There are many different designs out there that harness the energy from our oceans’ waves. Wave energy uses the movement of waves to generate electricity. The technology is continually being modified so that it may one day be able to contribute a large proportion of the energy needed to power coastal countries. If the UK were to harness this technology it could supply a lot of power to the coastal towns and villages. Australia, for example, could supply over 60% of its own energy from wave energy alone. It certainly also helps when countries also have over 300 days of sunshine and can harness solar power as well.
How does wave energy work?
Below are three examples of wave energy, technological solutions:
Oscillating water column (OWC)
For OWC technology, it is not the waves that move the turbines directly, but a mass of compressed air that is pushed by these waves. This involves a structure usually located in a breakwater, the upper part of which houses an air chamber (thus the compressed mass of air) and its lower part is being submerged under the water. In this way, the turbine takes advantage of the movement caused by waves, both when they come in and when they go out, and the doubly-fed generator (both by its rotor or mobile part and by the stator or fixed part) to which it is coupled then feeds energy to the grid.
The platforms draw energy from wave power by floating with the rising and falling motion of waves. The floats are attached by arms to a platform that stands on legs secured to the sea floor. The motion of the floats is transferred via hydraulics into the rotation of a generator, producing electricity.
Channelling the wave
A third approach is to use channels near the shore to store the energy in an elevated reservoir. Then as the water flows back out of the reservoir a standard hydroelectric water turbine is used to generate electricity.
Harnessing the power of waves from the seafloor has often been touted as the best possible way. This is because of the lack of disruption to fishing, leisure and shipping that is often caused by surface-based technologies. These seafloor carpets use the turbulence created by the waves above to power pistons and create hydraulic pressure, which can be turned into electricity to power homes, or used for desalination.
UK wave energy development
In the UK, wave energy is classified as part of marine energy, along with tidal energy. This is why in policy terms sometimes these two areas are referred to interchangeably. In January 2012, there was an announcement of the creation of the first Marine Energy Park (MEP) in the south-west of the UK. This will allow the collaboration between the private and public sector to embark on wave and tidal projects from Bristol to Cornwall and the Isles of Scilly.
Wave energy like tidal power is supported by tradeable ROCs. The current level of support is 2 ROCs per MWh of electricity generated. After the 2011, the level of support is to increase to 5 ROCs per MWh. The idea is that for the next few years the UK government needs to support emerging technologies so that they can become the cutting edge solutions of the future. As the technology in this is still developing, the output cost of electricity produced is greater than for fossil fuels. It is for this reason that both UK and Scottish Governments have a large role to play. The Green Investment Bank, when it goes live, is more likely to lend to projects that are close to mass scale expansion rather than funding any research and development stages.
Berkeley, California, and the seafloor carpet
A team including, Reza Alam and Marcus Lehmann, have come up with a revolutionary way of tapping the constant 24/7 power of the wave. Instead of trying to harness the energy from the surface, potentially causing disruption to shipping, fishing and leisure, they have come up with a renewable energy source based on the sea floor. They suggest that just one square metre can power two homes and just 10m of Californian coastline can provide as much electricity as a whole football, or ‘soccer’ as they say over in the States, field’s worth of Solar Photovoltaic Panels.
The idea was first thought of when it was realised that patches of muddy ground found off the coastlines of Northern America, reduced the dominance of waves hitting the shore. The oscillation of the waves would gently push the mud up and down, causing a build up of heat as a result. This turbulence, absorbed by the muddy floor, would be the perfect 24/7 dense form of energy generation.
Double action cylinders, holding a carpet that is currently a thin sheet of rubber in testing but due to change to an alternative durable substance, which are forced up and down by the waves, create hydraulic pressure. This can then be passed along the sea floor and onto the shore where it then can be exchanged and transformed into electricity.
Thought to be made commercially available before 2026, this is certainly the next big thing regarding sustainable, renewable wave technology.
Wave Hub, Cornwall
What is Wave Hub?
Wave Hub is a grid-connected offshore facility for the large scale testing of wave energy technologies. It is located in south-west England, 16km off the north shore of Cornwall (see Figure 1). The Wave Hub concept was conceived in 2003 by the South West Regional Development Agency (SWRDA), the necessary consents for the project were obtained in 2007 and Wave Hub was set up in 2010.
Funding for Wave Hub has come from the SWRDA (now disbanded and under central government control), the European Regional Development Fund Convergence Programme for Cornwall and the Isles of Scilly, and the UK government.
Wave Hub – How It Works
The Wave Hub project holds a 25-year lease of 8km2 of seabed that is split into four separate 1km x 2km berths which the project will underlease to wave energy device developers for an agreed term. The length of tenure for developers is not fixed, Wave Hub expects developers to test the reliability of their machines over a number of years and then build larger, commercial scale projects in the region and elsewhere.
The Wave Hub unit itself is connected to the shore via twin 300mm2 33kV power triads and fibre optic cables contained within an armoured cable running under the seabed (See Figure 2). This cable is terminated within the hub unit that lies on the seabed onto two bus bars, and each bus bar services two berthing areas. Each bus bar has two 300m ‘tails’ composed of a three core 120mm2 33 kV cable that operates at 11kV. There is therefore one ‘tail’ for each berth. The lead device from each wave energy array will connect to the hub via an 11kV dry-mate connector situated at the end of each Wave Hub tail and provide both electrical and fibre optic connection, allowing remote control and monitoring of the wave energy devices as well as electrical transmission.
The cable running from the Wave Hub to the shore connects to a new electricity substation at nearby Hayle that consists of an 11kV/33kV transformer with associated switchgear and power factor correction equipment to ensure within specification delivery to the grid. Initial operation of the Wave Hub system will be at 11kV with capability for 16-20MW of power. Once subsea components that allow 33kV operation are developed by the industry, Wave Hub will be have capacity for up to 50MW devices.
The seabed in the region of Wave Hub’s lease is generally 50m to 60m below sea level, and with the south west peninsula exposed to an excellent wave resource in the form of the prevailing westerly Atlantic swell, the typical range in the Wave Hub location is 15-25 kW/m (kilowatts per metre of wave face). Furthermore the region’s strong 400kV grid that runs close to both the north and south coast of the peninsular, and numerous shallow and deep water ports reduces potentially high costs of necessary infrastructure.
Building Expertise and Research Around the Wave Hub
The nearby Universities of Plymouth and Exeter have joined forces to create the Peninsula Research Institute for Marine Renewable Energy, and with the region’s history of advanced maritime and engineering, Wave Hub is in the vicinity of a skilled workforce complemented by world-class research and facilities that enable the project to fulfil its target of bridging the current gap in the industry between R &D, initial prototypes and full commercialisation.
In addition, RegenSW is the south west peninsula’s very own renewable energy agency that has developed the Offshore Supply Chain aimed at supporting a network of companies active in the offshore energy sector numbering in the hundreds.
Wave Hub Environmental Impact
In terms of the environmental impacts, Wave Hub will oversee a co-ordinated and ongoing programme of environmental monitoring with its customers, and extensive baseline data has been recorded to facilitate accurate determination of any environmental impacts of different devices.
Wave Hub and Developing Wave Energy in the UK
The UK has the largest wave energy resource in Europe, and the feasible resource is approximately 50TWh/year, with a practical potential for up to 1,000MW of installed capacity by 2020 as suggested by several reviews. In the South West specifically, a report predicted the installed capacity could be from 83-285 MW by 2020, with the top estimate being equivalent to £57 million in revenue. The Wave Hub project plays an important role if these figures are to be realised.
Currently Wave Hub have received commitments for two of the berths, one of which is from Ocean Energy Ltd., who have been developing and testing an absorbing air chamber platform for the last 10 years, and Wave Hub expect them to take up residence at the beginning of 2013. Wave Hub have also been receiving plenty of interest and believe there is a strong chance of the other two berths being filled soon.
Agucadoura Wave Farm, Portugal
Agucadoura Wave Farm – Key Facts
In September 2008, following 10 years of design, refinement and testing, 3 Pelamis wave-following attenuation devices were installed 5km off the coast of Aguçadoura, Portugal, creating the world’s first wave energy farm.
Each 120m long Pelamis machine lays semi submerged on the surface of water that has a depth greater than 50m, and is composed of four long tube sections joined together by three power conversion units. The motion of each section flexing relative to one another results in high pressure oil passing through hydraulic motors driving electrical generators which are linked to the grid through cables along the seabed. At a cost of approximately $11.5million, the three Pelamis machines had an installed peak capacity of 2.25 MW, which is enough to power approximately 1,600 homes per year.
Efforts were taken to minimize the impact on local marine flora and fauna through, for example, a mooring system of embedment anchors, chains and ropes rather than more permanent gravity based systems.
Agucadoura Wave Farm Technical Issues
However in November 2008, technical issues resulted in the machines being brought to shore, and although these technical issues were resolved, the financial crisis sunk the Portuguese electricity utility Enersis’ parent company Babcock & Brown, resulting in the project ending much earlier than planned, and before any more of the anticipated 28 Pelamis machines had been built.
Following this disappointment, Pelamis shifted their focus onto a second-generation power generator, the P2. The P2 is longer and heavier allowing greater energy capture at lower cost per MW. The P2 also has a number of design improvements, increasing the efficiency and reliability.
Wave Farm Projects in the UK
There are currently two P2s being tested at the European Marine Energy Centre (EMEC) in the Orkneys, one being owned by E.ON, and the other by ScottishPower Renewables. ScottishPower Renewables have agreed a lease for a 50MW wave farm in Orkney with The Crown Estate that will be made up of 66 Pelamis machines, and the lessons and experience currently being accumulated at EMEC will play a vital role in the success of this plan.
Agucadoura Wave Farm – Next Steps
The Agucadoura Wave Farm, made up of a joint venture between Pelamis and now EDP and Efacec, hopes to receive a new lease of life in the form of a 20MW installed capacity follow-up project with 26 new Pelamis machines. As above, this project is dependent on the outcomes of the P2 testing in the Orkneys.
Portugal are especially hopeful that this follow-up project will be successful as wave power is going to be vital in their ambitious plans for 60% of the country’s energy to be from renewable sources by 2020. Portugal has an extensive coastline, most of which is exposed to the full force of the Atlantic and despite the initial failing of the Aguçadoura Wave Farm, Portuguese energy companies continue to invest in high-tech ocean solutions.
The Severn Barrage – Might It Finally Happen?!
August 23, 2012
I heard some really good news this week that David Cameron has asked for a re-examination of the Severn Barrage business case. This ambitious construction proposal was killed off as a project back in 2010 due to the environmental concerns and soaring costs, but it now appears that it is back on the radar.
First a bit of background though – the Severn Estuary has a tidal range of 14m, the second biggest in the world, making it ideally suited to tidal energy. The idea of using the Estuary to create power was first mooted in 1849 by Thomas Fulljames, but it was not until 1971, when Dr Tom Shaw suggested building the barrage to span the entire length of the estuary, from the Northern Somerset coast up to Lavernock Point in Wales. This proposal was also shot down in the early 70’s due to an abundance of cheap oil making it uneconomical. Over the following years the business case was continually revisited however the soaring prices of the proposed project have always made it unattractive.
So fast-forward to 2012 and what has changed? Well we are in the middle of a massive recession, and the need to create jobs via large infrastructure projects may hold the key to our recovery. The theory is that the proposed Severn Barrage, at a potential cost of £30bn, could be just the type of infrastructure project required to kick-start the economy.
The plan would be to fund the barrage through a consortium of investors rather than through public funding. Although backing from the Government would be absolutely key, as for the project to be economically viable the subsidies available for renewables would need to be available.
Its construction would be the biggest infrastructure project since the channel tunnel, with the potential to create 20,000 new construction jobs and 1000s of operational jobs in the local area when it gets completed.
The UK is also facing an uncertain energy future, with issues regarding energy security and our planned nuclear plans due for decommissioning before the end of the decade. The Severn barrage has the potential to create 5% of the UK’s energy from a clean, predictable, renewable source, with an installed capacity of 8.64GW, producing about 17TWh of electricity per year. Based on an average home using 4800kWh a year, the barrage would provide enough electricity for approximately 3,000,000 homes
By getting such a large proportion of our energy from this 100% renewable energy source, it would also help the UK to hit its emission reduction targets. Also tides are more predictable unlike the sun shining for solar power plants and the wind blowing for wind farms, making this energy source less intermittent.
Opposition to the barrage is still widespread though, due to the Estuary’s unique ecology. The RSPB is particularly against the barrage, as its presence would disrupt the feeding ground of over 85,000 birds, but there are other concerns that it would prevent the easy passage of ships moving up and down the Severn (although the Rance Tidal Power Station in France has locks within its barrage to allow easy passage, so I presume these would be present if the project does go ahead).
My personal feelings are that the Severn barrage is a great idea particularly if this can be funded privately. I know there will be a significant impact on the local environment, but I think the potential for an abundance of clean renewable energy especially at this time where at any moment any of the electricity that we import as a country could be at risk. Creating more energy supplies in the UK by using our unique topography has to be good for our country in terms of enhancing energy security and safeguarding highly skilled jobs in the construction & engineering sectors.
In January 2013, Peter Hain announced that the Severn Barrage could get parliamentary approval by the end of the year, since it has been rethought so there is no threat to fish or birdlife. If approved it could be completed by 2024, helping to supply 5% of the UK’s energy demands. In addition it is thought the new proposal will only be comprised of private funding.
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