Solar Impulse: Solvay’s high-flying innovations grounded in daily applications

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Nearly every single one of you has a piece of “Solar Impulse” in your daily life. The energy-efficient and lightweighting solutions that Solvay has provided for the world’s first zero-emissions aircraft can be found in computers, mobile phones, buildings and residences, automobiles, airplanes and more. Not only are these applications making an impact today, but the prospects for what they could deliver tomorrow are huge.

Sun power

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Since 10 years, the photovoltaic (PV) cells on top of Solar Impulse’s wings are protected from harsh conditions during flight by a transparent surface treated film, based on Halar® ECTFE. Today, PV companies worldwide have adopted films for flexible PV panels for industrial roofs that cannot withstand the weight of traditional glass solar panels. 

Halar® ECTFE films are also being applied to the roofs of car parks or for boat applications. Essentially, whenever there is a need for solar power but the panel must be lightweight, Halar® ECTFE is a perfect solution. As Solvay looks to future applications, the Group has started receiving enquiries for bifacial solar cells - PV cells with films on both sides - actively receiving and transforming solar energy into electricity. This is a particularly interesting application for the building and construction market.

High-performing batteries

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Once the sun’s energy is captured, the next challenge is with storing the unused energy. This is where fuel cells and batteries come into play. On Solar Impulse 2 (Si2), the energy harvested from the sun is stored in 633 kg of lithium batteries. For the aircraft, Solvay (Specialty Polymers) developed a new grade of Solef® PVDF, used as electrodes binder, offering optimal adhesion and helping to reduce the weight of the batteries. Beyond Solef® PVDF, the monofluoro-ethylene carbonate solvent called F1EC or FEC, produced by Solvay (Special Chem), brings the electricity density of SI2’s batteries to a peak performance of 260 Wh/Kg.

Solef® PVDF and F1EC or FEC technologies help achieve higher performance, higher autonomy and enables battery efficiency as well as improved safety. It can be found in applications such as laptops, smartphones, tablets and electric vehicles and aims at reaching :
  • newer generations of batteries such as Lithium-air for Solef® PVDF
  • opportunities within the growing market for wearable and flexible electronics for F1EC or FEC

Industrial-strength lubrication

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Solvay’s Fomblin® PFPE lubricants increase the lifespan of Solar Impulse 2’s gears and bearings, thereby reducing maintenance. These same lubricants are used inside the vast majority of the world’s personal computers and are as well used in windmills and other demanding applications.

For example, they have even been used in space applications to lubricate the engines of the robotic spacecraft Pathfinders used on Mars!

Lightweight metal replacement

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Solvay’s composite material is a key contributor to Solar Impulse’s light weight. The wing skins and wing spar structure of the aircraft were formed using the revolutionary out-of-autoclave technique, which permitted Solvay to produce high quality large composite molds and parts at low cure temperatures. 

Additionally, the aircraft’s screw fasteners that attach various components within the wings are lightweight pieces made of KetaSpire® PEEK and PrimoSpire® SRP. And, for Si2, Solvay assembled a pneumatic cylinder made almost entirely from polymer Ixef® PARA – a robust, yet lightweight material. 

With Sinterline® Polyamide 6 powders, Solvay produced two devices for Si2: the Air Data Computer Housing (ADC) flight instrument and the lighting clips that support the lights at the front of the wings, which saved 78 percent of weight compared to aluminum.

The global trend towards COreduction and resource efficiency are driving greater demand for lightweight composite materials. We expect the use of lightweight materials to grow significantly across all industries. The aerospace industry is currently the biggest user, while the automotive industry is massively increasing its lightweighting efforts. Already used in Formula 1 and high-performance luxury cars, composites should find their way into other automotive segments in the near future.

Solvay has been cultivating a spirit of innovation for more than 150 years.  It is our way of asking MORE from chemistry.  The Solar Impulse 2 project is a clear of example of this and we are proud that it showcases our many state-of-the-art materials.