AirborneMax – Scaling as the Key Issue for Airborne Wind

Elelectricity

generation

Flight operation

crosswind

rotational

someAWE

Vertical take-off and

landing (VTOL)

Horizontal take-off and

landing (HTOL)

Multi-drone concepts

Ligther-than-air concepts

~ Flexible wing concepts

Kitemill

Skypull

TwingTec

E-Kite

EnerKíte

Ampyx

KPS

Kiteswarms

Kitepower

Kitenergy

eWind

Solutions

~

~

KiteGen stem

SkySails Power

~

~

Laddermill

Guangdong

HAWP

tether-aligned

Omnidea

Windswept

AWE

system

➡ with fixed GS

➡

➡

crosswind

X-Wind loop track

KiteGen carousel

~

~

➡ with moving GS

➡

crosswind

rotational

Makani

KiteKra�

Windli�

KiteX

Bladetips

Brainwhere

Altaeros

Magenn

Sky WindPower

➡ on flying device

➡

➡

Kitewinder

➡

Proposed classification of AWE systems from http://www.awesco.eu

Wind

Fly-Gen

Ground-Gen

Wind

Retrac

t

Electrical

power

Generator

gearbox

Power

extraction in

crosswind

flight

Power

extraction in

crosswind

flight

Turbine

generator

Kite

Conducting

tether

Tether

Mechanical

power

Kite

Li�

Wing loads

Tether tension

Tether fatigue at winch

Centrifugal

loads

Speed

Weight of

tether and

conductor

Tether drag

AirborneMax, proposed by NREL 56

Jochem Weber Chief Engineer National Renewable Energy

Laboratory (NREL) 15013 Denver West Parkway Golden, Colorado 80401-3305

USA

jochem.weber@nrel.gov www.nrel.gov

AirborneMax – Scaling as the Key Issue for Airborne Wind

Jochem Weber

National Renewable Energy Laboratory NREL is proposing AirborneMax, a project that will

ad-dress a core question in the large-scale competitive com-mercial deployment of airborne wind energy (AWE). With the convergence to lift-driven technologies, the sector has bifurcated into two prevailing technology concept di-rections: Fly-Gen and Ground-Gen, rigid-wing crosswind kite systems. When targeting utility-scale floating off-shore wind farm deployment, a critical and predominant criterion that can define the superior AWE technology concept is the maximal installable capacity in megawatts per unit/device due to the high balance of plant cost. This provides the working hypothesis of AirborneMax. This project will identify and investigate inherent physi-cal phenomena that can cause up-sphysi-caling limits specific to each AWE type and assess these phenomena from their basic science to their engineering implementation. The presentation of the AirborneMax project at AWEC 2019 will highlight the approach to a profound AWE tech-nology question and bring key players to the table, in-cluding technology developers, strategic investors, util-ities, energy companies, original equipment manufactur-ers, academia and research labs to inform, influence, and support the project, and increase its value to the sector and NREL’s sector involvement. From an airborne, i.e., bird’s-eye perspective, AirborneMax may deliver the first phase in an effort to reveal unknown unknowns to known unknowns and assess their impact; identify potential lim-itations or showstoppers and address, resolve, and over-come these from the earliest possible stage; and high-light the most promising research and technology devel-opment trajectories for AWE to successful market entry at

the lowest possible development time, cost, and risk [1]. This project will: 1) define and model design configura-tions of both Fly-Gen and Ground-Gen systems at single-unit device capacities of 7, 15, and 30 MW, 2) simulate power production operations through methods ranging from first-principle science to in-house software KiteFAST to identify, quantify, and assess all capacity-limiting phe-nomena and identify the potentially superior max ca-pacity technology. Relevant physics include tether drag, weight, tension, strength, fatigue, conductivity, multi-functionality, wing flow, - loads, flight path, speed, accel-erations, structural loading, integrity, flow-induced vibra-tion, oscillavibra-tion, system dynamics, generator efficiency, power density, conductor losses, heat transfer, and oth-ers to be identified during the project, 3) conduct techno-economic analysis using levelized cost of energy (LCOE) and technology performance levels (TPL) [1] of the iden-tified maximal installed capacity-limit configurations, 4) address technological achievability, 5) apply structured inventive techniques such as TRIZ to overcome the iden-tified barriers, 6) develop follow-up researcher, devel-opment, and demonstration strategies and high-priority follow-up projects.

References:

[1] Weber J.W.: WEC Technology Readiness and Performance Ma-trix ś finding the best research technology development trajectory. Proc. 4th International Conference of Ocean Energy, Dublin, Ireland (2012)