A review of wind standards as they apply to airborne wind turbines

Testing the Altaeros prototype (2013).

Ben Glass

CEO Altaeros Energies Inc.

28 Dane St Somerville, MA 02143

U.S.A.

ben.glass@altaerosenergies.com www.altaerosenergies.com

A Review of Wind Standards as they Apply to Airborne Wind Turbines

Altaeros Energies Inc. In order to secure project financing for airborne wind

tur-bines (AWTs) and ensure robust operation in real world conditions, a standard set of wind conditions should be defined which must be considered in the design of AWTs. These standard wind conditions are described for tra-ditional, tower mounted turbines in international stan-dards such as IEC 61400-1 and DNV GL’s Guideline for the Certification of Wind Turbines. Certification of stan-dard wind turbines is generally a prerequisite for securing project finance for wind farms, and it should be expected that a similar level of certification rigor will be needed in the airborne wind sector. The nature of AWTs combines elements of wind turbines with aircraft and aerospace systems. As such, IEC 61400-1 is a good starting point but does not adequately describe the wind conditions that AWTs should be designed for. In particular, IEC 61400-1 (and IEC 61400-2 for small wind turbines) does not satis-factorily consider a) the impact of altitude on the direc-tion, magnitude and time content of wind disturbances in the medium and high altitude range in which AWTs op-erate, and b) discrete vertical wind events—downdrafts and updrafts—which may pose a significant risk for AWT operation. A more complete and applicable set of wind conditions may be found by considering aviation guide-lines such as MIL-STD-1797A (for use with fixed-wing air-craft supported primarily by aerodynamic force), USDOT

AC 25.341-1 Dynamic Gust Loads, and USDOT AC 25.415-1 Ground Gust Conditions. These guidelines are based on extensive industry and operational experience, and can provide a complete and credible set of wind conditions for the design of AWTs. In particular, these guidelines contain a detailed description of vertical and lateral wind conditions at ground level (critical for AWT landing oper-ations) as well as low- and medium/high-altitudes. This presentation will provide a review of relevant wind tur-bine and aviation standards/guidelines and suggest an initial framework for a set of standard wind conditions for the certification of AWTs.

Altaeros Energies is an early-stage company working to bring the first airborne wind turbine to market. The Altaeros Buoyant Airborne Turbine (BAT) holds the po-tential to deliver cheap renewable energy to rural, is-land, and offshore sites that face high electricity costs. Founded in 2010 by MIT and Harvard alumni with a back-ground in aerospace, energy, and industrial gases, Al-taeros launched its first functional BAT prototype in 2012 and is now working to develop the first commercial scale BAT. Altaeros Energies, located in Somerville, MA, is a founding member of Greentown Labs, the largest clean-tech focused incubator in the United States. Altaeros closed a US$7 Million Series A investment from SoftBank Corporation in November, 2014.