At the end of August, the Scottish Government announced that five marine energy developers will benefit from a total of £7.9 million in funding to further develop testing of new wave and tidal prototypes in the seas around Scotland.
The second round of WATERS (Wave & Tidal Energy: Research, Development & Demonstration Support) funding has been released to 'enable Scottish developers and supply chain firms to capture an increased share of the growing international marine energy market,' which could be worth up to £4 billion for the Scottish economy by 2020.
So, what wave and tidal technologies will be funded by WATERS2? What will the projects entail? And what are the prospects for the future development of marine renewable energy technologies in the UK?
Albatern's WaveNET technology, developed by the company's Chief Technology Officer, David Findlay, is made up of a number of modules that are attached together to form the WaveNET array. Each module has a vertical buoyant 'riser' with a node attachment at its base. The riser is 'surface piercing,' with most of its length submerged — and three link arms are attached to the node at the foot and rise at an angle to surface piercing floats.
As David Campbell, CFO at Albatern, explains, the technology also features 'power take off units,' operating at each nodal connection of the riser to the link arms, and at each connection of the riser to the floats — giving a total of six for each module.
"The node is a fully articulated joint, and all the joints are capable of extracting energy from waves passing by the module. The wave energy results in a kinetic movement of the module. This is captured through hydraulic rams on each power take off unit," says Campbell.
"The hydraulic pressure is rectified on the device and is formed in series between rams, creating high pressure and low pressure rings," he adds.
Within the array, generators are sited in the float assemblies on the surface, making them easy to access for inspection. This also means that the generators can be 'sized' to account for the expected sea states and wave energies where the device will be installed. Campbell explains that the generators themselves are 'marinised hydraulic motor/gensets' that create AC power that is 'rectified electrically' to produce DC — which is then taken off the device. For grid connected systems and other AC systems, the DC is then inverted back to meet requirements either onshore or at the point of electrical use (e.g. an aquaculture farm).
Under the auspices of the WATERS2 project, Albatern has been awarded a £617,000 grant towards a cost of designing and building the first WaveNET array, consisting of up to six modules of 7.5-kW or 45-kW rated capacity. An initial module, based on the company's 'Squid 1 device,' will be followed by two more incorporating any necessary improvements identified in the first test phase. A final tranche of three modules will then be constructed — again incorporating any improvements made following the 'lessons learnt' on the earlier modules.
"The project will cover the deployment and performance measurement of the array and allow comparison with extensive theoretical modelling already carried out by Albatern," explains Campbell.
"In building the devices, opportunities to improve the design for efficiency of yield, deployment [or] maintenance, and also opportunities to bring down manufacturing costs will be sought. Already, we can see cost saving from using cast parts where we need many standard components," he adds.
The WaveNET demonstrator will be deployed from late 2012 to late 2013 in a number of phases to measure output in a variety of configurations in different sea states. Pilot sites in aquaculture farms and 'remote communities' will be developed during 2013 and 2014. Campbell believes that 'a significant opportunity exists' for smaller scale devices in aquaculture globally and that smaller devices 'can also support remote island communities.'
Partner relationships are also being developed throughout 2012-13 to progress the development of grid scale devices based around nodes at 75 to 100 kW, building into arrays of up to 10 MW with 'devices in the water' from 2014 onwards.
AWS Ocean Energy
AWS has been awarded a £3.9 million grant towards the total £15.6 million cost of a project to design, build and launch its AWS-III Wave Energy Converter (WEC) at full scale. A 1:9 scale model of the AWS III, a floating device with a rated power output of 2.5 MW, was tested in Loch Ness in 2010, with a full scale prototype planned for deployment at the European Marine Energy Centre in 2014.
According to AWS, the device consists of a 'multi-cell array' of flexible membrane absorbers which covert wave power to pneumatic power through the compression of air within each cell. The cells are inter-connected, thus allowing interchange of air between cells in 'anti-phase.' Turbine-generator sets are provided to convert the pneumatic power to electricity.
A 'typical' device is made up of an array of 12 cells, each measuring around 16 metres wide by 8 metres deep, arranged around a circular structure with overall diameter of 60m. Such a device is capable of producing an average of 2.5 MW from a rough sea whilst having a structural steel weight of less than 1,300 tonnes. The AWS-III will be 'slack moored' in water depths of around 100 metres using standard mooring spreads.
According to Cameron Johnstone, Chief Executive Officer at Nautricity, the 'development ethos' behind Nautricity’s CoRMaT technology was to deliver a tidal energy technology that 'could be held on station without the need for a big, heavy and expensive supporting structure' and produce a turbine that 'considerably reduced complexity' in its operations of capturing energy from the tidal flow and converting this to electricity. The company also believed that efforts to reduce the weight and complexity of such systems would ultimately lower the costs associated with tidal energy power generation.
Johnstone explains that the technology is 'unique' in that it uses axial mounted contra-rotating rotors, with fixed pitched blades, to directly drive a contra-rotating, permanent magnet generator.