Producing new energy sources and reducing carbon emissions is a challenge for everyone and marine renewable solutions are seen to be a key component in reaching that goal.
Recent studies have identified that the vast majority of the UK’s most economically attractive tidal streams are in waters deeper than 40 metres. This depth brings its own challenges.
North Shields based Ocean Flow Energy (OFE) believes its ‘Evopod’ provides the answer to the quest through its moored tidal energy device as opposed to the current alternatives of permanently fixed devices.
OFE has approached the problem from a marine installation perspective and has developed and patented a novel floating tethered platform - Evopod -that significantly reduces the cost of electricity generation from tidal streams. Its semi-submerged, moored turbine device has been developed specifically for deep water with harsh environments.
Successful early trials have led the company to build and start testing a 1/10th scale prototype and to focus its efforts towards the commercialisation of Evopod tidal stream energy conversion technology.
Graeme Mackie said, “We believe that the most effective way of recovering energy from tidal streams in deeper waters is through the deployment of moored tidal energy devices. These are much cheaper to deploy and can weathervane into the prevailing current direction thus extracting more energy from the tidal stream.”
To date developers attempting to exploit these tidal stream sites have been trying to work out how to permanently fix and maintain devices that have to be placed, accessed and recovered in deep water with harsh environments. Solutions that require the use of jack-up barges and dynamically positioned vessels will have difficulty coping with the water depths, fast flowing tidal currents and waves that are present at these tidal sites. The Evopod solution overcomes these problems by avoiding the need for extensive seabed construction activities which are also potentially damaging to the environment.
The annual energy production from a full size Evopod with twin 15m diameter turbines (2.5MW nominal rating) tethered in a tidal current where the peak velocity exceeds 3.5 m/s (7 knots) is 7160MWh. This equates to a CO2 emissions saving of 2930 tonnes per annum. A farm of Evopod covering a seabed footprint of 1km square will support 39 units giving an annual CO2 emissions saving of 114000 tonnes.