By Dr. Foster Ross, chief technical officer, Kilfrost
Let’s look at the facts: In aviation we transport more than 2.2 billion passengers annually, in around 23,000 aircraft, yet account for just 2 percent of the world’s CO2 emissions. Aircraft entering today’s fleets are 70 percent more fuel efficient than they were 40 years ago, and we also boast much higher occupancy rates than other methods of transport, with figures in excess of 75 percent compared to 40-50 percent for trains and 30 percent for cars.
Add to this the fact that over the last 40 years hydrocarbon emissions from aviation have been reduced by 90 percent and 15 percent of aircraft and engine manufacturers’ turnover is devoted to research, and you could argue that we do enough. “It’s not down to us to do more” I’ve heard from more than one source. And yet it is.
In the future all those involved in the aviation industry will be increasingly affected by both legislation and voluntary agreements which aim to further reduce the detrimental effects of flying on the environment. For the airport operator and the providers of ground handling services, this will mean both reducing the carbon footprint of their operations and also complying with increasingly stringent pollution controls enforced by local authorities.
Achieving these goals, and meeting the European Union’s commitment to cutting its emissions by 8 percent from the 1990 levels by 2012 under the Kyoto protocol, will require a strong working relationship between the operators and suppliers like Kilfrost. And work is being done as we speak. Recently, we’ve seen research carried out into the use of alternative “non-glycol” based deicers that contain glycerol, and sugars such as sorbitol, but these approaches have been problematic and have not yet provided a totally sustainable or practical solution.
Alternative aircraft deicing techniques such as the use of infrared have been explored, and while this has seen some success it does require a hangar operation, produces significant CO2, has a high energy requirement, and struggles to remove snow where the white surface actually reflects the heat energy. In the real world of winter operations, infrared deicing does not remove the need for post treatments with chemical de- and anti-icing fluids, and to date is only used at a small number locations worldwide.
Other techniques being trialed in the U.S. include the use of forced air, which has had been moderately successful at several locations, but because it takes large amounts of energy, is very noisy and also works best on light, powdery snow. It has not been widely adopted outside the U.S. Finally, the use of hydrophobic — or water-repellent — paints has also been considered for some time but has yet to be proven in practice for civil aviation. So what does that leave? Our dedicated R&D team has explored all of these techniques and have come to the firm conclusion that chemical deicing with glycols is still the most efficient and effective method, but the question we faced was how to improve their green credentials.
Our team, while regularly reviewing the ongoing stream of new bio-based chemicals to identify an alternative to the standard industrial grade propylene glycol, came across exciting work being done by DuPont Tate and Lyle to produce a novel bio-glycol. As a consequence we got in touch and requested samples for feasibility studies. Initial tests on their corn-sugar based glycol, Susterra®, showed it had suitable physical and performance properties to be developed into an aircraft deicer.
The development process from our initial investigations to final approvals testing to AMS 1424, which is the SAE Type I specification for ground based deicers, took just over a year. As well as holdover time testing in Canada to confirm holdover performance, the fluid was subjected to wind tunnel testing to ensure aerodynamic performance, and extensive materials compatibility testing with aircraft parts.