute (ETI) will model the UK's tidal energy resources to improve understanding of the possible interactions between tidal energy extraction systems as they are deployed between now and 2050. ...

The tidal resource project aims to develop models of the whole UK continental shelf that will be used to investigate how energy extraction at one site may affect the energy available elsewhere.
A wide range of possible future tidal stream and tidal range sites, with differing technology possibilities will be represented in the models.

The project will identify how the interactions between different sites around the UK combine to form an overall effect, and what constraints these interactions could place on the design, development and location of future systems.

The models will be made available through a service provided by HR Wallingford to the wider marine industry to help inform future plans and strategies for tidal power.

HOPES have been raised for the future development of marine energy in the Pentland Firth following a multi-million-pound Scottish Government pledge – but questions remain over how exactly it will work.

First Minister Alex Salmond announced on Monday an £18 million commitment to help develop the country’s first commercial wave and tidal power arrays in the firth, Orkney and other Scottish waters.

The money is to be used to take developers from single-test machines to the stage where they have multiple machines in the water.

Caithness and North Sutherland Regeneration Partnership programme manager Eann Sinclair welcomed the news but warned details are sketchy at best. “Any money that goes into the wave and tidal industry at the moment is good news and the fact that the overwhelming focus for the whole of Scotland – if not the whole of the UK – is the Pentland Firth means that we should all be welcoming it," he said.