Grape skins and de-icing roads

Posted on 03 September 2020.

Researchers at an American university have invented a process to recycle agricultural waste to make an environmentally friendly additive that will reduce the environmental impact of road salt and safeguard water resources.

In winter, applying a melting agent to the road surface - usually sodium chloride, i.e. salt – will melt the film of ice or snow quickly and make roads safer.
However, there are drawbacks. In cold regions where road salt is extensively used, it can also damage the infrastructure and negatively impact the environment.

For example by running off into rivers or seeping into groundwater, contaminating fresh water sources and threatening vegetation and aquatic animals. The process is known as salinization.
At a TED conference, organic physicochemist Tina Arrowood, who argues for a "circular economy of road salts”, tells of her surprise when browsing through the scientific literature on the health of rivers globally she discovered that a large number of American rivers are affected by the problem.
Sur 232 rivières testées, 37% affichent des niveaux de salinité croissants. Les sites les plus concernés se trouvent dans l’est des États-Unis     . Ce phénomène serait en partie dû à l'utilisation de sel pour déglacer les routes.

The innovative solution - an environmentally friendly additive based on agricultural waste - developed by Washington State University researchers could help mitigate the effect.

Improving the efficiency of road salt

The idea is to improve the efficiency of road salt in order to reduce its use, and thereby the associated risks to both the infrastructure and the environment. The research team ferments agricultural waste, such as grape skins, to make a non-toxic chemical solution that can then be incorporated into the brine used on roads.


The magazine Fast Company reports on how this process was developed. Xianming Shi, a professor of civil and environmental engineering, began work on a de-icing additive as part of a project sponsored by the Alaska Department of Transportation.
At the time, the challenge was a different one: find an alternative solution to conventional road salt, which was ineffective due to the exceptionally low temperatures being experienced in the state. The problem was that magnesium chloride (a more powerful road salt than regular salt) and existing additives were too expensive. The Xianming Shi team therefore decided to use agricultural waste!
According to the researchers, this process could be scaled up. All that remains is convincing the cities and road de-icing companies to use it.