Post on 02-Dec-2015
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Wind Energy: Some Basic Facts
C.L. Bottasso
Politecnico di Milano
November 2011
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POLITECNICO di MILANO POLI-Wind Research Lab
Outline
• Basic working principles of a wind turbine, and its anatomy
• Some basic figures
• Trends: the exploitation of off-shore resources
• Wind energy research at the Politecnico di Milano
• Concluding remarks
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POLITECNICO di MILANO POLI-Wind Research Lab
How it Works
Maximum theoretical aerodynamic efficiency = 16/27 ≈ 0.593 (Betz limit)
Aerodynamic efficiency in practice < 0.50
(plus mechanical and electrical losses)
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POLITECNICO di MILANO POLI-Wind Research Lab
Anatomy
(source: GE)
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(sources: reuk.co.uk, geograph.org.uk, coriolis-energy.com)
Gearbox-Based Configurations
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POLITECNICO di MILANO POLI-Wind Research Lab
(sources: wind-energy-the-facts.org, scruss.com, windpowerengineering.com, inhabitat.com, leitwind.com)
Direct-Drive Configurations
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(sources: wind-energy-the-facts.org, eetweb.com, machinedesign.com)
Hybrid Concepts
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Unique Aspects Some differences with respect to aeronautical applications:
• Dimensions: need relatively low cost materials, large volumes
• Reliability/maintenance: performance with simplicity and robustness
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Where is the Wind in Europe
Forecasts of reasonable accuracy: 6% 24 h, 2.5% 2h (ISET)
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POLITECNICO di MILANO POLI-Wind Research Lab
The Energy Mix
• Wind energy cannot have the same importance in all countries
• Different countries should aim at different energy mixes, depending on their specific natural resources
• An integrated efficient network enables the management of the energy mix within each country (time of the day/season) and across borders
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Installed Wind Energy in Europe
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Wind Energy Share in Europe
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Where We Are wrt the 2020 Objectives
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Comparison with Other Energy Sources
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Cost Comparisons
“External costs”: due to effects on environment, CO2 emissions, health
Subsidies: 23.9 G€ non-renewables, 5.3 G€ renewables (2001, source EU)
(source: Vestas)
€cent/kWh
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Trends: Off-Shore Wind
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Off-Shore Wind ◀ Great potential resources
Great technological problems ▶ (logistics, maintenance,
harsh environment)
… great opportunities
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POLITECNICO di MILANO POLI-Wind Research Lab
Some Deep Water Concepts
(source: Deepwater Wind) (source: StatoilHydro) (source: Principle Power)
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POLITECNICO di MILANO POLI-Wind Research Lab
Wind Energy at the Politecnico di Milano
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An Example: the Wind Tunnel
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Turbulence (boundary layer) generators
The Wind Tunnel of the Politecnico Turn-table
13 m
• High speed testing • Aerodynamic characterization (Cp-TSR-β & CF-TSR-β curves)
• Low speed testing with vertical wind profile • Multiple wind turbine testing (wake-machine interaction)
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The First Ever Actively-Controlled Aeroelastically-Scaled Model
Conical spiral gears
Main shaft with torque meter
Pitch actuator electronics
Slip ring
Torque actuator: • Planetary gearhead • Torque and speed control
Pitch actuator: • Zero backlash gearhead • Built-in encoder
Rotor sensor electronics
Radius = 1m
Height = 1.87 m
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POLITECNICO di MILANO POLI-Wind Research Lab
• Wind energy by itself does not solve the energy problem
• However, it can contribute significantly, especially in some countries
• Off-shore wind can alleviate some public acceptance issues (NIMBY: Not In My Back-Yard), and allows for the exploitation of huge available resources
• From the technological point of view, there are many fascinating problems that need to be solved (research) and opportunities for improvement
Concluding Remarks
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POLITECNICO di MILANO POLI-Wind Research Lab
European Wind Energy Association: www.ewea.org Global Wind Energy Council: www.gwec.net
Further Information