Airborne Wind Energy

Practical use of AWE systems

Roland Schmehl

28 November 2025

CC BY 4.0

Outline

Content
AWE resource potential 1
AWE resource potential 2
Performance parameters
Annual energy production
Technology deployment
Operational safety
Regulations
Life cycle assessment
Scaling AWE systems
Effect of mass when scaling
AWE in the future energy system

Kitepower

Learning objectives

In this lecture, practical aspects of using AWE systems for renewable energy generation are considered.

Investigate the wind resource available to AWE systems
Assess other aspects that are relevant to technology deployment
Position AWE in the future energy system:
- Remote micro grids
- Utility-scale deployments)
Understand the scaling of AWE technologies
Understand the economics of AWE technologies

Content

Wind resource modeling
- AWE resource potential (Bechtle et al. 2019)
- Classification of vertical wind speeds (Schelbergen et al. 2020)
- Definition of powers, wind speeds, etc
- Annual energy production (Schelbergen and Schmehl 2020)
Technology deployment
- Operational safety (Salma et al. 2019)
- Regulations (Salma et al. 2018; Salma and Schmehl 2023)
- Life cycle assessment (Van Hagen et al. 2023; Wilhelm 2018)
- Scaling of AWE from kW to MW
- AWE systems in the great diagram of flight (Noth et al. 2007; Tennekes 2009)
- Performance prediction (or how to model losses)
- Park arrangement (Faggiani and Schmehl 2018; Kruijff and Ruiterkamp 2018)

AWE resource potential 1

Wind needs to be treated as a statistical property, varying in space and time.

Consider available wind power density at a specific location and operational height.

The conversion process is not taken into account.

The analysis is described in Bechtle et al. (2019).

Atmospheric boundary layer

Stull RB. An introduction to boundary layer meteorology, 1988. doi:10.1007/978-94-009-3027-8

Higher altitude wind

Average wind data measured from 1961 to 1980 at de Bilt, The Netherlands

Wind at sea level

Wind speed ~100 m, near sea level conditions

Wind in planetary boundary layer low

Wind speed ~1,500 m, planetary boundary, low

Wind in planetary boundary layer high

Wind speed ~3,500 m, planetary boundary, high

Wind in vorticity layer

Wind speed ~5,000 m, vorticity

Wind in jet stream layer

Wind speed ~10,500 m, jet stream

AWE resource potential 2

Filter and normalize wind speed data.

Reduce dimension of data using a principal component analysis (PCA).

Clustering wind profile shapes (k-means clustering).

Conversion process taken into account by quasi-steady model (QSM).

The analysis is described in Schelbergen et al. (2020).

Performance parameters

Power curve

Power Curve SKN-PN-14, released March 22th 2024

Annual energy production

Use the statistical wind speed data and the performance model.

The analysis is described in Schelbergen and Schmehl (2020).

AWERA toolchain used for AEP prediction at Maasvlakte II.

Technology deployment

What are the societal, environmental, economic, regulatory and operational challenges that need to be addressed for a successful deployment of AWE technology?

What is needed?

Approach

These are way too many aspects so we need to focus in this lecture on a few key aspects.

Operational safety

Max Dereta

Reliability and safety of AWES

The safety analysis is described in Salma et al. (2019).

Regulations

The assessment is described in Salma and Schmehl (2023).

Life cycle assessment

AWE and HAWT park

Van Hagen et al. (2023)

Scaling AWE systems

Kitepower kites in different sizes (2018).

Soft-kites

Kitepower kite with flattened wing area of 100 m² (2018).

Recap: current prototypes

Developer	Prototype name	Electricity generation location	Kite type	Launching & landing concept	Wing span (m)	Wing surface area (m²)	Kite mass (kg)	Min.–max. operation height (m)	Rated power (kW)
Skysails	SKN-PN-14	ground	soft wing	static mast	15.6–22^a	90^b, 180^c	170^d	200-400	200
Kitepower	Falcon	ground	soft wing	winch	13.3^a	47^b, 60^c	73^d	70-400	100
Kitenergy	KE60 Mark II	ground	soft wing	winch	12.5^a	42^b, 50^c		100-400	60
Toyoya	Mothership v11	ground	soft wing	winch	8	8	5.2	300-600	1
CPECC	Airpower	ground	parachute	pilot parachute	40^a	1256^b	1480	500-3000	2400^e
Wind Fisher	MAG1	ground	Magnus rotor	winch	1.7	0.32^f	1.0	0-50	0
EnerKíte	EK30/Enerwing	ground	hybrid wing	HTOL rotating arm	8-14	4-8	22.7	50-300	30
Mozaero^g	AP3	ground	hard wing	HTOL catapult	12	12	475	200-450	150
Kitemill	KM1	ground	hard wing	VTOL quad-plane	7.4	3	54	200-500	20
TwingTec	Twing (T29)	ground	hard wing	VTOL tri-plane	5.5	2	25	up to 300	10
Windswept	Kite Turbine	ground	rotary	pilot kite	6×1^h	6×0.2		10	1
someAWE	MAR3	ground	rotary	pilot kite	4×1ⁱ	4×0.15			0.5
Kitekraft	SN9	onboard	box wing	VTOL tailsitter	2.4	1.08	32	100^j	12
Windlift	C1	onboard	hard wing	VTOL tailsitter	3.8	0.95	11.3	30-100	2

^a projected wing span
^b projected wing surface area
^c flat (laid-out) wing surface area
^d excluding tether, but including suspended kite control unit and bridle line system
^e rated generator power

^f rotor diameter × width
^g formerly Ampyx Power
^h rotor diameter 4.48 m
ⁱ rotor diameter 3.5 m
^j tether length

MegAWES kite

Eijkelhof and Schmehl (2022)

MegAWES kite

Eijkelhof and Schmehl (2022)

Fixed-wing kites

Joshi et al. (2024)

Effect of mass when scaling

Square–cube law

When a physical object maintains the same density and is scaled up, its volume and mass are increased by the cube of the multiplier while its surface area increases only by the square of the same multiplier.

Effect of mass on cut-in wind speed

AWE in the future energy system

References

Bechtle, P., Schelbergen, M., Schmehl, R., Zillmann, U., Watson, S.: Airborne wind energy resource analysis. Renewable Energy. 141, 1103–1116 (2019). https://doi.org/10.1016/j.renene.2019.03.118

Eijkelhof, D., Schmehl, R.: Six-degrees-of-freedom simulation model for future multi-megawatt airborne wind energy systems. Renewable Energy. 196, 137–150 (2022). https://doi.org/10.1016/j.renene.2022.06.094

Faggiani, P., Schmehl, R.: Design and economics of a pumping kite wind park. In: Schmehl, R. (ed.) Airborne wind energy – advances in technology development and research. pp. 391–411. Springer, Singapore (2018)

Joshi, R., Schmehl, R., Kruijff, M.: Power curve modelling and scaling of fixed-wing ground-generation airborne wind energy systems. Wind Energy Science. 9, 2195–2215 (2024). https://doi.org/10.5194/wes-9-2195-2024

Kruijff, M., Ruiterkamp, R.: A roadmap towards airborne wind energy in the utility sector. In: Schmehl, R. (ed.) Airborne wind energy – advances in technology development and research. pp. 643–662. Springer, Singapore (2018)

Noth, A., Siegwart, R., Engel, W.: Autonomous solar UAV for sustainable flights. In: Valavanis, K.P. (ed.) Advances in unmanned aerial vehicles: State of the art and the road to autonomy. pp. 377–405. Springer Netherlands, Dordrecht (2007)

Salma, V., Friedl, F., Schmehl, R.: Improving reliability and safety of airborne wind energy systems. Wind Energy. 23, 340–356 (2019). https://doi.org/10.1002/we.2433

Salma, V., Ruiterkamp, R., Kruijff, M., Paassen, M.M.R. van, Schmehl, R.: Current and expected airspace regulations for airborne wind energy systems. In: Schmehl, R. (ed.) Airborne wind energy – advances in technology development and research. pp. 703–725. Springer, Singapore (2018)

Salma, V., Schmehl, R.: Operation approval for commercial airborne wind energy systems. Energies. 16, 3264 (2023). https://doi.org/10.3390/en16073264

Schelbergen, M., Kalverla, P.C., Schmehl, R., Watson, S.J.: Clustering wind profile shapes to estimate airborne wind energy production. Wind Energy Science. 5, 1097–1120 (2020). https://doi.org/10.5194/wes-5-1097-2020

Schelbergen, M., Schmehl, R.: Validation of the quasi-steady performance model for pumping airborne wind energy systems. Journal of Physics: Conference Series. 1618, 032003 (2020). https://doi.org/10.1088/1742-6596/1618/3/032003

Tennekes, H.: The simple science of flight: From insects to jumbo jets. The MIT Press, Cambridge, MA (2009)

Van Hagen, L., Petrick, K., Wilhelm, S., Schmehl, R.: Life cycle assessment of a multi-megawatt airborne wind energy system. Energies. 16, 1750 (2023). https://doi.org/10.3390/en16041750

Wilhelm, S.: Life cycle assessment of electricity production from airborne wind energy. In: Schmehl, R. (ed.) Airborne wind energy – advances in technology development and research. pp. 727–750. Springer, Singapore (2018)

Questions?

r.schmehl@tudelft.nl

@kite_power

kitepower.tudelft.nl

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