Kiwi company seeks to solve problem of grape waste in winemaking industry

The wine industry could be on the cusp of an environmental breakthrough.

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Grape seeds, stalks and skins have the potential to contaminate soil and waterways. Source: 1 NEWS

After years of struggling with what to do with a waste product which can contaminate soil and waterways, there could finally be a solution.

Grape marc consists of leftover skins, seeds and stalks after the pressing of grapes. It can become a problem if it’s left and the liquid that comes out becomes a pollutant.

Dried grape marc. Source: 1 NEWS

“So if that's not controlled, that can get into the ground or the waterways,” explains Marlborough District Council Solid Waste Manager Alec McNeil.

Marlborough alone produces an estimated 65,000 tonnes of grape marc a year, which poses big challenges around storage. In recent years that has led to a number of prosecutions.

Giesen Wines Chief Winemaker Nikolai St George says “time means everything” for the industry.

“It’s all this large amount of volume, all happening at once when everyone else is busy”.

Some companies have successfully composted on site, but not on a large scale.

Grape marc in pellet form after being dried at the PacRimEnviro plant in Blenheim. Source: 1 NEWS

Mr St George says while there have been some great ideas, “now we’re getting more restrictions as far as where we can dump grape marc, as far as in the vineyards and how much we can apply, those sorts of things are getting harder and harder to do”.

But Giesen has become the first winery to send its product to a pilot plant in Blenheim, where the waste is getting a new start, having been dried and processed into a powder and pellet.

Experienced food dryer Chris Bowhill was issued a challenge by his wife to find a way to repurpose the marc.

“I started off by building my own little dryer and I went around Blenheim and bought up every single grape I could find,” he told 1 NEWS.

It led the PacRimEnviro Director to build a plant and receiving 40 tonnes of wet grape marc with a high moisture content “and we dried that down to 15 per cent”.

“Once the moisture is removed from the grape marc, the leachate essentially stops, it's become stable.

“And in a stable form it can sit there for years until its further processed,” Mr Bowhill says.

There are already a number of trials underway, “with milking goats, cattle and we've got a sheep's stud down in Cheviot that's using it”.

Grape marc being used in tests by Massey University scientists. Source: Massey University

“We're looking at burning it as a coal replacement eventually in our hospital and some of the schools in Marlborough.”

Marlborough District Council has been awarded $127,711 in funding from the 2018 Waste Minimisation Fund to support a study on grape marc.

It involves Massey University scientists who are researching ways to completely get rid of the material, carrying out a full lifecycle analysis.

They’ll be comparing various options and measuring emissions as they go.

Nikolai St George says the more they look into the future uses of grape marc, “the more excited he gets”.

“It's not only going to help out the wine industry. It's going to create a zero-waste for us. We're going to have the advantage of putting it onto our vineyards later on, but also I see some huge advantages within the wider community."