Many drivers always have a bottle in the garage, but KLM was in danger of running out of antifreeze – which would have major consequences for aviation, which is already at a standstill in these snow-white days. Glycol, a commonly used antifreeze in both households and airports, finally had to be collected by KLM from its supplier in Germany, Clariant, on Tuesday morning.
When extreme winter weather reached the Netherlands a few days ago, KLM suddenly became a major consumer of the drug. The airlines at Schiphol are themselves responsible for this de-icing (de-icing of aircraft), also for other companies. All 25 ‘de-icing vehicles’ have been in continuous use since last Friday, the company reports. This is necessary, because the planes cannot take off with a lot of snow or ice on the wings: that layer disrupts the aerodynamic effect, which is crucial for takeoff.
KLM currently uses 85,000 liters of glycol per day, a spokesperson said. On Tuesday morning, the airline received another 100,000 liters of liquid. Does this mean that a shortage is likely to occur again after just over a day? “We continue to replenish stock,” KLM responds.
As long as the winter weather persists and aircraft have to be cleared of ice, it appears that KLM will have to continue gathering supplies. What exactly is this antifreeze, and how does it work?
Simple fabric
Organic molecules don’t get much simpler than those that make up glycol. They consist of a small compound that is molecularly very similar to water and even more like alcohol. Because they are so similar to water, they can mix well with them – with the result that the diluted water can no longer freeze properly. When water freezes, the water molecules that initially moved freely around each other become trapped in a rigid crystal structure. But if there is glycol in between, this is much more difficult: it disrupts the rigid crystal structure.
This phenomenon is not unique to glycol, although glycol does work very well for ‘de-icing’. Adding salt to water to raise its boiling point causes the same phenomenon: when two substances mix together, they often disrupt each other’s boiling or freezing points.
Hundreds of flights were canceled again at Schiphol on Wednesday due to snowfall.
Photo Robin Utrecht/ANP
The market for glycol is large – in 2025 the total turnover would be $50 billion – because it is used both at an industrial level and by ordinary consumers. Moreover, it is not only an antifreeze, but is also used as a coolant, solvent and building material for plastics (polyester). Shell and the large BASF are the most important producers.
In response to NRC Clariant writes that “exceptional winter weather across Europe is putting unprecedented pressure on aviation supply chains.” The company is working “day and night to support customers” and adjusts planning based on the weather forecast and assessment of where antifreeze is “needed most.” Moreover, BASF responds that there is no shortage within the group, i.e. on the production side.
Traditionally, ethylene glycol was widely used as an antifreeze, .
Environmental damage
A bigger problem with the extensive use of glycol in aviation worldwide is that it ends up in the surrounding waters. Glycol breaks down naturally in water, but that process removes oxygen from the water – resulting in oxygen deficiency.
Schiphol also struggles with this. In 2007, hundreds of fish suffocated in surrounding ditches due to low oxygen caused by excessive glycol concentrations. The Rijnland Water Board twice imposed a penalty of 300,000 euros on Schiphol, which was only paid after going to court – up to the Council of State.
Also read
These are the three main reasons for the chaos at Schiphol. ‘This situation is really exceptional’
The situation seems to have improved since then, says a spokesperson for Rijnland. “After the lawsuit, measures were agreed with Schiphol to ensure that as little as possible of these substances end up in surface water.” Schiphol has since carried out the de-icing at locations where the glycol-water mixture can be collected as much as possible.
The Water Board continues to monitor the surrounding ditches – not by measuring the glycol content, but the oxygen content. It is clear that the lack of oxygen is “not such a big problem” anymore, according to the Rhineland spokesperson.
The journalistic principles of NRC