Alternative baneavisingsmidler og -metoder - en litteraturstudie

The purpose of this literature review was to gather available information regarding runway deicing. The goal was to find a deicing method that is neither corrosive nor environmentally harmful. It has been decided that Evenes Airport will be established as a quick reaction alert (QRA) and as the main base for the maritime patrol aircraft (MPA). Information regarding Evenes is therefore also present in the report because there is an urgent need for a deicing solution, as Evenes is supposed to be ready for QRA in January 2022 and for MPA summer 2022.

To keep runways free from snow and ice, there are three main methods in use: chemical, mechanical and thermic methods. Chemical removal of snow and ice involves use of deicing agents. As of today, the most used deicing agents are salts of acetate and formate, which are environmentally friendly but corrosive. Urea is a deicing agent that was widely used in the past; it is not corrosive but not environmentally friendly as it contains nitrogen and has high chemical oxygen demand (COD). Leaching of urea can lead to eutrophication of nearby watercourses. Betaine is a relatively new deicing agent that has environmental impact between that of urea and formate/acetate, and its corrosive properties are close to those of urea. To prevent that environmentally harmful leachate from deicing agents reach the recipient, the leachate can be filtered through filter media that bind or break down the agent. The leachate can also be collected and led to an area that tolerates the elevated COD load, to a municipal wastewater network or a treatment plant.

Good mechanical snow- and ice removal, and optimized use, can minimize the use of runway deicing agents. Sufficient staffing, good training of personnel, sufficient and good equipment as well as decision-making systems (intelligent runways/runway technology) may contribute to this. These means are already present at many airports.

Heating the concrete/tarmac at airports can reduce or eliminate the need for runway deicing agents. Heating can be hydronic or electric. A new method involving electrically conductive concrete seems to be a relatively inexpensive and efficient method to heat the runway, compared to hydronic heating and normal electric heating cables. In electrically conductive concrete, electrically conductive material (carbon fiber or stainless steel fiber) is mixed into the concrete. When voltage is applied to the concrete block, heat develops because of the high resistance in the material.

At Evenes, FFI considers that there are three realistic options for deicing: continued use of formate, switching to betaine, or electrically conductive concrete. Continued use of formate is likely to lead to corrosion of the aircrafts. To minimize the corrosion, it is essential to minimize the use of deicing agents as much as possible, and focus on maintenance and cleaning of the aircraft. If betaine is to be used, measures must be introduced to prevent a large COD load to nearby recipients, for instance collection of the leachate. If an electrically conductive concrete deck was to be installed, the entire deck at the airport must be replaced, but in return, the use of deicing agents could probably be reduced by approximately 90%.