ECONOMIA BLAVA
I LES DEMOSTRACIONS DE PESCA I ACTIVITATS DE PROMOCIÓ DEL PEIX DE PROXIMITAT
Commercial in Confidence - © Copyright Carnegie Wave Energy Limited 2010
abundant, high capacity, predictable
Australia has an enormous potential resource in wave energy as we are situated along the southern ocean which is largely unhindered by land allowing the build up of waves due to unrestricted fetch. Independent studies have found that the Australian deep water wave resource is in the order of 170 GW of theoretical wave energy. When this is brought into shallow waters, the accessible wave resource that can be
converted to renewable, clean electricity and made available to the grid is believed to be of the order of 17,000 MW. This equates to approximately 35 per cent of Australian’s current energy needs.
Therefore the fundamental message is that a substantial resource is there and remains untapped at the moment.
There are a number of different wave technologies being developed around the world which are trying to economically extract energy from waves, each based around a similar idea but using different approaches. The different technologies that exist include floating structures that are exposed on the surface, where the power generation is offshore; for examples Ocean Power Technologies (OPT) and Pelamis. Carnegie avoids the complexity of offshore power generation by bringing the power generation onshore with a pumping technology. Carnegie’s technology is also fully submerged, rather than sitting on the ocean surface, where it would be more exposed to extreme changes in energy through storm events. Further, there are environmental benefits as CETO is under the surface.
CETO: Technology Overview
Source: Carnegie Wave Energy Limited
A CETO wave facility comprises an array of submerged CETO wave energy capturing devices that pressurise water and, through a subsea pipeline and hydraulic conditioning equipment, transport it to an onshore power generation facility configured from off the shelf hydroelectric turbines.
The novel CETO pumping units are anchored to the seafloor through a standard foundation design and are driven by a spherical Buoyant Actuator (BA) that collects the wave energy and transmits it to the CETO unit where water is pressurised, pumped ashore through subsea pipelines and used to drive hydroelectric turbines to generate emission-free, renewable electricity. The electricity generation systems are located onshore and utilise established and proven technologies in a controlled environment.
The CETO unit itself (to the left of diagram above) is broadly based on a simple single-acting piston pump that utilises the energy transferred through the BA and tether to the pump mechanism. The BA is designed to mimic a molecule of water in an ocean wave, and is slightly positively buoyant, allowing it to follow the movement of other water molecules around their elliptical path. This movement allows the pump piston to fall on the down stroke, under its own weight, and lifts the pump piston on the up stroke, thereby pressurising the water contained in the system.
Unlike other wave energy systems, the CETO wave power converter is fully submerged and produces high pressure water from the power of waves. By delivering high pressure water ashore, the technology allows either zero emission electricity to be produced (similar to hydroelectricity) or zero emission freshwater though the use of standard reverse osmosis desalination technology.
CETO units are fully submerged and permanently anchored to the sea floor. This also assists in making them safe from extreme forces present during storms. They are self-tuning to tide, sea state and wave pattern, making them able to perform in a wide variety of wave heights and in any direction. CETO units are manufactured from steel, rubber and plastic materials and have been proven for over 20 years in a marine environment.
The technology was conceived by Alan Burns in the 1970s. Carnegie has gone through a structured development process, from conceptual development back in the 1999 through to the demonstration of a pilot plant at Carnegie’s Wave Energy Research Facility at Fremantle. Up to four scaled CETO units have been operational offshore of the facility pumping fluid back to the shore, from which electricity and freshwater production has been demonstrated.
The facility on Rouse Head, including an offshore lease area 300m offshore (for the quarter scale units) is leased from the Fremantle Port Authority. Having demonstrated the technology at quarter scale, Carnegie is now utilising the facility for high cycle testing of large scale components ahead of deployment off a single full-scale 200 kW unit off Garden Island, Western Australia. This will enable the flow, pressure and performance of all components to be measured. This autonomous unit will not be connected back to shore, instead dissipating generated power offshore. Once the single unit has been deployed in the next few months, the next stage will involve the commercial demonstration of a 5 MW CETO array, known as the Perth Wave Energy Project that will provide power on to the grid.
The site off Garden Island, between Garden Island Ridge and Five Fathom Bank, was selected after an extensive feasibility study. By being situated behind Five Fathom Bank the larger elements of the waves (10 to 12 metres) have been removed; leaving a more consistent wave climate of between one to 4 meters in height from which CETO extracts energy. With the 20 years worth of wave data from Rottnest and modelling data, Carnegie has a better picture of an available resource, and how their technology (CETO) will interact with that resource. The Perth Wave Energy Project is partly funded by the Western Australia Government through a $12.5 million grant awarded to Carnegie under the Low Emissions Energy Development (LEED) Fund.
This is the first step in the commercial demonstration of the CETO technology. Beyond the 5 MW Perth Wave Energy Project, Carnegie will commercially demonstrate its technology at large-scale, 15 to 20 MW, from which economies of scale and cost-competitiveness can be demonstrated. Carnegie forecasts that by 2020, approximately 1,000 MW of CETO wave energy capacity could be installed along the southern coastline of Australia, contributing 2.6 per cent of Australia’s forecast electricity needs and equivalent to approximately one eighth of the Australian Government’s 20 per cent RET.
In the last couple of years, Carnegie has acquired sites across Australia for commercial demonstration purposes. It is also assessing international sites, particularly in Europe and the United States where there is strong support for wave energy development.
International projects include development partners EDFEN (Énergie de France - Énergies Nouvelles) which is a large utility company supporting the development of projects in the Northern Hemisphere. This also involves a French government grant of €3 million for a project in La Réunion, which will follow Garden Island. Carnegie has also secured a Canadian government grant for a similar amount for projects on the West Coast. These sorts of projects are aimed at larger-scale commercial demonstrations, but what it comes down to is which site and project will be more economic.
DISCUSSION
Panellists:
Tim Sawyer Graeme Medhurst
Question: You are obviously using water within the closed-loop system. Are there other fluids that are less viscous, maybe some sort of hydrocarbons?
Response: The fluid we’re currently using is based on fresh water, with two per cent to five per cent dosing (chemicals) to control corrosion and viscosity. We are looking at other solutions in trying to gain maximum efficiency from the pipeline, and that is an ongoing process. Initially we’re concentrating on a much more benign fluid; we’re trying not to push the boundaries too far in that respect.
Question: European studies on wave energy is $6.5 million to $13 million per megawatt for prototype equipment, so I’d like to get your comments on what you think the eventual installed costs will be in competing with other renewable energies? Does inclement weather such as, storm wave heights and impacts, impose very large constraints on design?
Response: In terms of the installation, we’re projecting $6 million to $7 million per megawatt installed in the long-term; but initial projects would be above that. For example the first project won’t be competitive in normal commercial terms. In terms of power generation, we’re looking at about $150 per megawatt hour. In terms of the revenue we need to make a project viable, and there have been independent studies which have confirmed that that is reasonable for wave energy, and that it is competitive with other forms of renewables.
In terms of storms, part of what we’ve been working on is a relief mechanism to allow the units to continue operation when the waves get above a certain wave height, in this case four metres; and also by allowing components of the unit to move with the waves. We’re limiting the forces that are going to the CETO unit itself. In regards to extreme wave climates, and there are a few places around the world where 18 metre wave heights have occured, it is all about site selection and developing the technology accordingly with the loads that you expect to sustain.
Question: Intermittency is a key issue with renewable. Has your testing since the project went forward given you any more data on how intermittent wave power will be?
Response: From the initial modelling we’ve done, we are predicting an availability or capacity factor of 55 per cent to 60 per cent; 97 per cent of wave energy is available to us as a resource (between 1 to 4 metres high) on sites around the southern coastline of Australia.
Response: A very interesting characteristic of wave energy is that it is predictable to the extent that we can predict waves a week in advance. As a result we don’t have to respond immediately to bring reserve power on, we can plan ahead if we know how much power we’ll get out of a wave energy system a week in advance. If we get a lull in the wave energy coming into the site, we’ll know about it well in advance; whereas by comparison, wind energy is something that will fluctuate quite unexpectedly.
Response: Through the scale of testing we’ve done off Fremantle, we’re now building a full-scale unit and putting it in the water, where we’ve had a wave buoy out for a year which has been determining the availability of the resource; so the performance testing is what’s next to verify at full scale what we have seen at scale.
Question: Many of the shorelines are in countries that have a water crisis or are facing one in the future, like here in Western Australia. You mentioned that it has the capability to produce desalinated water, I wonder if you could tell us a little more about that.
Response: To date Carnegie’s been focused on power generation, largely because we have to pick whether we look at power or water, and the support mechanisms are there for power. Whichever one we choose, it’s all about demonstrating the performance of the CETO units themselves. In terms of desalinated water, with 40 per cent of the world stressed for fresh water there’s no question we’re in need of a way to sustainably provide fresh water. CETO, a pumping technology pushing high-pressure fluids to shore, lends itself to direct desalination; whether that be for the fluids directly being used to push through membranes, or whether that be through pressure exchanging into a secondary mechanism, or even at the most basic level using electrical power generated by CETO to power a desalination plant. All ways, it lends itself to water production with zero emissions using a renewable resource, and that’s something we’ve been working heavily on in the last three to four months in trying to bring that forward. We recognise that as a key opportunity for CETO.
Question: With your data so far, have you had any experiences as to whether wave energy works well on summer days?
Response: There has been a lot of global wave monitoring. Waves are seasonal to an extent. In Western Australia, the waves off Rottnest don’t tend to drop below a metre, even in summer. So there is always power generation potential throughout the year, but the level of power generation potential will vary clearly with seasons.
Response: It comes as no coincidence that the resource of wave energy is well-matched to the resource of wind energy, because waves are driven by wind; but the patterns will change geographically, so we need to choose technologies that match our resource availability.