KitVes Project. Controlled airfoils for vessel on-board energy production. Mario Milanese and Lorenzo Fagiano Modelway Politecnico di Torino

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1 Project Controlled airfoils for vessel on-board energy production Mario Milanese and Lorenzo Fagiano Modelway Politecnico di Torino OPTEC, Katholieke Universiteit Leuven, May 26,

2 2 Outline Motivation High-altitude wind energy generation using tethered airfoils Theoretical and numerical analyses Capacity factor estimates Experimental results The KitVes project

3 3 Global total primary energy supply (TPES) in GWh (Source: IEA/OECD) Coal (26% TPES) Oil (34% TPES) Gas (21% TPES)

4 4 Global total CO 2 emissions in Gt (Source: IEA/OECD) Coal (42% CO 2 ) Oil (38% CO 2 ) Gas (20% CO 2 )

5 5 Fossil sources covered 81% of TPES in % of this amount has been used for power generation and 23% for transport 43% of the global carbon dioxide emissions in 2006 is related to power generation and 23% is related to the transport sector Road transport accounts for 20% of global CO 2 emissions, while maritime transport accounts for 2% Global CO 2 emissions should be reduced by 75% in 2050 to keep the global temperature increase below 2.5 w.r.t. pre-industrial equilibrium (source: IPCC) Current renewable energy technology shows little potential to reach this goal, due to high cost, non-uniform and intermittent availability, low energy density per unit area

6 6 Wind energy Recent studies (Archer and Jacobson, J. Geophys. Research, 2005) showed that 100% of the world s energy demand could be supplied by global wind power. Share of wind energy in 2006: <1%. The actual wind technology is not able to exploit the potential of wind power. Wind towers require heavy foundations and huge blades and they can operate at a maximum height of about 150 m (weaker and more intermittent wind) Their power density (MW/km 2 ) is about times lower than that of large thermal plants. A wind farm is able to produce an average power which is a fraction only of its rated power, about 35%-40% for good sites

7 7 Outline Motivation High-altitude wind energy generation using tethered airfoils Theoretical and numerical analyses Capacity factor estimates Experimental results The KitVes project

8 8 KiteGen project Key idea: to harvest high altitude wind energy with the minimal effort in terms of generator structure, cost and land occupation. Concept of late 70s, being recently investigated by few research groups in the world (Italy, Belgium, The Netherlands, U.S.) thanks to advancements in Control and Optimization Theory

9 9 KiteGen project Replace the outer part of a turbine blade with a light airfoil Light structure, reduced cost Able to capture wind up to 1000 m above ground (stronger and more constant) Kite Steering Unit (KSU) Easy scalability due to reduced structural issues

10 10 Energy generation cycle KG-yoyo configuration KG-carousel configuration How much energy can be obtained with such a technology?

11 11 Outline Motivation High-altitude wind energy generation using tethered airfoils Theoretical and numerical analyses Capacity factor estimates Experimental results The KitVes project

12 12 Theoretical and numerical analyses of KiteGen First investigations: M. L. Loyd (1980)

13 13 Theoretical and numerical analyses of KiteGen From Loyd simplified equations and further analyses for fixed KSU (see e.g. Houska, master s thesis, 2007, Houska and Diehl, ECC 2007, ) ( θ ) cos( ϕ ) P ; C W sin r& r& x with C = ρ ACLG G CL and G = C D Adcr cos C L C D 1+ 4AC D Nominal wind W x X Z Fixed KSU ϕ θ r Y Kite Such (static) equations don t take into account the systems dynamics

14 14 Theoretical and numerical analyses of KiteGen Numerical simulations: system model equations (original kite model: Diehl, Ph.D. thesis, 2001) F L W e F c F L mg F D d ψ l Aerodynamic forces Gravity Apparent forces Line drag and weight x& ( t) = g( x( t), u( t), W ( t), r& ( t), W ( t)) with x( t) = [ θ ( t) ϕ( t) r( t) & θ ( t) & ϕ( t) r& ( t)] 0 ref t T

15 15 Theoretical and numerical analyses of KiteGen

16 16 Theoretical and numerical analyses of KiteGen Numerical simulations: energy generation cycle and control strategy Traction phase Passive phase X KSU Z Y Wind direction Model Predictive Control techniques are applied to: keep stability of the airfoil maximize the net generated energy satisfy physical constraints (keep the kite far from the ground, avoid line entangling)

17 17 Theoretical and numerical analyses of KiteGen Wind shear model using wind data* collected at De Bilt (NL) Winter months Summer months * Wind data taken from the NOAA/ESRL Radiosonde Database:

18 18 Theoretical and numerical analyses of KiteGen

19 19 Theoretical and numerical analyses of KiteGen

20 20 Theoretical and numerical analyses of KiteGen Numerical simulations: results Gen. power (simulation) Gen. power (theoretical) Gen. power (theoretical no cables) Gen. power (average) kite area: 500 m 2 overall efficiency: 10.8 lift coefficient: 1.2 approx. wind speed: 9 m/s Numerical analyses can be employed to study the system scalability

21 21 Winter months Summer months

22 22 Outline Motivation High-altitude wind energy generation using tethered airfoils Theoretical and numerical analyses Capacity factor estimates Experimental results The KitVes project

23 23 Statistical analysis of wind data and Capacity Factor of KiteGen KiteGen power curve * Due to wind variability, a wind generator is able to produce in average only a fraction of its nominal power, denoted as Capacity Factor : P = P CF ave max Wind tower power curve taken from

24 24 Statistical analysis of wind data and Capacity Factor of KiteGen Statistical analysis of wind speed* and CF estimation De Bilt (NL) m m Linate (IT) m m Linate (IT) De Bilt (NL) Misawa (JP) Nenjiang (CN) Port elizabeth (ZA) Bodø (NO) * Wind data taken from the NOAA/ESRL Radiosonde Database:

25 25 Outline Motivation High-altitude wind energy generation using tethered airfoils Theoretical and numerical analyses Capacity factor estimates Experimental results The KitVes project

26 26

27 27 Experimental results and model validation Test performed in Sardegna (IT), in September Turbulent wind of about 3-4 m/s at ground level. Kite effective area: 5 m 2, maximum line length: 300 m Simulated Measured Simulated Measured

28 28 Experimental results and model validation Test performed near Casale (IT), in January Wind of about 1-2 m/s at ground level. Kite effective area: 10 m 2, maximum line length: 800 m Simulated Measured Simulated Measured

29 29 Outline Motivation High-altitude wind energy generation using tethered airfoils Theoretical and numerical analyses Capacity factor estimates Experimental results The KitVes project

30 KitVes project 30 To harvest powerful wind in the troposphere and transform it into electrical energy To generate power commensurate to the vessel requirements for auxiliary services, traction or both To provide automatic optimization of the balance between the amount of generated energy and the traction/drag forces w.r.t. the direction of the vessel To avoid collisions between two or more of such systems working in the same area To implement automatic take-off and landing of the airfoils

31 31 KitVes project High-altitude wind energy will be produced on board of a prototype boat Such wind energy won t be employed only for direct traction, but also to supply electricity for the boat This way, a brand new concept of on board electric generator will be investigated, whose generation capabilities are essentially independent from the navigation conditions

32 32 Naval application of the concept: energy generation + ship traction Θ γ kite Analyses for vessel on-board energy production v b KSU γ * = Θ 2 ( 0 sinθ cos( γ ) & b cos( γ )) & b cos ( γ ) P = C W Θ r v r + v W0 sinθ r& * = vb cos Θ 3 ( ) ( ) W 0

33 33 KitVes project partners Cesi (IT) Fatronik (ES) Haute Ecole ARC (FR) Katholieke Universiteit Leuven (BE) Modelway (IT) Sequoia Automation (IT) SVMtec (GER) Teks (FR) University of Sheffield (UK) University of Wuppertal (GER)

34 34 References M. L. Loyd, Crosswind kite power, Journal of Energy 4-3, pp (1980). M. Canale, L. Fagiano, M. Milanese. Power Kites for Wind Energy Generation, IEEE Control Systems Magazine 27(6), pp , December 2007 M. Canale, L. Fagiano, M. Milanese. KiteGen : a Revolution in Wind Energy Generation, Energy, 34(3), pp , M. Canale, L. Fagiano, M. Milanese. High altitude wind energy generation using controlled power kites. IEEE Transactions on Control Systems Technology, to appear. L. Fagiano, M. Milanese, D. Piga. High-altitude wind power generation for renewable energy cheaper than oil, in Sustainable development: a challenge for European research, Brussels, May 2009 L. Fagiano, Control of Tethered Airfoils for High Altitude Wind Energy Generation, Ph.D. dissertation, Available on-line: A. Ilzhöfer, B. Houska, and M. Diehl, Nonlinear MPC of kites under varying wind conditions for a new class of large-scale wind power generators, International Journal of Robust and Nonlinear Control, vol. 17, pp , 2007 P. Williams, B. Lansdorp, and W. Ockels, Optimal crosswind towing and power generation with tethered kites, Journal of guidance, control, and dynamics,31, pp , 2008.

35 35 Thank you questions? Contacts: