“Made snow and ski tourism in general cannot really be described as environmentally friendly. Energy and water requirements are significant. But optimizing existing systems to use fewer resources and reduce environmental impact can be seen as an environmentally friendly approach,” says Professor Hinrich Grothe, head of the Physical Chemistry of aerosol particles at the Vienna University of Technology in Austria.
A common solution to reduce resource usage is to add additives that improve freezing behavior in the range of zero to minus eight degrees Celsius. But these are illegal in some countries, including Austria. This means that artificial snow – like natural snow – consists of pure water.
Professor Grothe is researching methods to optimize the production of artificial snow without additives. In the EarlySnow project, supported by the Austrian Research Promotion Agency (FFG), he studies to what extent small adjustments requiring little intervention have an impact on freezing behavior. Here is an interview with Professor Hinrich Grothe and team member Philipp Baloh:
What is the problem with additives in artificial snow?
Whether currently relevant additives and Snomax® in particular are problematic is more a matter for ecologists and microbiologists and is the subject of contentious debate among these experts. Briefly, the starting bacterium for Snomax® is a plant pathogen called Pseudomonas syringae. This bacterium also occurs naturally and is found in almost all water-based lacquers in varying concentrations. But the germ is essentially killed and inactive in the Snomax® product. The question arises whether inactive components or fragments can influence local ecology and humans as they are introduced on a larger scale. (Lagriffoul et. al, 2010. Bacterial additives for the production of artificial snow: what risks for human health? Sci. Total Environ. 408, 1659-1666). Whatever the nature of an additive – inorganic, organic or biological – fundamental research must be carried out on the possible risks and impacts on humans and nature as they are applied on a large scale.
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The Rotmoosache in Obergurgl is one of the springs used for artificial snowmaking in the Obergurgl ski area. On the left of the image is a snowmaking pond/water reservoir in which water for snowmaking is stored. Here, water and snow samples were taken from the tributaries, the main stream and the storage pond.
What happens when additives are not used in the production of artificial snow?
Conditions just below zero degrees Celsius make it difficult to produce snow. During their short stay in the air, the water droplets lack the active ice-nucleating particles (INPs) to freeze for the duration of the flight. In the worst case, the drops arrive on the ground supercooled (at temperatures below zero Celsius) and instantly freeze into a layer of ice.
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If strong INPs are present, the droplet freezes faster. The frozen droplet releases less moisture and more used water reaches the ground than artificial snow. But even without commercial additives, INPs are present in all applied waters, the only question is how active they are.
Do certain weather conditions create inconveniences?
Artificial snow can be produced without additives, but requires higher energy and water consumption. This is because high humidity and air temperatures close to zero degrees Celsius reduce both snow yield and snow quality.
What solutions do existing snowmaking systems offer?
Although we do research in this area, it must be said that additives only represent a small percentage of the success of snowmaking systems. The most influential factor is the weather. Temperature and humidity should be low, so timing is important. Ski resorts make snow when the weather permits. This is especially true during the first weeks of the season when a continuous snowpack needs to be created as a base. Another solution is to fine-tune physical parameters such as droplet size, shooting distance, and time required for the process. These are aspects optimized among others by the manufacturers of snow guns.
There are also snowmaking systems that can artificially produce snow without additives even under adverse conditions – using supersonic expansion. But it takes more energy.
Two types of artificial snow systems were used in the EarlySnow project: the artificial snow cloud (by Michael Bacher) and the Snowy (by Frank Wille). In the artificial snow cloud, the powder snow is produced in very high quality but in low quantity. The Snowy, on the other hand, can generate snow even above freezing because the freezing low temperatures are created by rapid expansion once outside the ultrasonic nozzle.
Which snowmaking systems did you work with in the Early Snow project?
During our work in the Obergurgl-Hochgurgl ski area, we also discovered that different solutions are needed for different types of snow. Artificial snow from conventional snow guns consists of grainy ice particles that have little in common with natural snow. On the other hand, it is stable and easy to work with in elevation, even if skiers find it less pleasant to ski. Both natural snow and snow created from the artificial snow cloud are airy in nature and provide a softer skiing feel. This makes it very suitable for the upper centimeters of the slope surface. So there is definitely a need for both snowmaking systems.
What is the solution approach in the Early Snow project?
Since even pure water still contains enough natural substances to be considered ice seeds, an attempt was made to collect and identify these substances in the waters of the Obergurgl-Hochgurgl ski area. It has been shown that, depending on the season, very different ice germs are found in running water and retention basins. We investigated whether these different waters could improve the snow yield of traditional snowmaking systems.
Photo: Over a period of approximately one year, a total of 60 such water samples were collected and analyzed. Whenever possible, samples were taken from the same locations using GPS to ensure comparability.
How to make a practical application?
Unfortunately, we cannot yet draw a direct application from this latest research. The number of active ice seeds in water sources is highest in spring/early summer, an unfavorable period for artificial snowmaking. The choice of source had no influence in the studied ski area (Baloh et al 2021, Baloh et al 2019). But from a research perspective, the results are a starting point for a focused investigation into the nature of ice sprouts present at the site, so we look at the basic properties of biological ice sprouts and what makes a sprout effective ice cream (Pummer et al. 2015, Felgitsch et al. 2018, Seifried et al. 2020).
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Baloh, P., Hanlon, R., Anderson, C., Dolan, E., Pacholik, G., Stinglmayr, D., … & Grothe, H. (2021). Seasonal ice nucleation activity of water samples from alpine rivers and lakes in Obergurgl, Austria. Total Environmental Science, 800, 149442.