Influences on the Design and Viability of Large Offshore Wind Farms and their Connection to Shore
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European Union is the world`s leader in offshore wind power. Contributes to Europe`s goal of being competitive in the energy sector. Electricity network are the bone structure of the electricity sector. PS. That's not the full presentation, futher material can be access by email if necessary ny other information, due Slideshare do not upload the file notes.
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Influences on the Design and Viability of Large Offshore Wind Farms and their Connection to Shore
- 1. Influences on the design and viability of large offshore wind farms and their connection to shore EE576 Power system economics, markets and asset management Source: Energy Technology Institute (March 2013) Eduardo E.F Barbosa Aurora B. Foss Scott P. Linkie Steven Nixon Corinne M. Shand
- 2. Introduction • European Union is the world`s leader in offshore wind power • Contributes to Europe`s goal of being competitive in the energy sector • Electricity network are the bone structure of the electricity sector
- 3. Advantages •Reduces the issues of visual impact •Wind energy yield 40% greater offshore Offshore Wind Disadvantages •High costs and greater investment risk •Disturb underwater life •Hard to forecast
- 4. • Sites are moving further from shore into deeper waters • Longer submarine cables and design constraints • Large turbine size Challenges Source: Subsea World News (June 2012)
- 5. • Onshore wind is an established technology, offshore wind still at development stage • Why inflated offshore capital expenditure (CAPEX)? – High initial capital (up to 30-50% greater) – Increased complexity in design due to challenging conditions – Operation and maintenance – Transportation and installation Offshore vs. Onshore Cost Analysis
- 6. • Offshore: 15 - 30% investment Onshore: 2 - 9% investment • What affects the connection costs? – Distance to seabed from holding port – Sea depth – Extreme weather conditions – Specialist offshore expertise – Distance to onshore grid connection • Onshore wind farms generated electricity at a ‘levelised’ cost of £83-90/MWh, in contrast to offshore wind at £169/MWh Grid Connection Costs Source: The Crown Estate (May 2012)
- 7. • Increased competition from turbine manufacturers in new markets, India and China, will quicken rate of cost reductions: – Cost reductions by 2020 are projected at around 10% for onshore and 30% for offshore • Scale for future cost reductions in offshore wind technology larger as onshore wind is matured technology • Substantial offshore cost reductions achieved through : – Larger wind farms create opportunities for economies of scale – Switch to HVDC connections as cable costs reduced – Improvements in foundation design e.g. replace steel with concrete Future Cost Reduction
- 8. • UK – 18 GW by 2020 • Europe – 40 GW by 2020 • China – 5 GW by 2015 • China – 30 GW by 2020 • Japan – four planned offshore projects Prospects
- 9. • Bottom Mounted • Semi-Submersible WindFloat • Floating Turbines • Hywind Spar Buoy Types of Offshore Turbine Sources: Opti-OWECS 1997, WindFloat 2011, DeepWind 2012, Siemens 2008
- 10. • Lack of coordination between state administrations • Fishing and anchoring pose threats to cables • Power output of the wind farm and strength of the local grid • Availability of reactive power • Additional reserve may be required Regulatory & Technical Issues
- 11. Maintenance- Planning Activities Related downtime of major wind turbine components Source: Condition Monitoring of Wind Turbines – SKM, 2006
- 12. • Logistics of transport and accommodation • Consideration must be given to high-seas environmental factors: – Powerful storms – Heavy swells – Highly corrosive salt water – Health & Safety – Adaptations in design which reduce component stress Operation - Challenges and Collaboration
- 13. Areas of learning from Oil & Gas • Replacement of Equipment • Personnel Transfer • Offshore substations • O&M Ports Source: London Array (2013)
- 14. • N-1 Security – Failure of one component – Demand met satisfactorily • How? – Network power flow studies – Carried out prior to every connection Network Security Rules L1 L2 L3 L4 CB2 CB1 CB3 L1 L2 L3 L4 CB2 CB1 CB3 What is N-1 security?
- 15. • Tee-in solutions – Wind farm or hub tee connection • Hub-to-hub connections – Connection between hubs to – form transmission corridors • Intermeshed designs – Offshore grid to split wind – farms between countries Methods to increase security Source: EWEA (2013)
- 16. • Onshore wind currently presents the most valuable renewable generation source to distribution operators • Offshore wind has the potential to rival onshore in the next few years through significant forecasted cost reductions • Deployment further from shore leads to greater energy yield but this is offset with challenging a O & M environment • It is imperative that the connection does not unbalance the network Summary
- 17. • [1] The European Wind Energy Association (EWEA), Wind in our Sails; The coming of Europe’s offshore wind energy industry (2011) [Online]. Available: http://www.ewea.org/fileadmin/files/library/publications/reports/Offshore_Report.pdf Accessed: 09.03.2013 • [2] Ocean Energy Council, Offshore Wind Energy [Online]. Available: http://www.oceanenergycouncil.com/index.php/Offshore-Wind/Offshore-Wind-Energy.html Accessed: 26.02.2013 • [3] N. Haluzan, Renewable Energy article; Offshore wind power- Advantages and disadvantages (16 February 2011) [Online]. Available at: http://www.renewables-info.com/drawbacks_and_benefits/offshore_wind_power_%E2%80%93_advantag Accessed: 26.03.2013 • [4] Renewable UK, The Economics of Wind Power: written evidence, Energy and Climate Change Commitee, United Kingdom, June 2012. • [5] M. MacDonald, Costs of low-carbon generation technologies, Committee on Climate Change, London, 2011. • [6] European Environment Agency, Competitiveness of wind energy, Europe's onshore and offshore wind energy potential: An assessment of environmental and economic constraints, EEA, Copenhagen, 2009. • [7] Global Wind Energy Council , Global Offshore: Current Status and Future Prospects, [Online]. Available: http://www.gwec.net/global-offshore-current-status-future-prospects/. Accessed: 13.03.13 References (1)
- 18. • [8] T. B. W. E. A. (BWEA), PROSPECTS FOR OFFSHORE WIND ENERGY, [Online]. Available: http://www.offshorewindenergy.org/reports/report_026.pdf Accessed:13.03.2013 • [9] Opti-OWECS, Structural and Economic Optimisation of Bottom-Mounted Offshore Wind Energy Converters, 1997. [Online]. Available: http://www.offshorewindenergy.org/reports/report_013.pdf. Accessed : 14.03.13 • [10] P. P. Inc., WindFloat 2011, [Online]. Available: http://www.principlepowerinc.com/products/windfloat.html. Accessed 14 March 2013 • [11] R. D. N. L. f. S. Energy, Future wind turbines go offshore – deep and floating, 2010. [Online]. Available: http://www.risoe.dtu.dk/News_archives/News/2010/1115_DeepWind.aspx?sc_lang=en. Accessed : 14.03.13 • [12] D. Søren Stig Frederiksen, DeepWind, 2012. [Online]. Available: http://www.risoecampus.dtu.dk/Research/sustainable_energy/wind_energy/projects/VEA_DeepWind.aspx Accessed : 14.03.13 • [13] Siemens, Principle of the Drilling Rig for Offshore Wind Stations,2008. [Online]. Available: http://www.siemens.com/press/en/presspicture/?press=/en/presspicture/pictures-photonews/2008/pn2008 Accessed : 14.03.13 • [14] E. W. E. Association, Wind Directions exclusive: Floating turbines by 2020, says Siemens’ Stiesdal, [Online]. Available: http://www.ewea.org/articles/detail/?tx_ttnews[tt_news]=1777&cHash=ec0b6b4b5075989e544fd3d8125a Accessed : 14.03.13 References (2)
- 19. • [15] Turner, Iain. Condition Monitoring of Wind Turbines, Sinclair Knight Merz. Glasgow, UK. 2006. • [16] BVG Associates. Swindon, UK. 2009. Towards Round 3: Building the Offshore Wind Supply Chain. • [17] Delay, Tom. Jennings, Tom, Offshore wind power: big challenge, big opportunity: Maximising the environmental, economic and security benefits, Carbon Trust. London, UK. 2008. • [18] Gillespie, Adrian., A Guide to Offshore Wind and Oil&Gas Capability, Scottish Enterprise. Glasgow, UK. 2011. • [19] Energy Technology Institute, Picture [Online]. Available at: http://eti.co.uk/img/uploads/homepage_slideshow/offshore-wind.jpg Accessed: 26.03.2013 • [20] Subsea World News (June 2012), Picture [Online] Available at: http://subseaworldnews.com/2013/03/21/video-nkt-cables-delivered-biggest-submarine-cable-for- anholt-offshore-wind-project/ Accessed: 14.04.2013 • [21] London Array(2013), Picture [Online] Available at: http://www.londonarray.com/the- project/offshore/substations/:Accessed: 14.04.2013 • [22] S. Davies, Plugging in offshore wind power, 21 May 2012. [Online]. Available: http://eandt.theiet.org/magazine/2012/05/but-where-do-you-plug.cfm Accessed: 21.03.13 • [23] Offshoregrid.eu, Grid Design Options (hub vs radial, tee-in, hub-to-hub) , 5 October 2011. [Online]. Available at: http://www.ewea.org/fileadmin/ewea_documents/documents/events/Project_workshops/5._Jan_d e_decker_offshoregrid_finalworkshop_griddesignoptions.pdf Accessed: 16.04.13 • [24] The European Wind Energy Association, Picture [Online]. Available at: http://www.ewea.org/ References (3)
- 20. Any questions? Source: Energy Technology Institute (March 2013)
Notas del editor
- Source picture [19].
- Today, the European Union is the world ’ s leader in offshore wind power, with 4000 MW installed. This industry will make sure that Europe is the world leader in offshore wind development, which European companies will benefit from [1]. Offshore Wind Energy contributes to Europe ’ s goal of being competitive in the energy sector, energy security and reduction of greenhouse gas emissions [1]. Electricity networks are the bone structure of the electricity sector, and it is important to invest in energy infrastructure in order to transport large amounts of offshore wind energy to the consumption centres [1].
- Advantages: Offshore energy with longer distance from shore reduces the issues of visual impact from land as well as being able to apply new technologies to a greater extent [2]. Offshore wind energy has the advantage of having more frequent and powerful winds, recent studies has shown than the wind blows 40% more offshore than onshore. As a result of this, offshore wind farms can outperform wind energy projects on land in terms of its capacity [3]. Disadvantages: Offshore wind energy turbines need to be able to withstand rough weather and sea conditions, and as a result the construction of the turbines is more complex, which leads to higher costs. This also makes the installation of offshore wind turbines more complex and difficult, and the connection to the grid is more costly than onshore. As a result of this, maintenance will also be more difficult and costly [2]. The investment risk will also be greater for offshore wind farms [2]. Disadvantages of offshore wind energy related to the environmental impact are significantly reduced compared with onshore wind energy, there are smaller issues related to noise and visual impact, than for onshore energy. But, it has been considered that the noise from the turbine could disturb life underwater, affecting fish population and disturb sea life. On the other hand, studies have also shown that the offshore foundations can act as artificial reefs with a resultant increase in fish population from the new food supply. Greater issues related to the impact on fish and mollusc stocks, bird life and seabed sediment [2]. Another disadvantage related to wind energy is that it is hard to predict and forecast wind energy; therefore there must be another energy resource that makes up for potentially short falls [3].
- One of the effects of the innovations made in wind energy technology is that sites are moving further from shore and into deeper waters. This innovation has both advantages and disadvantages. One of the downsides of this is that costs are rising, and that more advanced design is required in construction of the wind turbines as well as longer submarine cables for the transmission of energy to the distribution network is needed [1]. Over the two last decades, the size of turbines in offshore wind has grown considerably. These trends are considered to have a number of important implications for the supply chain. This is because, larger wind turbines means larger components. This impacts the logistic part of building a offshore wind farm, because it forces the supply chain to founding coastal manufacturing and to make sure that another mobility that is not dependant on road/rail transport is provided [1]. Source picture [20].
- Onshore wind is an established technology, while offshore wind is still in early development stage and therefore the overall costs are greater. Why inflated offshore capital expenditure (capex) [4]? Higher capital (up to 30-50% greater); complex design requirements Increased complexity in design due to challenging conditions Operating and maintenance costs: specialist equipment, therefore inflated charges to use it Offshore wind energy turbines need to be able to withstand rough weather and sea conditions, and as a result the construction of the turbines is more complex, which leads to higher costs [3] Lack of competitive supply chain leads to inflated O&M prices – currently oil & gas sector can provide expertise for the service but expensive as niche service Transportation and installation: In addition to the transportation costs on land, there are the costs associated with shipping the turbines out to sea and installing them with specialist equipment Factors affecting cost: wind turbine model ; the greater power rating the turbine (usually this also means the height is greater as higher wind speed captured at greater height) then the higher the cost site deployment location ; discussed next slide, but simply put, the further offshore then although there is greater energy yield the cost is greater as the conditions are more challenging, deeper seabed's etc. size of wind farm ; the more turbines in the farm, the greater the cost but also complexity increases as how do you arrange them to achieve maximum wind capture i.e. so they don ’ t interfere one another
- Grid connection costs make up 15-30% of offshore wind investment costs compared to 2-9% for onshore wind [6]. Costs increase lies in proportion with increase in sea depth of deployment and the distance from the shoreline. What affects the costs? Distance to seabed from holding port: SEE Picture – many of the forthcoming Round 3 seabed licenses to be issued to windfarm developers are over 100km from the shoreline – greater challenge, greater risk, greater costs Sea depth, Extreme weather conditions - Specialist offshore expertise - Distance to onshore grid connection According to 2011 UK estimates, onshore wind farms generated electricity at a ‘ levelised ’ cost of between £83-90/MWh, in contrast to offshore wind cost of £169/MWh [4] However, expensive costs are slightly offset by greater energy yield from offshore systems,, approx. capacity factor 35% [5]. Higher than onshore capacity factor ~ 22-25%
- Competition from turbine manufacturers in India and China could see cost reductions both onshore and offshore markets [5]: Cost reductions for onshore estimated at around 10% by 2020 Significant cost reductions of up to 30% projected for offshore Competition in the wind turbine market will drive down costs – especially in the onshore turbine market and then as the offshore turbine develop technically, competition will grow between the developers in the market. Scale for future cost reductions in offshore wind technology larger than that for onshore technology as onshore has matured [5]. Offshore wind can benefit from increased economies of scale through wide scale deployment, there are many offshore projects in the pipeline. Substantial offshore cost reductions achieved through [5]: Larger wind farms create opportunities for economies of scale Switch to HVDC connections as cable costs reduced Improvements in foundation design e.g .replace steel with concrete
- According to the Renewable Energy Roadmap, published by the UK government, the UK alone is expected to deploy up to 18 GW of offshore wind capacity by 2020 [7]. Europe is expected to install 16.2 GW of offshore wind capacity over the next four years, and the majority of this will be situated in the North Sea [7]. Europe is expected to have around 40 GW installed capacity by 2020 [7]. China has a target of 5 GW of offshore development by 2015, and 30 GW by 2020 [7]. This underlines the previous slides discussion about the future cost reduction of offshore wind technology, the next couple of years it will still be expensive, but by 2020 this cost is expected to have been driven down Japan announced in the spring of 2012 that four offshore projects were planned, including bottom-mounted turbines and floating turbines, with both the spar buoy and semi-submersible options being tested. Japan ’ s narrow continental shelf limits the potential for bottom-mounted North Sea style offshore wind [7].
- The traditional bottom mounted wind turbine, it is securely grounded via a support structure and has few differences from an onshore wind turbine [9]. Semi-submersible wind turbines are stable floating structures, utilising a semi-submerged platform that is partly visible above the surface of the water. It uses a barge type structure secured to the bottom by catenary anchors. This design enables wind turbines to be sited in previously inaccessible locations where water depth exceeds 50m and wind resources are superior [10]. The floating offshore wind turbine concept consists of a long vertical tube that rotates in the water with a vertical axis rotor at the top, a bottom based generator and a seabed fixing system at the bottom. The exciting new 4-year project is called DeepWind and aims to develop turbines producing 20 MW each; it is a collaboration between DTU (Technical University of Denmark) and international partners from both industry and the research community. Studies show that for sea depths exceeding 30-60m, floating structures are more economically feasible than present offshore technology that is based on piled, jack-up or gravity foundations [11][12]. StatoilHydro installed a 2.3 MW Siemens model, known as ‘ Hywind ’ , off the west coast of Norway in 2009. It has a floating platform that is tethered to the sea floor, and it is the movement of the turbine ’ s blades that enables the turbine to be stabilised through a computer program which monitors the movement of the blades and tower [13][14]. Source pictures [9][10][12][13].
- Lack of coordination between state administrations is The main cause for the delays with China ’ s offshore plans. Exploration of wind energy at sea conflicts with other marine economic businesses for two governmental bodies (National Energy Administration and State Oceanic Administration) in charge of offshore wind power development. For successful long-term development a national plan will need to be worked out [7]. Fishing and anchoring pose serious threats to cables, and the risk of damage from these activities often justifies the additional cost of burying the cable [8]. Power output of the wind farm and strength of the local grid dictate the connection voltage, as does the location of the offshore connection points available [8]. If the wind turbines have induction generators then the availability of reactive power in the local network may be a technical constraint. Voltage flicker must be regulated and this can introduce time delays on machine start-ups [8].
- Without a suitable maintenance plan, an offshore wind power station will be unlikely to last the planned lifespan [15]. Parts will need to be regularly replaced, but this will require tremendous effort and is expensive, thus reducing the return on investment [15]. Monitoring framework for wind turbines, in order to point out possible failures in components attached to turbines. Allowing predictability of failures and the annual failure rates [15], this ultimately reduces the risk of catastrophic failure. Some of preventive maintenance procedures common in large wind turbines include: plans considering periodical changes of lubricating oil from the engine that drives the turbines, rotating cleaning blades of the turbines, checking screws, among other steps of equal importance to keep the machines running at full power. Keeping all these maintenance procedures in day will always help a wind turbine to operate at peak performance and helps prevent breakdowns [17]. Maintenance Options [16] [17]: Continuing to purchase from the same turbine manufacturer creates a dependence on wind turbine manufacturers ; currently asset managers advise against over-reliance on wind turbine manufacturers Moving to use a 3rd party service provider causes limited sharing of operational experiences. Starting to share experiences and technical information enables maximisation of the performance of assets Establishing in-house maintenance expertise generates a lack of skilled resource: companies have teamed up with further education institutes to develop a turbine technician course to help address resource limitations
- Onshore Facilities and Transport/Accommodation [16][17]: Wind farms are being maintained from a base at a nearby port. However, as the distance and size of wind farms increase, it no longer become the optimal transportation and accommodation solution. In addition to typical weather and damage, consideration must be given to high-seas environmental factors [16][17]: Powerful storms Heavy swells Highly corrosive salt water Health and Safety Adaptations in design which reduce component stress The offshore wind farm operation is basically remote through a station located near the coast. Thus, the relative risks of these operating systems are mostly linked to weather conditions, conditions of the ocean environment, and solutions in transport and accommodation (logistics), both of workforce, as the replacement of equipment and devices. Health and safety is another risk factor that is extremely important during operation of offshore wind turbines [16] [17].
- High potential areas for minimising risk of operation and maintenance [18]: Replacement of equipment; The O & G sector has years of experience of this service and there is wide array of logistics equipment to carry out this in the North Sea which is where a number of offshore projects have been identified to be deployed. Personnel transfer; O & G employees with high-class record of applying safety standards and knowledge to sector. There is also a across-the-board training programme for technicians Offshore substations; design, construction, project management O&M ports; Placing infrastructure support in strategic locations Source picture [21]
- What is N-1 security: In the event of a fault on an item of plant such as a transformer, is the network designed to handle the extra load that may occur during a fault. E.G. In the diagram there is a fault on the feed from TX2, upon detection, CB3 will be closed and then CB2 will be opened, this will feed the demand required only if the SO has designed the network accordingly. - A system is said to be n-1 secure if it can handle the demand of the network upon failure of one of its items of plant. How? To ensure the network is n-1 secure, SO ’ s will perform simulations of the proposed connection to ensure the network will still be secure, these will include ensuring the demand can be met while also looking at fault levels to ensure ratings of protection equipment will not exceed fault current ratings.
- All of the above methods can be used to aid in the security of supply from wind farms [22]. Tee-in connections are connections to an existing interconnector or planned transmission lines between countries. Hub-to-hub connections is the connection of hubs to form transmission corridors. Intermeshed designs are the construction of an offshore grid. This consists of an interconnector between countries with wind farms connected along the interconnector and substations at intervals. This allows trade between countries while providing the security of offshore substations to allow trade between countries in the need of energy upon a fault onshore or need for demand. This also gives the system operator more flexibility in the event of a fault to shut down any faulty equipment while still providing energy from other wind farms on the interconnector. Network connections [23]. Source picture [24]
- Onshore wind currently presents the most valuable renewable generation source to distribution operators. Offshore wind has the potential to rival onshore in the next few years through significant forecasted cost reductions. Deployment further from shore leads to greater energy yield but this is offset with challenging a O & M environment. It is imperative that the connection does not unbalance the network.
- - Source picture [19].