Offshore Wind IEEE Boston PES - November 16, 2010
Offshore Wind A high-level overview of offshore wind project development identifying current technologies, challenges, risks and costs. Presented by: Brook Knodel Electrical Group Manager, Mott MacDonald LLC brook.knodel@mottmacinc.com
Discussion Outline Industry Overview Components Turbines/Foundations 33 kv Collector System (Inter-Array Cables) Offshore and Onshore Substations HV Submarine Cable Risks and Obstacles Costs Questions
Industry Overview Wind turbine technology has proven to be one of the most effective sources of renewable energy. By the end of 2009 worldwide capacity reached 159 GW, generating 340 TWh annually. Offshore wind offers many performance benefits versus onshore wind generation including strong, steady winds and proximity to metropolitan centers. Source: WWEA World Wind Energy Report 2009
Industry Overview cont. Over 3 GW of offshore wind installed globally Mainly Europe and UK Roughly 2 GW currently in construction Growth has been exponential with 32 GW targeted for the UK by 2020 and 30 GW for Germany by 2030 Ability to meet these targets limited by several factors Technology Supply Chain Construction Capacity
Industry Overview cont. In North America, several developers are proposing offshore wind along the North Atlantic Coast and Great Lakes. Deepwater Wind, Fisherman s, Bluewater Wind/NRG, Cape Wind Trillium, Great Lakes Offshore Wind, Windstream Energy Developers are jumping into large scale 500 MW+ projects Progress has been slowed due to many factors: Financing, permitting (land rights/boemre), supply chain, infrastructure, regulatory, lack of long-term federal guidance
Components Offshore wind farms have many similarities to their onshore counterparts but the marine environment poses unique technical design challenges. Major components of an offshore wind farm include: Turbines Foundations Inter-Array Cables Offshore Platform Substation/High Voltage Export Cable Interconnection Facilities
Components cont.
Components cont.
Components cont.
Components cont.
Components cont.
Thornton Bank Phase I, Belgium REpower 5 MW turbines (30 MW) Components - Turbines
Turbines cont. Typical types High-Speed Multi-Stage Gearbox (Vestas) Direct Drive PM/Converter (GE, Siemens, Vestas) Multibrid Low-Speed Gearbox (AREVA, REpower) Projects in development now will probably utilize 5+ MW turbines as the technology continues to develop Costs average $2.5M per MW (not installed) Factories are fully booked for the next few years and global capacity is not sufficient for even a small subset of the proposed projects currently in development.
Turbines cont. Manufacturers: Clipper (USA) 10 MW Scanwind 6 MW GE 4 MW Mitsubishi 5 MW Vestas 3 MW * Nordex 2.5 MW* Repower 5 MW* Sinovel 3 MW* Siemens 3.6 MW* Econtechnia 2.5 MW Multibrid/AREVA 5 MW* Enercon 6 MW Darwin 5 MW Bard 6 MW* Rolls Royce 5 MW * - available now
Turbines cont. Typical Dimensions: REpower 5M (5 MW) Doubly-Fed Induction Generator Type Rotor Diameter: 414 feet Hub Height: 328 feet + transition piece Nacelle Weight: 430 tons From sea level to top of rotor blade is equivalent to a 50 story building! Turbines are spaced approx. ½ mile apart to reduce wake effect.
Thornton Bank Phase I, Belgium Foundations Components - Foundations
Foundations cont. Types Monopile (most popular type) Gravity Foundation (previous slide - 10 stories high, 3000 tons!) Jackets (inexpensive and most suitable for deep water projects) Tripods (specialty for some turbine manufacturers) Floating? (currently being developed) Past projects were in shallow waters (60 ft) and current projects are in 100 ft depths. Future projects are planned for much greater depths which will create installation challenges.
Foundations jackets and mono-piles
Foundations tripods and gravity type
Foundations cont. Currently the foundations and turbines are erected using large jack-up barges customized for turbine erection. The depth of water is a limiting factor and alternate means of erection are being investigated for future deep water projects. The east coast has relatively shallow depths along the continental shelf, but current US jack-up barges may not be suitable. Foundation selection is very dependent upon subsurface conditions. In-depth marine geotech studies are essential. Costs range from $2.5M to $4M each (not installed)
Components Inter-Array Cables ABB XLPE Submarine Cable 36kV, 3 core copper conductor with steel wire armor Source: ABB Submarine Cable Systems User Guide
Inter-Array Cables cont. Utilize solid-dielectric 36 kv insulation offshore generator vendors provide a standard 33 kv primary on each generator step-up transformer. Optical fiber integrated for communications. Each cable can collect up to 35 MW of generation. Larger projects require offshore consolidation of multiple feeders. Installed costs are a small portion of the project, but Installation has proven a challenge (over 80% of insurance claims $$ for offshore wind are related to the inter-array cabling). Many installation contractors have gone bankrupt.
Components Offshore Substation Platform/High Voltage Export Cable Barrow Offshore Wind Farm, East Irish Sea, UK Offshore High Voltage Substation Platform
Offshore Platform/Export Cable cont. Necessary for projects larger than 35 MW to consolidate inter-array cable feeders and step voltage up to suitable transmission levels Design Considerations: Weight and real estate are restrictive. Gas insulated designs (GIS) are utilized for 33 kv and High Voltage AC switchgear. Location of the platform is selected to optimize cost of inter-array and export cable installation For projects larger than 200 MW multiple platforms may be preferable/necessary.
Offshore Platform/Export Cable cont. Export cables are solid dielectric XLPE. Not much track record above 245 kv. Long distance submarine cables have high losses and can generate significant VARs necessitating reactors to control power factor. Splices are potential weaknesses so preference is a continuous cable per phase from shore to platform.
Offshore Platform/Export Cable cont. Routing of the export cables requires significant planning. Cable crossings need to be coordinated with the affected party. Existing cables need to be physically protected and crossings need to be perpendicular. Negotiations may impact schedule. Subsurface investigations may show obstacles that need to be avoided (shipwrecks). Closer in to shore, human, fish, plant and animal habitats may restrict access. Typically the shore landing requires directional drilling or sawing. There are heavy duty saws available but they cost $2M to mobilize, $0.1M per day to operate and another $2M to demobilize.
Offshore Platform/Export Cable cont. As projects get larger and further offshore, new voltage source converter HVDC technology is being considered. Standard HVDC converter technology is too space intensive to fit on an offshore platform. VSC converter technology, such as ABB s HVDC Light, can be configured to fit and provides significant benefits at the point of interconnection including enhanced voltage/var support, black start capability and minimal short circuit contribution. Many countries (including the UK, Europe and the United States) are looking into developing offshore HVDC backbones for interconnection of renewable energy and strengthening of regional transmission networks. Current designs accommodate up to 1200 MW per +/-320 kvdc converter although these technologies are new and have not been in commercial operation. (400 MW offshore has been operational) Installing HVDC requires an onshore converter station which can be costly in densely populated regions such as New York City. Lack of HVDC circuit breakers make multi-terminal designs a challenge. Temporary solutions utilize AC CBs as switches. Costs on order of $1M per MW installed (including submarine cable) Source: ABB It is Time to Connect
Offshore Platform/Export Cable cont. Export cable and HVDC technologies represent a lot of risk for the currently proposed projects over 500 MW. There is little or no track record for the submarine cable and converter equipment although many major manufacturers are focusing on bringing these technologies to market.
Components Interconnection Facilities NYPA s Ryan Substation, New York 230 kv Substation
Interconnection Facilities cont. In much of Europe, utilities are required to bring the point of interconnection to the offshore platform. In the United States, the export cable and substation upgrades required to support the project are the responsibility of the developer. Details are defined by the interconnection studies conducted by the region s Independent System Operator in coordination with the interconnecting transmission owner. Costs vary widely based on voltage and the area s ability to accommodate the proposed plant output.
Risks and Obstacles Offshore wind projects face many obstacles to success. Mitigation of these risks becomes a project unto itself. Getting a project from conceptual phase to commercial operation requires coordination and cooperation with investment capital, local and federal government, permitting authorities, engineers, contractors, utilities, vendors, banks, etc. This is true of both offshore and onshore projects. Unlike it s onshore cousin, offshore construction projects are particularly susceptible to the vagaries of weather. All the coordination in the world cannot remove mother nature from the equation.
Risks and Obstacles cont. How will you finance it? (Multibillion dollar projects) Who will buy the electricity? (FIT, PPA) What ships will you use? (Jones Act, St Lawrence Seaway) What labor force? (Jones Act) Where are you going to stage the construction? (Ports) Will your technology survive the conditions? Will political support remain in place? (Federal, State) Will the weather impact your schedule? How will you maintain it?
Costs Compared to onshore wind, offshore wind costs approximately three times as much to install. These increased costs are partially offset by increased efficiency due to steady winds and closer access to metropolitan areas along the coast. Land based wind projects typically require $1.5M per MW investment. Offshore wind costs have been increasing over time as the projects move from shallow coastal waters to deeper regions. Current investment projections vary from $3M to $5M per MW.
Comparative generating costs, base case 2009 start Discounted lifetime cost / production Mid 2010 datum
Costs cont. A typical breakdown of the costs associated with largescale offshore wind: Development 2.5% Permitting, Legal Fees, Preliminary Design, Interconnection Studies, Site Investigation, Land Acquisition Turbine Procurement 40 % Foundation Procurement 10 % Other Supply Costs 7.5 % Platforms, Cables, Substation Equipment Installation and Erection 15 % Other Costs 25 % Owner Management Costs, Contingencies, Bank Fees, Insurance, Interest
Costs cont. Operation and maintenance costs are difficult to project for US projects. Vendors are not regional and there are no experienced ships or crews in existence. O&M Costs, based on what is being done in Europe are $150k - $200k per MW depending on distance from shore and contract conditions. This equates to approximately $0.05 per kwh for O&M alone.
Questions?
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